"TypeAlias" Solves A VERY Common Problem In Python

today we're going to be learning what a type Alias is and what the benefits of using it actually are so first of all usually if you want to create a type Alias you can just do it directly by creating a variable that's going to hold that type for example you might have a tuple of type and and string so next time you use this you can say you have a variable of my type and that's going to have to conform to that Tuple so we have to pass in 10 and hello if we want to avoid any warnings from our code editor and as you know by now type hinting is solely for the developer because this will not stop us from passing in the incorrect type we can still say something such as 10 and 10. the code editor might complain but if we print this python couldn't care less about what we pass in and I actually ran the wrong script there so let's rerun that as you can see it's going to Output 10 and 10 regardless of the type that we have defined anyway that's a straightforward way to define a type Alias so why do they have the type Alias type from the typing module well to explain that let's create another example so for this example I'm going to type in strings and this time we're going to explicitly say that this is a type alias and then we can type in list of type string now we can create something called people and that can be a list of strings and here we'll just insert James and Mario so what is different here well at the moment nothing is different here this is exactly the same as writing people of list of string and it still works the exact same way if we pass in some integers the code editor is going to complain that we expected a different type but now comes the moment that we've all been waiting for now that we understand how we can define a type Alias using the type Alias type we can actually do something that's called forward referencing so forward referencing means that we're going to be using a type that does not exist yet and instead of referring to Strings we're going to create a basket and this basket is going to be a basket of fruits and we didn't create fruit anywhere in our program but since we defined this to be of type type Alias we can now pass in a string and insert a list of type fruit and here type Alias prevents this from being considered a string now it's actually considered a type even if fruit does not exist just yet although if we run this before actually creating the fruit it's going to return to us a string as you can see we're getting the string of list of type fruit and we can verify that by passing in the type that will give us a string back but if we actually create this fruit first of all that warning is going to go away and we're going to give this an initializer which just takes a fruit name and the self dot fruit is going to equal the fruit and this should be of type string and second we can now actually use that type directly in our class for example if we create a method called create basket which will create a basket of fruits we can say okay we want to return a basket from this although you might be asking why didn't you just pass in list of fruit directly while you cannot reference your class inside your class it's going to give you this warning that we have an unresolved reference for type fruit there are other workarounds for doing this but we're just covering how we can use type values here as you can see we're referring directly to list of type fruits and that's what we're going to get back and I just called it a basket but you can call it whatever you want and here we're just going to return three times fruits with the self.fruit inserted so we will return a list of fruit objects when we create that basket now down below we can create something called a banana which will be of type fruit and that will equal a fruit with the name of banana and now we can also reference the basket which will be of type basket and if you hover over the basket you'll see that it's a type Alias for list of type fruits which means here we can type in something such as banana dot create basket and that's going to create a basket from our fruits and if we pass in anything that's not a basket for example a list of string and I just use string that but you get the point it's going to give us this warning that it expected a list of fruit but we got a list of string instead so let's go back to creating that basket and next we can actually print the basket at the index of zero and we can refer to whatever we want from that basket for example we can get the fruit back from that basket and when we run this we will get that banana back so as you can see using type Alias is very nice if you want to create a forward reference but that's actually all I wanted to cover in today's video do let me know what you think about this feature in the comment section down below I would love to hear about it but anyways as always thanks for watching and I'll see you in the next video

Channel: Indently

Views: 11,667

Keywords: pyton, pyhton, pythn

Id: f-elvwTlYCI

Length: 5min 15sec (315 seconds)

Published: Mon Aug 07 2023