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Feature #13979

Ruby doesn't give error on keyword arguments that you can't refer to

Added by asterite (Ary Borenszweig) about 2 years ago. Updated about 2 years ago.

Status:
Rejected
Priority:
Normal
Assignee:
-
Target version:
-
[ruby-core:83135]

Description

You can't use keywords as names for normal arguments. For example all of these give a syntax error:

def foo(class); end
def foo(def); end
def foo(if); end
# ... other keywords too

The reason is that there's no way to refer to these names because they are keywords.

However, we can use these names for keyword arguments. All of these work:

def foo(class: 1); end
def foo(def: 1); end
def foo(if: 1); end

But I think they should give a syntax error, because for example I can't refer to the argument "class" in the first line (same reason why the first snippet gives a syntax error).

History

#1

Updated by nobu (Nobuyoshi Nakada) about 2 years ago

  • Status changed from Open to Rejected
  • Description updated (diff)

Use Binding#local_variable_get.

#2

Updated by Eregon (Benoit Daloze) about 2 years ago

nobu (Nobuyoshi Nakada) Is there any value to support such keyword arguments?
I think an early error might be less surprising here.

On the callee side, I think it's a lot more practical to use **keyrest in such a case like keyrest.fetch(:class, 1).

Updated by asterite (Ary Borenszweig) about 2 years ago

Thank you nobu, I didn't know about Binding#local_variable_get

Updated by nobu (Nobuyoshi Nakada) about 2 years ago

Eregon (Benoit Daloze) wrote:

nobu (Nobuyoshi Nakada) Is there any value to support such keyword arguments?
I think an early error might be less surprising here.

I've heard the example that Rails (maybe ActiveSupport?) had used if: as short for "interface".
Binding#local_variable_get does not encourage to use such arguments.

Updated by ko1 (Koichi Sasada) about 2 years ago

Binding#local_variable_get does not encourage to use such arguments.

But Binding#local_variable_get is introduced for this purpose :p

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