Bug #11296: Proc#arity returns weird value for non-lambda proc with optional arguments

• Status: Rejected
• Assignee: -
• Target version: -
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN

[matz (Yukihiro Matsumoto)]

Proc.new(x=0){}.arity returns 0, not -1 unlike lambdas.
I don't remember if it's intentional or not. Anyone remember?

Matz.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Feedback

Proc.new(x=0){} raises an ArgumentError for me, in 1.8..2.3.

[Hanmac (Hans Mackowiak)]

i think matz means:

Proc.new(){|x=0|}.arity # => 0 
lambda {|x=0|}.arity # => -1 

[znz (Kazuhiro NISHIYAMA)]

I think #5694 and #7765 are related issues.

[matz (Yukihiro Matsumoto)]

Hans, thank you. That's what I meant.
Kazuhiro, #7765 suggests that seems intentional.
After hearing opnion from others, I will close the issue (unless meaningful discussion starts).

Matz.

[marcandre (Marc-Andre Lafortune)]

This is intentional, as per #5694 (note 22). It is not really related to #7765.

FWIW, I still believe it was not the best decision.

[matz (Yukihiro Matsumoto)]

• Status changed from Feedback to Closed

Marc-Andre, thank you for the info. You have made the issue clear.
Now I can safely close the issue.

Matz.

[usa (Usaku NAKAMURA)]

• Status changed from Closed to Rejected