Ruby Programming

well hello internet and welcome to my Ruby programming tutorial in this one tutorial I'm going to cover pretty much 95% of the Ruby programming language all of the basic syntax and Ruby is basically a dynamic interpreted object-oriented language in which everything is an object and all of those objects can be overwritten Ruby is one of the easiest languages to read and learn and with rails it just might be the best web development option period in the description underneath this video you will find easy links to all the individual pieces of the Ruby programming language that I cover as well as a link to all of the code that is heavily commented and easily transcribed well enough talking let's start writing some code okay on the left side of the screen I have a basic text editor which is called sublime text I'm trying a different color option here so if you guys liked it please tell me in the comments section below and on the right side of the screen I have the terminal or command line if you were on Windows and if you want to install Ruby I'm not going to go through that it's very easy just go to Ruby - lang org and then whatever and installation and here you'll find all the information you need as well as easy installers depending upon what operating system you're using all right so in this first part I'm just going to briefly cover a whole bunch of different things Wow if you want to put a comment in just put a hash symbol and that is a comment and I go over other different comments as well as we continue you want to print something to the screen very easy to do you could say something like enter a value like that and then variables are either going to start with lowercase letters or an underscore normally lowercase letters and of course after the underscore or lowercase letters you're then going to be allowed to use numbers in your variable names let's say I just go and create the normal way of creating variables is to use dashes between or underscores between all the different words in your variable names and if I want to get data from the user I just type in gets and then if I want to convert that from a string to an integer I would just put dot t-- o-- underscore i like then ask them for another value enter another value and then get that one as well using gits once again and it's very important to convert to an integer then another way we can output data is using puts and the difference between print and puts is print will not put a new line after it prints out your string that on the screen while puts will puts a new line and let's say that we wanted to say something like first number we want to convert this back to a string to do so just put two underscore s if you want to concatenate or combine strings you just put the plus sign and I could put something like plus like this and then continue on with second number two underscore s plus equal two and you can see I'm just continuing to add these together you can skip over to the next line and of course you do not need to put a semicolon at the end of every statement and then if I wanted to actually perform some arithmetic inside of here I can do so and then I would just convert that to a string and if we come over here and you can see the name of my file is Ruby or not Ruby and I'm just going to type in Ruby to execute it followed by the RB extension which is the extension for all Ruby files if I execute it you can see enter a value I can type in two and another value three and there you can see the answer pops up on the screen now there are five main rithmetic operators and we of course have addition subtraction multiplication division and modulus which returns the remainder of a division see over here if I enter those in you can see the answers that show up there on the screen now integers or fixed numbers can store extremely large numbers that do not have decimal places and you can pretty much trust an integer can hold well beyond the number that I displayed here on the screen so they are quite large and Ruby uses a different way of storing integers that allows you to basically be able to store numbers that are that large now let's say I come in here and let's create another integer just to show you an example of the accuracy of floats and this is a float let's just say it's one point zero zero zero and then let's store another float inside of here and one thing to remember about floats is there must always be a number before the decimal place whenever you define them and then we could come in here and just go num1 and convert that to a string plus here let's do some subtraction this time no I'm 99 again convert it into a string plus I'm 1 minus num 99 string say if we execute it you can see that it is quite accurate up until it gets to the very very end of this float where it has that nine basically with floats you can trust that 14 digital accuracy is a basic norm so let's come in here and create a big float and there you go and then let's perform a little bit of arithmetic here big float plus remember always put the zero there and you can see that while it will be able to store up to fourteen digits of accuracy if we try to perform a calculation like this that it is not so accurate in performing that calculation so just like every other programming language float arithmetic is a little bit off so you should be aware of that now I said before that every single thing inside of Ruby is an object and let's just prove that if we come in here and type in one dot class which is going to return the class of whatever precedes it we could even put a float inside here dot class and of course we could come in and put a string inside of here dot class and what if we execute that you're going to see that this comes back to fix number float and string will get more examples of exactly what a object is inside of Ruby basically everything now a constants going to start with an uppercase letter so we can put something like a constant like that and 3.14 however you have to be aware that while we will say this is a constant that doesn't mean we can't come in and also change the value what's going to happen though whenever we run this and we try to change the value for the constant we're going to get an error but it still will allow us to change it anyway as you can see right there there is your warning da-da-da-da-da however the constant value did indeed change and then just to show you one more advanced thing let's say that we want to return a file object it's quite easy to do go write handler and we would use the file object I'll do a more advanced tutorial on this later on at the end of this tutorial but let's say we have a file called your sum we want to write two and we'll just give this the out extension and then say that we want to write to it that's going to create the file by the way if it doesn't already exist we could then very easily come in and put some text into that file let's say we wanted to put random text and you could put variables you can put pretty much anything you want inside of there but you do need to convert it into a string we would then in here and close the file after we are done with it and then if we wanted to read data from the file data from file its equal to we would just use the file object again