Add typedef void VoidCallback(); to dart:core

[abarth]

Would it be possible to add the follow declaration to dart:core

typedef void VoidCallback();

I keep needing this typedef and it seems ugly to redeclare it in every package.

Thanks!

/cc @floitschG

[a14n]

The func package already contains some predefined typedef. VoidFunc0 in this case.

[abarth]

I guess I'm a weird duck in that I'm writing code that can't depend on packages.

[krisgiesing]

The func package is marked as 'discontinued', does that affect the decision here?

[lrhn]

I'm guessing the reason the func package is discontinued is that the language has added syntax for expressing function types directly. You can now write void Function() anywhere you would write VoidCallback and get the same result, without any need to import or declare the type.

We don't plan to add function type aliases for simple types like this, we recommend just usig the function type syntax.

[Hixie]

:-(

void Function() does not make it clear that it is intentional that the type used in one place matches the type used in another. Also, it's less readable than VoidCallback.

[lrhn]

I tend to disagree about the readability. Reading void Function() tells me exactly what the function type is, where reading VoidCallback means I have to look up what it actually means - like how many arguments it accepts.

[Hixie]

Mostly it's less readable just because function signature literals are hard to read in general (they have multiple keywords, parentheses, etc) vs a single word. I agree that VoidCallback is less self-documenting (though that's not that much of a problem in practice since we expose our documentation aggressively).