Added static_face as variation of face

[bleuthoot-sven]

This copies the face() function in user.rs, but uses static_avatar_url instead of avatar_url.

I am not sure if the #[must_use] is needed, since I don't exactly know what it does. If not, I will remove it in a follow up commit.

[bleuthoot-sven]

Something of note, the model/guild/members.rs does not have a static_avatar_url function, so I did not add the static_face function to there.

[arqunis]

I am not sure if the #[must_use] is needed, since I don't exactly know what it does. If not, I will remove it in a follow up commit.

#[must_use] is an attribute you can use on functions and structs. If on functions, it will prompt the compiler to issue a diagnostic if the caller of the function forgets to use the return value in any way, e. g.:

#[must_use]
fn rand() -> i32 {
    4
}

fn main() {
    rand(); // warning: unused return value of `rand` that must be used
}

On structs, the effect of the attribute will apply anywhere the type is used (that is, in any function where it is used as return type).

It is very useful if the whole point of calling a function is to perform further calculations on its return value, as the function does not have a side-effect (like writing to the filesystem); or if it does, there could be reasons why ignoring the return value might be bad (for instance, Results, because they might be Errs, or Iterators and Futures, which perform no work until next()/poll() is called).

[bleuthoot-sven]

I am not sure if the #[must_use] is needed, since I don't exactly know what it does. If not, I will remove it in a follow up commit.

#[must_use] is an attribute you can use on functions and structs. If on functions, it will prompt the compiler to issue a diagnostic if the caller of the function forgets to use the return value in any way, e. g.:

#[must_use]
fn rand() -> i32 {
    4
}

fn main() {
    rand(); // warning: unused return value of `rand` that must be used
}

On structs, the effect of the attribute will apply anywhere the type is used (that is, in any function where it is used as return type).

It is very useful if the whole point of calling a function is to perform further calculations on its return value, as the function does not have a side-effect (like writing to the filesystem); or if it does, there could be reasons why ignoring the return value might be bad (for instance, Results, because they might be Errs, or Iterators and Futures, which perform no work until next()/poll() is called).

Ah, that's quite useful to know. Thanks for the information.