and say read and then say what you wanted to read from say it's called your some thought out and then put the data on the screen we could do that just that easily and as you can see data from file is random text just that easily we're creating a file wrote to it closed it reopened it read from it now putted the data on the screen and then finally if you wanted to also come in here and load an execute code another Ruby file let's say we have one called Ruby or not Ruby dot RB and let's say give that to as a value we could then come over here and create Ruby or not Ruby - and just say hello from Ruby or not Ruby - save that and then jump back over here and there that is file save and execute and you can see that that is how easy it is to execute code from other different files now let's get into performing some conditional operations another thing to remember though first off is if you want to have a multi-line comment all you would do is equal begin multi-line comments and then equals end that is a weird way of doing a multi-line comment but that is how they are created in Ruby now let's get into conditional operations let's say we have a variable called age and let's give it the value of 12 we could come in here now and use if statements to compare values so we could say something like if age is greater than or equal to five we can also use logical operators like and or or not and then we go age is less than or equal to six we could then come in here don't need the curly braces you might be used to say something like you're in kindergarten like that we could then come in and go else if age is greater than or equal to seven and age is less than or equal to thirteen and I'll put some different data you are in middle school something else that's important is we're going to be able to put multiples different statements in here so we could say yay and then we could say something like else puts stay home it's very important to end your if statement we the term end or the key word end if we execute that you're in middle school yeah shows up here on our screen now it's very important to know there are a couple different comparison operators so the kids Paras and operators are going to be equal to not equal to less than greater than less than or equal to as well as greater than or equal to and then your logical operators which you're going to be able to use to combine and differentiate those different comparisons is going to include and or and not and you could also type and or or not inside of there if you decided that would be something you'd rather do and just to give you a demonstration of those let's say we have true and false is equal to plus true and false to string and let's do the same thing for your other logical operators so here is or and or and then not let's just say not like that and not like that which is going to return the opposite and there you can see exactly how those logical operators are work another comparison operator you have available to you say we'd go puts and we wanted to do a comparison it's going to provide different answers depending upon how the logic works out for that comparison we have this little guy right here and basically what it's going to do is it's going to return 0 if both of those values are equal 1 if the first is greater and negative 1 if the first is less than the other one if we want to perform this operation just to see how this works out then to string and there you can see it shot back negative 1 and the reason why is the first is less than the other one just going to give you a rundown of all the different ways to compare just for completion reasons unless is another comparison operator and it just shows unless age is greater than 4 puts you could say no school else let's go to school and then once again you would put end and you can see go to school comes up here and the reason why is this is only going to execute this line right here if age is less than 4 so that's how in less works there's a bunch of different ways to do comparisons inside of Ruby you're also going to be able to come in here and add conditions to the output so we could say you are young is going to execute if age is less than 30 and you can see that it did another way of comparing things is using the case statement so we can say something like print enter greeting go and get that greeting from the user equal to gets and then we could put Chomp on the end of here if we wanted to remove the newline that goes with the input because the person types the input and it hits newline or enter and that's what Chomp does gets rid of that newline we could then create a case statement that says greeting and then say when what they type in is equal to French we could also come in here and put multiple different stipulations so they can use lowercase or uppercase well then we're going to say Bonjour once again when they type in Spanish or lowercase Spanish you could say hola like that and make sure that is exit and not end exit there you go and then finally we could type in else and this would substitute as the default and we'll just put English inside of here and then we could put puts hello and then the end is actually the ending for the case execute and we could just say nothing and it's going to say hello and we could have come in here and say Spanish it's going to go jolla and we could also come in here and get the English and remove that all together and you're going to get exactly the same results Spanish there you go another conditional we can use is what is called the ternary operator and basically it is going to provide different input depending upon and conditions so we could say if the age is greater than or equal to 50 for example and then we put a question mark it is going to return old as the output or the assignment if the condition is true otherwise it's going to return young if the condition is false and there you can see young shows up let's get into looping this first loop we're going to demonstrate we're going to create a variable give it a value of 1 and then we're just going to type in loop do we could then come in here and go x+ or equal to one which is going to be the shortcut for X is equal to X plus one same exact thing both of these guys right here and you can also put comments right there in the same statement of course and let's say that we wanted to come in here and only print out on the screen even numbers we could then type in next unless X modulus 2 is equal to 0 and next what it's going to do is jump back here to the top of the loop and continue iterating through the loop otherwise if we do have an even number let's print that out on the screen and then let's also use break which is going to throw us completely out of the loop if X is greater than or equal to 10 and that's going to stop our looping and with the loop you're going to also type in end you're going to do that a lot of times if we execute that you're going to see it prints out 2 4 6 8 and 10 so next if it gets down here it's going to add a value of 1 to this which is going to be 2 and in that situation since 2 is an even number it's going to print it out on the screen and then it's going to continue it's going to check is it greater than or equal to 10 no it's going to jump back to the top of the