Add a TODO function that can be assigned to all types.

[rensPols]

It would be great to be able to pass a todo() function as an argument to make the compiler happy while you're testing/working on something else.
Kotlin already has such a function.

I've created my own function that does this, but since it is not native, it is not integrated with any IDE features concerning the TODO's in code.

// Optional reason
/// This function can be placed on a variable or parameter whose value is yet to be implemented.
Never TODO({String? reason}) {
  throw UnimplementedError(
    reason ?? 'TODO: Implementation missing (an empty todo() has been called)',
  );
}

// Mandatory reason
/// This function can be placed on a variable or parameter whose value is yet to be implemented.
Never TODO(String reason) {
  throw UnimplementedError(
    reason,
  );
}

I don't have a strong opinion on whether the reason should be optional or mandatory, but I would prefer the mandatory variant.

Usage

if (snapshot.hasError) {
  return Center(
    child: TODO("Display the error")
  );
}

var data = getData(
  "[type]",
  TODO("get the data range that has to be collected"),
  [
    Filter([..]),
    Filter([..]),
  ]
);

I hope this can be implemented!

[rrousselGit]

since it is not native, it is not integrated with any IDE features concerning the TODO's in code.

There are IDE extensions floating around to make custom TODO patterns.

You could flag TODO(.+?) as a a todo, and that'd work

[mmcdon20]

Dart has support for TODO comments with IDE integration.

[rrousselGit]

I'm pretty sure they know about that already.
This is about reducing the boilerplate for both // TODO + throw Unimplemented

[FMorschel]

We could also add optional parameters like person or something to better represent Flutter style TODOs. I like this idea.

[rensPols]

@rrousselGit Thank you for pointing out the IDE extensions; I'll look into them. However, I would still very much prefer this function to be in the standard Dart SDK, because now I have to ensure that every developer in the project is using it. Also, another problem that occurs now is that if this function is used, currently, the Dart compiler/linter marks everything after that as unreachable, which it is, but it shouldn't be marked like that if it is a TODO.

To continue on @FMorschel, I think it would be a good idea indeed to add everything in the flutter_style_todos in the future. This would include:

• message
• username
• issue URL

But even without the username and issue URL, having this function in Dart would still be incredibly pleasant. I think we should first focus on having that inside Dart before we talk about adding Flutter-specific functionality.

Because if we take the flutter_style_todos into account, the function signature needs to change depending on whether the flutter_style_todos linter is on or not. This would delay having this function a lot.

[FMorschel]

Because if we take the flutter_style_todos into account, the function signature needs to change depending on whether the flutter_style_todos linter is on or not. This would delay having this function a lot.

I'd like to disagree here. We can make this lint trigger here if the TODO invocation doesn't have all of the required parameters.

[lrhn]

It's not so much a function that can be assigned to any type, but one whose return type can be used in any context.

Even if the version of a TODO function above was in dart:core, it would still make everything after its call unreachable, that's just what Never means.
It might be possible to suppress the warning message, but the flow control has to treat it as returning Never.

Another option would be:

@Deprecated("Implement this")
// ignore: non_constant_identifier_names
R TODO<R>([String? message = "TODO"]) {
  throw UnimplementedError(message);
}

This function should adapt its return type to the context's expectation, and the Deprecated annotation will give you a warning everywhere you use it. That alone should give the behavior that is being asked for.
(If we had another annotation which meant "Don't have this in production code"

I don't know if this is a pattern that we'll want to endorse to the point where we add it to the platform libraries. It's sort-of nice, but I'd probably just write throw UnimplementedError("message") directly.

(Or use @doNotSubmit from package:meta instead of @Deprecated(...), it should still ensure that a real implementation is added before the code is considered complete.)

The case of "TODO" is obviously not lower-camel-case. Since it's intended to stand out, that could be argued to be working as intended. It could also be todo, but then it loses the visual link to the comment syntax.

[lrhn]

We could also add optional parameters like person or something to better represent Flutter style TODO

Sounds like a function that Flutter should be adding to their platform libraries, not one belonging on the Dart SDK, which does not have any recommendations for todos.

If the Flutter recommendations for TODOs change, they would be in a position to update the function.

On the other hand, if Flutter wants a different TODO function than the plain Dart SDK, maybe the function is not really generally applicable. That's an argument against adding a function to the Dart platform libraries.
The Flutter SDK could modify the function, giving it more parameters than the Dart SDK's version, but then code using it couldn't be run on both. Or Flutter could have another TODO function in their own package, say package:flutter/widgets.dart or something else which is commonly imported. That would take precedence over one in dart:core in name resolution, but you can still use a TODO from dart:core if you really want to.