Visibility and Privacy

These two terms are often used interchangeably, and what they are attempting to convey is the answer to the question "Can this item be used at this location?"

Fe knows two different types of visibility for functions and state variables: public and private. Visibility of private is the default and is used if no other visibility is specified.

Public: External functions are part of the contract interface, which means they can be called from other contracts and via transactions.

Private: Those functions and state variables can only be accessed internally from within the same contract. This is the default visibility.

For example, this is a function that can be called externally from a transaction:

pub fn answer_to_life_the_universe_and_everything() -> u256:
    return 42

Top-level definitions in a Fe source file can also be specified as pub if the file exists within the context of an Ingot. Declaring a definition as pub enables other modules within an Ingot to use the definition.

For example, given an Ingot with the following structure:

example_ingot
└── src
    ├── ding
    │   └── dong.fe
    └── main.fe

With ding/dong.fe having the following contents:

pub struct Dyng:
  my_address: address
  my_u256: u256
  my_i8: i8

Then main.fe can use the Dyng struct since it is pub-qualified:

use ding::{dong::Dyng}

contract Foo:
 pub fn get_my_dyng() -> Dyng:
        return Dyng(
            my_address=address(8),
            my_u256=42,
            my_i8=-1
        )