loop it's again going to add 1 this time we're going to have 3 it's going to say does this equal 0 well the modulus of 3 + 2 is going to kick back 1 so it's going to say that that indeed is true so it's going to execute next which is going to jump back up to the loop again it's going to add 1 to it and you're going to get a 4 and continue onward and onwards and then break of course like I said before whenever this condition is met and comes back with a true it's going to continue execution after the loop and end the loop all together let's go in here and create ourselves another variable to show you exactly how it while loops work inside of Ruby let's give this value of 1 we could then come in and go while Y is less than or equal to 10 and then we could increment the value of Y by 1 we could then do exactly the same thing we'll say next unless Y modulus 2 is equal to 0 print out on our screen again the value of y if it's an even number and we could also put break inside of here and say if Y is greater than or equal to 10 we can kick ourselves out but the wild loops going to kick us out anyway because that's already there so we can get rid of this all together and of course we're going to while loop with end as well if we execute that you're going to see 2 4 6 8 and 10 print I on the screen again told you there was a bunch of different ways to loop and use conditionals inside of here let's come up and let's create another variable and this time we're going to cover the until loop which is just a different way of doing things basically it's going to do stuff until a condition is met versus end when a condition is met like the while loop works and to use it you just go until a is greater than or equal to 10 and then we're going to increment the value of a is equal to 1 and we're going to come in here then we could also put next inside of here if we'd like so that we can print our awed and even numbers to is equal to 0 and then in that situation we could print out on the screen the value and again until ends whenever end is typed in or reached in execution there you can see is another way to print out even numbers between 2 and 10 it's actually a couple different ways to use for loops all these are sort of considered for loops we could create here and array and I'll get more into arrays later on it's just basically a box that contains a bunch of different values in memory so there's numbers we can come in and go for number in numbers and in this situation it's going to be cycling through this numbers array and each one of them as we cycle through is temporarily going to be stored in a variable called number look at that now put them by going puts and if you want to have the value of a variable show up inside of a string you put the hash symbol right like that and we go number like this we could also throw a comm inside of there in a space if we'd like and this also ends with end and there you can see it cycles through all those and puts commas there on the screen we could also come in here and go print like this and that time you can see that there is no newline we could also come in here and define an array called groceries just to show that you can cycle through pretty much anything let's say we have bananas sweet potatoes pasta and tomatoes there you go that's our groceries array we could cycle through all of these by going groceries each do you put or food food in this situation is going to be the temporary holding cell for each item inside of our groceries array has its cycles through these there you go puts get some and then if we want to and put the value for food inside of there there we go and of course end this with end as well a whole bunch of different ways that iterating get some bananas sweet potatoes pasta and tomatoes I don't prints out we could also cycle through numbers and this is very simple let's just say we want to cycle through the number 0 through 5 this is called a range which we'll cover more later on and then we can go each do again or is going to be the temporary value as we're cycling through then we go puts hash symbol and then we could put I inside of here and let's put another hash symbol here but this is going to actually be a hash and there that is and again that's going to end with and execute and there you can see all those printed out so there's pretty much every way we can both use conditionals as well as looping now let's take a look at functions now functions are going to start off with de F and then you're going to have your function name so it's a add nums then you're going to have parameters if any inside of here so we'll say num1 and num2 and then you can either return a value or not return a value so I'm going to say num1 and i'm going to convert this into an integer and then num2 and convert that into an integer and then it's going to return that value and functions also end with end we could then come in and go puts add nums and pass three and four into there and execute that you can see seven shows up on the screen now it's very important to understand when you're dealing with functions the variables are passed by value so their value can't be changed inside of a function so that's true even if you have the same name so let's have X is equal to one and then we'll create a function and change that and we will pass supposedly X inside of it then we'll go and give X the value of four inside of the function we will then call change X and we will pass X but this is this X here we're passing doesn't have anything to do with that and you're going to see here if we go puts X is equal to dot and then we'll put the hash some one side of here and X and execute it it's going to print out one so any value that changes inside of a function is not going to affect an outside value and this is very important to remember whenever you're working with functions I'll get more in functions later on but that's the basic gist of how they work so now let's take a look at exceptions now exceptions inside of Ruby a go by different names we're going to be able to catch exceptions in Ruby using both begin and rescue so we're going to say print enter a number and once again we're going to get that value and store it in a variable called first num and we'll use gifts and then convert it from a string into an integer and we'll then say that we want to enter another number and we'll store this in a variable called second num and we'll use gets again now if we think we might have an error we're going to put again and then we're going to put some code inside of here that might throw an error so we're going to say answer is equal to first num / 2nd num then after that we're going to type in rescue which is going to be called if there's an error and here we're expecting the error to be a division by zero so we're going to say you can't divide by zero and then we'll put an end which is actually going to end the begin and also we could come in here and throw exit now if we would come in and go puts first num / 2nd num is equal to and put answer inside of here and make sure you put a closing brace right there as well and execute it let's split three inside here and then put zero and you're going to see you can't divide by zero shows up however if we would go and do something logical like 