What are arguments in a function Python

Generally when people say parameter/argument they mean the same thing, but the main difference between them is that the parameter is what is declared in the function, while an argument is what is passed through when calling the function.

Here, the parameters are a and b, and the arguments being passed through are 5 and 4.

Since Python is a dynamically typed language, we do not need to declare the types of the parameters when declaring a function (unlike in other languages such as C). Thus, we can not control what exact type is passed through as an argument to the function. For example, in the above function, we could do add("hello", "hi").

This is where functions such as isinstance() are helpful because they can determine the type of an object. For example, if you do isinstance("hello", int), it will return False since "hello" is a string.

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00:00 Now that you’ve learned what *args and **kwargs are for, you’re ready to start writing functions that take a varying number of input arguments.

00:07 But what if you want to create a function that takes a changeable number of both positional and named arguments? In this case, you have to bear in mind that order counts. Just as non-default arguments have to precede default arguments, so *args must come before **kwargs.

00:22 So the correct order for your parameters is this: standard arguments come first,

00:29 followed by *args arguments, and then finally **kwargs arguments. So for example, this function definition is correct. The *args variable is appropriately listed before **kwargs.

00:41 But what if you try to modify the order of the arguments? For example, have a look at this function. Now, **kwargs comes before *args in the function definition.

00:50 If you try to run this example, you’ll receive an error from the interpreter. In this case, since *args comes after **kwargs, the Python interpreter throws a SyntaxError.

*args is the short form for Arbitrary Arguments 

If the number of arguments to be passed into the function is unknown, add a (*) before the argument name.

Lets say you want to create a function that will sum up a list of numbers. The most intuitive way will be to create that list and pass it into a function, as shown below. 

However, if we do it this way it means that we will have to create a new list every single time. 

So an alternative will be to use*args where you can pass a varying number of positional arguments instead of creating a list to store these arguments.

Lets edit our sum_function()

*args is just a name. We can change arg to anything we want like how we changed it to *numbers above.

The important thing here is the unpacking operator (*). 

The operator will take all positional arguments given in the input and pack them all into a single iterable object. Take note, the iterable object will be a tuple not a list.

Tuples and lists are similar in all aspects except that tuples are not mutable. Immutable means its values cannot be edited after assignment.

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