On Apr 24, 2013 10:53 PM, "marcandre (Marc-= Andre Lafortune)" <ruby-= core@marc-andre.ca> wrote:

Issue #8040 has been updated by marcandre (Marc-Andre Lafortune).

Any hope of getting this in time for next patchlevel release?
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Bug #8040: Unexpect behavior when using keyword arguments
https://bugs.ruby-lang.org/issues/8040#change-38882

Author: pabloh (Pablo Herrero)
Status: Assigned
Priority: Normal
Assignee: mame (Yusuke Endoh)
Category:
Target version:
ruby -v: 2.0.0-p0
Backport:

=3Dbegin
There is an odd behavior when calling methods with the new keyword argument= s syntax, when you have a method defined with mandatory arguments that also= takes options, like this:

=A0 def foo value, **keywords
=A0 =A0 puts [value,keywords].inspect
=A0 end

=A0 foo("somthing") #This works
=A0 foo("somthing", key: 'value') #This also works

=A0 foo(Hash.new(something: 'else')) #This raises 'ArgumentErro= r: wrong number of arguments (0 for 1)'

This feels weird regardless the fact that keyword arguments are a Hash at t= he bottom, since you ARE PASSING an argument.

Other side effect from this, is that when you call the method ((|foo|)) wit= h a single argument, you can't anticipate how many argument you will be= actually passing at runtime unless you know beforehand the argument's = class.

What's maybe even more concerning is the fact than this happens even wh= en you pass an argument which class derives from Hash:

=A0 class MyDirectory < Hash; end

=A0 foo(MyDirectory.new(something: 'else')) #This also raises '= ArgumentError: wrong number of arguments (0 for 1)'

Besides finding this behavior surprising, I think this could also possibly = lead to old code been unexpectedly broken when updating old methods that ta= kes options to the new syntax.

For example if you have this code:

=A0 def foo_with_options argument, options =3D {}
=A0 =A0 #Do some stuff with options
=A0 end

=A0 #And at someplace else...

=A0 my_hash_thingy =3D Hash.new
=A0 foo_with_options(my_hash_thingy) #Only passing mandatory argument, with= no options, works fine.

When updating to the new syntax:

=A0 def foo_with_options argument, an_option: 'value1', another_opt= ion: 'value2'
=A0 =A0 #Do some stuff with options
=A0 end

=A0 #And at someplace else...

=A0 my_hash_thingy =3D Hash.new
=A0 foo_with_options(my_hash_thingy) #Only passing mandatory argument, with= no options, doesn't work anymore.
=3Dend

--
http://bugs.ruby-l= ang.org/