4 + 2 + 3 whatever it doesn't matter you can see that it does indeed work you can also throw your own exceptions with rays so let's just come in here and delete all this and create a function called check age and pass age inside of here and give a value of equal to 12 we could then say raise argument error and we could say enter a positive number is going to show up unless age is greater than 0 we're going to end that function right there and then we're going to also catch this potential error with rescue so we could say B again and then we go check age and let's pass negative one inside of there let's just ignore the age part there and then we'll be able to come in here let's indent that and say that we specifically want to catch an argument error and if it is triggered we're going to print out that is an impossible age and then and that and you can see if it executes that is an impossible age prints out there's a whole bunch of different ways to use exceptions inside of Ruby we've been doing a lot of things with strings here but let's look specifically at some string functions and a whole bunch of other different things basically strings are just a series of characters either between double quotes or single quotes for the most part you're going to use double quotes though so let's just come in here and go puts add them and one thing it's important that I uncover is if we put a hash symbol in here we'll also be able to do things like perform addition inside of here a whole bunch of other different things not just variable names and then we could throw some back slashes inside of here and let's look at the difference between if we would use double quotes versus single quotes here we can tell them put a single quote there and a single quote there execute that and you're going to see here that the new lines indeed do work whenever you use double quotes as well as this interpolation which is right here that's what that's called if you want to know the technical term and whenever you use single quotes those do not work so something that's important to remember and another reason why we barely ever use single quotes with strings a here doc is normally used whenever you want to use a multi-line string and you want to continue using all of the new lines and things so let's just say multi-line string and how this would be created as you'd put these two carrot symbols here GOM and then you could go something like this is a very long string that contains interpolation like and then you put a hash symbol inside of there and say something like four plus five just to do that and then put some new lines inside of here just to prove that the new lines work and then you would end this multi-line string with the eom at the end you could then come in and print that out multi-line string and execute in there it is you can see all of those different lines and how they kept the new lines and everything all in order with that multi-line string let's go and create a couple different strings here we can say first name is equal to Derrick and last name is equal to anise you can combine or concatenate strings by using a plus sign so we could go a full name is equal to and first name plus last name I could go in here and create another one say middle name is equal to just and you could also combine strings with interpolation so we could say full name is equal to hash symbol and first name and middle name and then last name there we are we could also come in here and check if a string contains a string and let's just use puts here and we go full name and then we would say include with a question mark and what you're looking for inside of that string maybe we got a little bit of an error let's just throw new and underscore inside of there there we are there you can see true came back for that function and we could also get the number of characters that are inside of that string there's 18 to all kinds of things let's say that we wanted to count the number of vowels inside of here so just go Vale's and then go full name dot count and everything you put inside of here is going to count where it's going to find all of them so a e I owe you and let's convert that to a string we could also do the same thing to find all the consonants so throw that there consonants and if we're going to find the opposite of what we're searching for so anything except what we have listed here we're just going to put in a caret symbol like that we could check that a string starts with another string puts whole name start with and then we could throw in last name we could also come in and get the index inside of here or the character number inside of here for a match so we'll go full name again and index and then what we're searching for specifically worked out to a string and there you can see all those print it out for us there's a ton of different functions inside of here we could also come in and check for equality let's go and just delete this puts so if we want to check a equal to a then we can go a equal to a you can see that comes back is true we could also perform a check to see if something is the exactly the same object so it puts if we want it to use a double quote inside of here we'd have to back slash that double quote like that then we could put a and then let's back clash the double quote that allows it to be contained inside a double quotes and then equal question mark back slash double quote a back slash double quote let's concatenate that and then let's actually do operation so we'll go a and then equal a again and to string and there you can see that they show up is false however if we went in and typed in puts and say first name dot equal and then first name inside of there in that situations going back with a value of true because they are the same exact object we could also uppercase every single thing so just type in uppercase we could lowercase everything and then there's also swap case you can see exactly what those do there you go let's say that we then went into our full name and we just put in a whole bunch of spaces inside of here for no good reason except that we want to show exactly how to eliminate that whitespace so full name again we could then strip off all the left whitespace by going full name equal to full name dot L strip and we would be able to also delete any white space on the right by changing this to our strip or we could delete all the white space altogether by just making that strip and just to do a little bit more completions type of thing why don't we cover formatting strings we could also go puts full name or justification and this is going to give us 20 spaces then full name plus everything else is going to come out to 20 spaces and let's say any additional spaces we have of those 20 we want to put dots inside of there we could do that and that's going to be right justified we'd also be able to do left justified as well as Center and it's easier just to show you exactly what this looks like rather than trying to explain it and there you can say here we have right justified here we have left justified in here we have Center we could all so chop off the last character by just typing in chop and we could also come in and use chomp which we covered previously by default is going to eliminate a newline