Bug #5746: Proc#curry too strict about lambda's arity.

• Status: Closed
• Assignee: marcandre (Marc-Andre Lafortune)
• Target version: -
• ruby -v: -

[marcandre (Marc-Andre Lafortune)]

Currently, Proc#curry raises an error when you attempt to curry a lambda with optional (but limited) arguments:

l = ->(arg = 42) {}
l.curry(1) # => ArgumentError: wrong number of arguments (1 for 0)

Note that Proc#curry behaves correctly if the Proc was created from a method, even though arguments are treated the same way:

def Object.foo(arg = 42); end
m = Object.method(:foo).to_proc
m.class # => Proc, same as 'l'
m.lambda? # => true, same as 'l'
m.curry(1) # => curried proc

Referring to my evaluation method, my proposed fix passes SST:
a) usefulness: way more useful, as it makes it possible to do something that is not currently possible
b) consistency: makes it consistent with equivalent method
c) intuitiveness and d) performance: similar

It is straightforward (but not obvious), as it passes NIT (but not ODT).

This bug is a consequence of the redmine issue 5694; this will be fixed automatically when 5694 is fixed.

[matz (Yukihiro Matsumoto)]

Hi,

In message "Re: [ruby-core:41594] [ruby-trunk - Bug #5746][Open] Proc#curry too strict about lambda's arity."
on Mon, 12 Dec 2011 02:08:08 +0900, Marc-Andre Lafortune [e-mail] writes:

|Currently, Proc#curry raises an error when you attempt to curry a lambda with optional (but limited) arguments:
|
| l = ->(arg = 42) {}
| l.curry(1) # => ArgumentError: wrong number of arguments (1 for 0)

In my opinion, #curry should not rely on #arity at all. Even after
proposed fix, it accepts l.curry(3) which is wrong. It should use
more reliable information such as #parameters.

						matz.

Hi,

On Sun, Dec 11, 2011 at 4:06 PM, Yukihiro Matsumoto [e-mail] wrote:

Hi,

In message "Re: [ruby-core:41594] [ruby-trunk - Bug #5746][Open] Proc#curry too strict about lambda's arity."
   on Mon, 12 Dec 2011 02:08:08 +0900, Marc-Andre Lafortune [e-mail] writes:

|Currently, Proc#curry raises an error when you attempt to curry a lambda with optional (but limited) arguments:
|
|    l

[ko1 (Koichi Sasada)]

• Assignee set to mame (Yusuke Endoh)

[shyouhei (Shyouhei Urabe)]

• Status changed from Open to Assigned

[mame (Yusuke Endoh)]

• Assignee changed from mame (Yusuke Endoh) to matz (Yukihiro Matsumoto)

This issue is blocked by #5694 which is assigned to matz.
So I'm assigning this to matz.

--
Yusuke Endoh [e-mail]

[ko1 (Koichi Sasada)]

• Assignee changed from matz (Yukihiro Matsumoto) to nobu (Nobuyoshi Nakada)

[marcandre (Marc-Andre Lafortune)]

• Assignee changed from nobu (Nobuyoshi Nakada) to marcandre (Marc-Andre Lafortune)

[marcandre (Marc-Andre Lafortune)]

• Status changed from Assigned to Closed

This was fixed when #5694 was resolved.