external_internal_functions.md

Chapter 8: External / Internal Functions

As we discussed in the previous chapter, all functions must include one visibility decorator (@external or @internal).

Decorator	Description
@external	Function can only be called externally
@internal	Function can only be called within current contract

We would want to create some functions which should not be called externally. For such functions we would use the @internal visibility decorator.

Let's look at how to declare an internal function:

peopleToAge: HashMap[String[64], uint256]

@internal
def _addPerson(_name: String[64], _age: uint256):
    self.peopleToAge[_name] = [_age]

This means only other functions within our contract will be able to call the _addPerson function and add to the peopleToAge mapping.

Notice the underscore (_) at the start of the function name and the parameters. It is a naming convention to add a underscore (_) in front of an internal function name and its parameter(s).

Put it to the test

Our contract's createPokemon function is currently external — this means anyone could call it and create a new Pokemon in our contract! Let's make it internal.

1. Modify createPokemon so it's an internal function. Don't forget the naming convention!

** Template **

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** Solution **

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** Previous Chapter Solution **

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