if it exists and if there is no new lines going to do nothing and if we want to delete the last two characters for example we would actually put whatever specifically one that eliminated and there you can see chop just cut off the last letter right there and chomp cut off both of the letters that we defined right there give ourselves a little bit more room here you could also have it delete specific characters that you'd like deleted so let's just go full name delete and it's going to delete every occurrence of a in that situation and we'd also be able to go and create an array from a string by just going full name and calling split and in this situation we're just going to put two symbols there which basically means it's going to just split every where there is a new character or you can split everywhere there is a space for example and let's just copy this and the difference you're going to see here in a moment here we're going to put a space inside here you could also put a comments out there if you'd like if we execute this is the one with just going to show the each individual part of the string in separate parts of the array get more into arrays here in a second and then here you can see it's split everything based off spaces and up here you can see that it eliminated all the A's that we also covered and just to reiterate this a little bit you're going to be able to perform string conversions if you want to convert a string into an integer you just put two underscore I going to convert it into a float to underscore F and if you wanted to convert it into a symbol which we'll talk about a little bit later to underscore symbol and then finally if you'd like to see the most common backslash is you're going to be able to use there they are okay so if everything is an object inside of a ruby we might as well talk about objects now in object oriented objects using classes and just like everyday objects every object is going to have attributes which we are going to call instance variables as well as capabilities which we are going to call methods now let's say that we have a class called animal inside of it you can put and initialize function and this is going to be called anytime a new animal object is going to be created and this is where you would normally put default values here we're just going to say creating a new animal and and that of course I'm going to show you really easy ways to create setters and getters inside a ruby but for now I'm just going to create a setter and getter let's say it gets passed a new name if you wanted to set an instance variable inside of Ruby you would put the @ symbol and then name don't need to do anything else with it and this is going to assign that value like that and of course we're going to want to put end there as well we could then define a getter and you just put @ name and that's going to automatically return that and put end another way you could come in here and get a value is def name and then just put name inside there like that and another way you could provide a setter is go def name equal to new underscore name and one of the reasons we use getters and setters is to make sure that bad data never gets in so let's say we want to make sure that the name that is passed in is not a numeric number we want to make sure we're using characters here we can just go numeric like that and if it is a numeric we're going to say name can't be a number something like that else we're then going to assign the value that was passed in there to our name instance variable and here we will end the if and here we will end the setter method and then finally we're going to end our class so that's how that all structures out now after we've created this class we'll be able to come in here and create a animal object so let's say we want to create an object called cat we would just call animal and new and that's going to create that animal object we could then go cat set name and pass in a name for it we could then get the name of it cat get name the alternative way of getting name will just be cat and then just typing a name which is normally what you would use like I said I'm going to show you a shortcut for generating getters and setters in a second and in an alternative way of actually setting the name just be this and then let's say we want to type in this new name puts cat name again and there you can see creating a new animal and that's the initialize function it's going to be called every single time new animals created and you can see all the different ways that we are using to set the name and get the name and exactly how they work pretty much exactly the same when I go and create the new and improved dog class and here I'll show you the shortcut for creating all your getter functions you're never going to type this in though because I'm going to show you a way to generate them all named in this situation is a symbol which like I said we'll talk about a little bit later on and let's say you wanted to also have a weight instance variable inside of here those are going to create all of your getter functions automatically if you wanted to create all of your setter functions you just again list all these different instance variables you want to have and there you go or you could create all your getters and setters with one statement by just typing attr accessor which is normally what you're going to do and then type in your instance variables again and wait there you go now we could come in here and define another function called bark which is just going to return a generic bark and close that and then close your class now we could create a dog dog object like that do that up so we can see it all at one place could then go Rover name just to prove that we have our getters and setters just call him Rover output Rover on the screen with Rover name and there you can say Rover prints out on the screen just like we set it now whenever we inherit from another class you get all of the methods as well as instance variables automatically so let's go and create another class and we'll call this German Shepherd and how you inherit from dog in this situation is just putting that carrot symbol in there with dog and of course you would be able to come in here and inherit everything but also overwrite so let's say we went have loud bark print out instead of generic bark here you can do that and it close off your class everything automatically goes through let's say we create a German Shepherd called max German Shepherd there he is again type new and you'll be able to come in here and define name even though you didn't define it inside of the German Shepherd class because it was inherited and when we talk about printf printf is going to be able to do some formatted printing for us so let's say we want our strings inside here strings is going to be a percentage sign and s now we can go goes percentage sign s and then we want to throw a new line inside of there we would then be able to go max name and Max bark and if we execute it you can see everything works out now let's talk about modules modules are made up of methods and instance variables just like classes but they can't be instantiated which means you can't turn them into an object we can use most common reason you're going