Mirrors and runtime information for current function

[DartBot]

This issue was originally filed by off...@mikemitterer.at

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What steps will reproduce the problem?
class RestSimulator {

@path("/var")
void functionOne() {
  final Type type = this.runtimeType;
  final InstanceMirror instanceMirror = reflect(this);
  final ClassMirror classMirror = instanceMirror.type;

  final MethodMirror methodMirror = ?????
  var metadata = methodMirror.metadata;
  var path = metadata.first.reflectee;

  print(path.toString()):
  }
}

What is the expected output? What do you see instead?
I want a MethodMirror for "functionOne" but without doing something like:
final MethodMirror methodMirror = xxx.functions[const Symbol('functionOne')];

The MethodName (Symbol) of the current function should be available at runtime.

What version of the product are you using? On what operating system?
Dart Editor version 0.6.5_r25017
Dart SDK version 0.6.5.0_r25017

Please provide any additional information below.

[DartBot]

This comment was originally written by off...@mikemitterer.at

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If someone is able to correct the typo in the headline... pls change it.

[DartBot]

This comment was originally written by @mezoni

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This is a compile-time constant but not the runtime.
Currently Dart language does not support the compile-time constants.
You cannot get function name without having reference to it.
Also in Dart not possible get these common compile-time constant:

• Class name
• File name
• Line number

[iposva-google]

I am assuming this is in the context of dart2js, correct?

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Added Area-Dart2JS, Library-Mirrors, Triaged labels.

[peter-ahe-google]

Changed the title to: "Mirrors and runtime information for current function".

[peter-ahe-google]

Mike, it sounds to me that you're looking for a new method in the mirror API that could look something like this:

/**
  * Returns a [MethodMirror] corresponding to the closure [function].
  *
  * If [function] is the implicit closure of a top-level, static,
  * or instance method, this method returns a MethodMirror on that method.
  *
  * Otherwise, this method throws [ArgumentError].
  */
MethodMirror reflectFunction(Function function);

Am I understanding you correctly?

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cc @gbracha.
Removed Area-Dart2JS label.
Added Area-Library label.

[DartBot]

This comment was originally written by @a14n

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His original question on stackoverflow : http://stackoverflow.com/questions/17741543/how-do-i-get-a-methodmirror-for-the-current-function

I think he is looking for an equivalent of the JS "arguments.callee" returning a MethodMirror.

[DartBot]

This comment was originally written by off...@mikemitterer.at

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Yeah #­6 is almost right. The difference to callee is that it gives you a reference to the calling function - I just need it's name. If I have the name - sure, then #­5 would be necessary.
I want to be able to get access to @­Path in the function where it is notated and for this I need to know what the name of the calling function is (programmatically) .

BTW: #­2 File name, Line number usw. would also be very helpful

[peter-ahe-google]

I doubt we will expose access to anything like JavaScript's arguments.callee in Dart.

[DartBot]

This comment was originally written by @mezoni

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I doubt we will expose access to anything like JavaScript's arguments.callee in Dart.

Something similar.

void foo(int a, int b) {
  Function callee = Function.callee();
  var args = Function.arguments();
  print(Function.getName(callee));
  print(args['a']);
}

abstract class Function {
  external static Map<Symbol, dynamic> arguments();

  external static Function callee();

  external static Symbol getName(Function function);

  external static apply(Function function, List positionalArguments,
    [Map<Symbol, dynamic> namedArguments]);
}

Or maybe another class for this purpose.

[gbracha]

FWIW

MethodMirror methodMirror = reflect(functionOne).function;

should work, because reflecting a function gives you a ClosureMirror, which is a specialization of InstanceMirror that supports the function accessor. We are shaking out the bugs in this area, so it might not work in JS yet, or even in every case on the VM (but it does for a top level function).

So I don't think reflectFunction is necessary.

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Removed Type-Defect label.
Added Type-Enhancement, Accepted labels.

[gbracha]

This now works as advertised in the VM. So I'm closing the bug.

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Set owner to @gbracha.
Added WontFix label.