Error when pass named parameter into constructor

[DartBot]

This issue was originally filed by sharen...@gmail.com

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What steps will reproduce the problem?
Execute code:
class A {
  int foo;
  A(this.foo);
}

class B extends A {
  B(int foo) : super(foo) {}
}

main(){
  B b1 = new B(1); // ok
  B b2 = new B(foo:2); // Error
}

What is the expected output?
No Error.

What do you see instead?
'file:///C:/projects/dart_dandy/testNamendParams.dart': Error: line 12 pos 15: invalid arguments passed to constructor 'B' for class 'B'
  B b2 = new B(foo:2); // Error
              ^

What version of the product are you using? On what operating system?
Dart Editor bundle 64bit Version 0.1.0.201204200749, Build 6799 @­ Windows 7 64bit

I use named parameter to make code more readable. :)

[rakudrama]

Named arguments can only be used for optional arguments, e.g.

  B([int foo = 99]) : super(foo) {}

http://try.dartlang.org/s/_EM9

So we can go one of two places from here:
(1) close the issue as AsDesigned - your example is not a valid dart program.
(2) change the issue into a request for a new feature to allow named non-optional arguments.

[madsager]

Added AsDesigned label.

[DartBot]

This comment was originally written by share...@gmail.com

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My usage named parameter is guided by "Dart style guide" http://www.dartlang.org/articles/style-guide/

See the section about boolean parameters:
"""
AVOID boolean arguments unless their meaning is completely obvious.

Unlike other types, booleans are usually used in literal form. Things like numbers are usually wrapped in named constants, but we usually just pass around true and false directly. That can make callsites unreadable if it isn't clear what the boolean represents:

new Timer(true);
new Timer(false);
new ListBox(false, true, true);

Instead, consider using named arguments, named constructors, or named constants to clarify what the call is doing.

new Timer.oneShot();
new Timer.repeating();
new ListBox(scroll: SCROLL_BOTH, showScrollbars: true);
""" end quote

There are three options:
(1) note only default parameters in styleguide.
(2) set this section of styleguide obsolete
(3) make it work
:)

I preffer your option (2) and my option (3).

Thanks.

[DartBot]

This comment was originally written by sharenk...@gmail.com

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Just compare
(1)
_vram = new RandomAccessMemory("VRAM", 0x2000, 0x1F00, 0x0FFF);
and
(2)
_vram = new RandomAccessMemory("VRAM", offset:0x2000, size:0x1F00, addressMask:0x0FFF);

(2) is much more understanable, IMHO.