to use these is the to add functionality to a class because we're only going to be able to inherit one class when we're creating a class but we will be able to inherit multiple modules let's start off by creating a couple modules here we're going to create one called human and how we create a module is just go module and I'm going to call this human remember if we want to automatically have our getters and setters set up for us access err there we go and then let's say we have name height and weight there we go we could then define a function inside of it and if we wanted to output a specific name for our specific object we'd use self just like you use this and many other programming languages and then we could just have the name show up there and runs close that off and just like everything else to close off the module we put an end there and I'm going to call this human RB is the name save it and let's go and create another one this module is going to be called smart then we'll put a function called act smart inside of it and whenever that's called it's going to return e equals mc-squared for example and we'll close that off and we'll close off our module and we're just going to call this smart RB save it I'll jump back over into our regular class we've been using here or regular file now if we want to allow access to those modules we're going to have to go require relative at the top of our file here and then type in what we want and has to be in the same directory of course relative again and we're also going to put smart inside of here we could then create another module just create a whole bunch of modules and this one's going to have a function called make sound and whatever it's called it is just going to print out girl on the screen and that and that this is just a show you can have modules in different places but you normally want them in separate files it's just easier to work with we would then be able to create a dog class inside of here and if we want to include that module we just go include animal and end and you'll see here we can go Rover is equal to create a new dog object like that and then Rover and we could say make sound and there you can see ger prints out on the screen we could also create a class called scientist and we could include our human module inside of here just by going include human we could also include our smart module inside of here and if you want your module to supersede so that if a function is in both this class as well as the module you are taking it from you would use prepend instead of include and we'll go smart here then what we're going to do is we're going to define a function called act smart but remember our function in smart is going to supersede this one even though we created it inside of here because we used prepend instead of include and in this one we'll put a different version MC let's say squared like that just you can see it and then we'll close off our class again now you can see if we create Einstein is equal to scientist dot new and we go and create a name Forum and make that name is equal to Albert like that we can print that out Einstein just like that and we could also go Einstein call the run function inside of the human just to show that that works and then go Einstein name says Einstein dot act smart save that and execute you can see right here equals mc-squared shows up instead of this and the reason why is we use prepend right there and if you look up here you can see the version that actually prints out on the screen that's a way of using modules and classes and objects and all a bunch of other different things something else that no doubt will come up people think about is polymorphism and works a little bit different inside of Ruby let's say we have a class called bird and it has a tweet method tweet what we would do here here is so that you know statically typed languages use something called duck typing to achieve a version of polymorphism and the reason why they do that is languages like Ruby pay less attention to the class type versus the methods that can actually be called from an object so let's say we have bird and tweet just like we said what we would do here is have bird type and we would call tweet on that so the actual object that's being passed in here we would then call it specific version of tweet you're going to see here in a second what that looks like so we'll go end and end this class as well then we're going to create something else another object called Cardinal or another class anyway it's going to inherit from bird and then we're going to put tweet inside of it as well in this situation we're going to go and print tweet out on the screen when that's called and then let's create another one not a class called parrot also going to inherit from the bird class it's also going to have its own version of tweet make sure that's lowercase puts and whenever it's called it's going to squawk there we are now we can create a generic bird which is going to be of bird type and what we'll be able to do to simulate the polymorphism is called tweet and then pass in a cardinal in this situation and new you know you can go and create it create the Cardinal object outside of here of course and then we'll go to eat and then in this situation we'll call parrot no and if we execute that you're going to see the tweet tweet prints out for our Cardinal which we have right here while squawk prints out for the parrot right there so there's an example of duck typing and polymorphism inside of Ruby now I'm just going to briefly cover symbols now symbols inside of Ruby are basically strings that cannot be changed and you're normally going to use them to either conserve memory or to speed string comparison and you would usually use a symbol versus a string whenever you need a string that's value doesn't need to change as well as you need a string in which you do not need access to string methods they're very commonly used in hashes for keys and so forth again we're going to get into hashes in a second symbol basically looks like this and its value is whatever it is right there let's just go and print it out on the screen just so you can sort of see this so let's go puts and dark and then let's bring a couple of these guys in here five those and also let's convert it to a string just to see what it looks like and if we come over here and execute you're going to see Derek Derek symbol which is the class type shows up there as well as a unique object ID and like I said we're going to get more into those as time goes by but you may also remember a symbol here which you use previously in which we automatically generated our getters and setters inside of our function look like that remember type in weight as well symbols are used a lot inside of Ruby and like I said before they're very often used as keys inside of hashes since we mentioned hashes won't we talk about something that's very similar first called an array well we have already seen a raise let's go and create a couple arrays here a couple different ways you can create an array you could call array new like that you could create an it different array by going array dot new and then saying that we want five spaces in our array or five little slots where we can put stuff in that situation the default value is going to be nil which means pretty much not a value and we create an array also by going array new and saying that we want five spaces set aside and the default value in this situation would be empty and we could also go create an array by actually passing values and you can store anything in an array you can store one you can put a string inside of there if you'd like there's three or you could put float inside of there it's not going to bother anything and let's say we want to come in here and print these out on the screen just to see what they look like there you go there's empty empty empty this is actually where we have nil which is not a value and here we have empty and here you can see that we printed out all the different values that we stored in our forth array now with arrays they are going to start off storing things in an index of zero which is very common so if we just typed in two here you can see the three shows up but that's zero one two that's how we're going to get all those different values inside of our array we would also be able to come in and earn to values starting at the second index for example by just putting two and two right there and I'm going to put joint inside of here so we'll join all of our results together and separate them with a comma and a space and there you can see that's how that worked out we could also come and return values by doing values underscore at and then inside of here we could list we want the zero index the one index in the three for example and once again we're going to join those together with a common space and put a dot inside of there because that is a method execute and there you can see it returned those nicely for us we would also be able to come in here and add a value to the beginning of our array by using on shift and then whatever value we want to put in there let's say we want to put zero inside of there we could also go and remove the first item in an array by going shift and then there's not going to be anything because it's just removing an item we could add one hundred and two hundred for example to the end of array by just going push and play around with these on your own to see exactly how they work and that's going to add two values to the end while if we would go in and type in pop that's going to remove one item from the end of our array we could also come in here and concatenate or join two arrays we could create a brand new right here if we'd like so we'd say we wanted to put 10 20 and 30 that's going to add that to the very end of our array and there's a whole bunch of different methods we could use if we wanted to get the size rate for and type in size put our braces there and let's say we want to convert that to a string there you go ray size is equal to eight we could also check that an array contain the value so it contains 100 for example and here instead of size we're going to put include and question mark and then whatever you're searching for 100 for example we could check how many of those matches we have so how many 100s for example and then take the size out of here and instead put count inside of there and specifically what we're looking for and we could also check to see if the array is empty by just going that and then we're going to type in empty question mark 4.2 a string and there you can see all those come back we could worse just like I showed you with join before convert our array into a string puts array for dot join and then however you want those combined into your string P is pretty cool because it's going to allow us to print out the entire array on the screen in just one way which is kind of neat and we could also print out our whole entire array in a loop situation by putting each inside of there and we saw this before at symbol let's say we want each of these individual values in our array to temporarily be stored in a variable called value and then we could go puts and value as it's suiting through there and then end that and if we execute all those things show up right there on our screen so pretty cool so that's pretty much everything you want to know about using arrays while we look at a close cousin to array called hashes and a hash is just a collection of key value pairs so let's go and create ourselves a number hash for example we would use curly braces in this situation and first you're going to have your key instead of indexes you have keys and then you're going to put that little symbol right there and then whatever you want the value to be associated with that and then you can put a comma and then let's go and say we want another one to be called golden put that little symbol there 1.618 and then let's say we want another one to be e little symbol 2.718 and that is how you create a hash inside of Ruby now let's go and use them we could go puts to get the actual value number hash and let's just pass in well make sure you put square brackets here square brackets and whatever the key is and that's going to print that out on the screen for you so we're just using keys instead of indexes which are sometimes easier to use say we want to create a superhero type of hash and of course you could have these all be on separate lines just so they show up easier on your screen and go like that do whatever you want and of course you're going to be able to call superheroes again and pass in Clark Kent for example make sure you have the key exactly the same though and there that shows up a Superman you'll be able to come in and add an individual new key and value to your hash by just going superheroes and then defining whatever you want the key to be right like that automatically going in and adding in a new value for that key there it is it's in there now something else is you could add a default key value which is very useful so that if the user goes and looks for something that doesn't exist inside of your hash it's going to print out something useful like no such key if it can't find anything which is like I said pretty useful so you go in here and say I want to get whatever is in sample hash with the key dog it doesn't exist and you see no such key comes up we could then come in and create some super heroines hashes right like this you could then combine these with update by just putting in super heroines instead and whenever you're using update this is considered a destructive merge which means if there's any duplicates they're going to be eliminated you could instead use merge which would be a non destructive which would keep all the keys and values even if they matched normally you're going to use update because you wouldn't want any duplication inside your hash I'll just cost confusion now if you want to go through exactly how to print all of these out we would just go superheroes and we would use each again do you could get the keys and values by just putting in key and value and then close that and then we'll go puts and then we go key and we need to convert that to a string plus put some separation between these and a value and end execute you can see all of them print it out real nice and of course there's a whole bunch of different functions available for hashes as well we could come in here and check that our superheroes hash has the key of Lisa Morel like this also be able to come in and check if we have a value by passing in a value so there's Batman and you can see right there's Batman this is the key that's the value and of course we could check if it's empty as well as whatever the size is for it if we execute that you can see all those come out there and the only other thing I could think of is how would you delete a key you would go in here and go superheroes and delete and you could pass in whatever would be a matching key and that's going to delete that for you if we wanted to double check that that actually was deleted in here see if the actual value for the size changed and yes you can say five and four so those are all the main things you'd ever want to know about using hashes inside of Ruby so why don't we go and check out enumerables now a class that includes the enumerable module is going to gain collection capabilities sort of like we saw with arrays and hashes now let's just come in here and create one let's call it menu and let's say include enumerable just like this one requirement however is if you're going to inherit this you're going to have to provide a function that is called each now we're going to put inside of here all the different things that we're going to have in this enumerable so if we have a menu we're going to have pizza and you're going to find all these different options by putting yield inside of here for each of the possible options and salad and water and bread is keeping it simple courses is going to end with end and then the class will end with end will then be able to go and you options and create a new menu just by using new just like we're used to we can in cycle through all those by going menu options and guess what each do again just like we've seen many times temporarily held in item and we could put puts and we could have an automated sort of waitress here would you like and then put in an item and put end there we go and ask would you like all the different things on our menu we could then check to see if we have a pizza for example so menu options go find then inside of here well make sure you use curly brackets in a situation it would say item and we would check if any of these items is equal to pizza and if it does find a match it's going to print that out we do all kinds of weird things let's say that we wanted return items that are 5 letters in length we could come in here and say select and this is going to cycle through all these different options so we could say so item item size less than or equal to 5 likewise we could use reject instead of select reject and it's going to reject anything that meets those options we could also come in and print out the first item we have we could also come in and print out the first two by using take like this we could return everything except for the first two by using drop it's not going to affect the enumerable in any way just going to show those and onwards and onwards we could also menu options get the minimum item we could also get the maximum item and that's going to pend upon alphabet order or whether you have numbers or letters or whatever we're also going to have sorting options and we could even return every single option in reverse order if we'd like so go reverse each just to be kind of silly here there we go execute and you can see everything prints out there on the screen so there is pretty much everything you want to know about enumerables and we're pretty much done I figure why don't we just cover the file object because it's very useful as you saw before if you want to create a new file that you want to write to use the file object followed by new and then you would provide a name that you would like to have assigned to this new file you create I want to be able to write to it just put a W inside of there and there you go you have a file you can write to if it's not created it will be created then you can just use puts to automatically go in and throw some information into your newly created file let's just throw in three authors after you open it and put things in the file you would of course want to close it you want it to output everything that is an assigned to this file object you would just use read and then pass in the file that you wanted to pull information out from just check to make sure all that works and yes indeed it does if you want to open a file for appending just use the file object again followed by new and authors out and then in this situation instead of a double if you want to append to the end of the file you would put an A inside of there then come in and throw in a new author that you may have forgotten Danielle Steel for example and of course close that file again then if you wanted to read from this file again just to make sure that it updated you can see that Danielle Steel is now there this didn't copy this multiple different times just shows that way because we have this other read here then let's go and create another file equal to file well make sure that's uppercase no and let's call this one off there's info out and it's a new file that hasn't been created let's make it writable and in this situation we're going to put a whole bunch of information in here so we're going to have the author's name their language the type of poetry or types of books they wrote and the number of items sold on our screen close our file and then let's say we want to cycle through the data to write out sentences based off the data that's stored inside of there well you go file open and then we could type in author info like this out there is the name of our file do we're gonna be able to use do again and we could say each one of those lines is going to be a record and then we could go record each do we could have each line of that document go inside of the item here we could then split each line into four parts based off of commas so we'll say name will be the first one lying will be the next one specialty will be the next one and sales will be the next one is equal to item this item represents the whole entire line and we can say chomp which means all that information is going to be split based off of commas and then after we split all that stuff we could go put and make some neat things let's say name was a and we could say what type of book make sure you have the curly brace clothes there was a and we type in language author that specialized in and whatever their specialty was and then say something like they sold over and whatever the sales were for their books and then books and then after that we want to close this off and then close this off and if we save that and jump over here you're gonna see when Shakespeare was an English author specialized in plays and poetry they sold over 4 billion books so there you go guys there is a heck of a lot of information about Ruby please leave your questions and comments below otherwise till next time

Channel: Derek Banas

Views: 627,676

Rating: 4.8993478 out of 5

Keywords: Ruby Programming, Ruby (Programming Language), Ruby Tutorial, Ruby Programming Tutorial, Programming Language (Software Genre)

Id: Dji9ALCgfpM

Length: 55min 29sec (3329 seconds)

Published: Mon Feb 23 2015

Reddit Comments

[u/trowawayatwork]

why are people downvoting? is it not a good tutorial?