Bug #10277: Ampersand to_proc issues

• Status: Rejected
• Assignee: -
• Target version: 2.2.0
• ruby -v: ruby 2.1.2p95 (2014-05-08 revision 45877) [x86_64-darwin13.0]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN

[jridgewell (Justin Ridgewell)]

I'm noticing weird inconsistencies when when returning a bound method in the #to_proc method when using &instance_object. When returning the bound method from #to_proc, it'll raise an error ("wrong argument type AmpersandMethod (expected Proc) (TypeError)", AmpersandMethod being my class name). However, if I explicitly #to_proc the bound method, everything works as normal. I've attached a small ruby script showing the problem.

This seems correct to me. The & operator expects to_proc to return an actual Proc. AmpersandMethod#to_proc does not return a Proc, it returns a Method.

In other words,

puts yielder(&AmpersandMethod.new.method(:mapper))
puts a.map(&AmpersandMethod.new.method(:mapper))

here to_proc on the given object returns a Proc.

puts yielder(&AmpersandMethod.new)
puts a.map(&AmpersandMethod.new)

here to_proc on the given object returns a Method, not a Proc.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Rejected

to_proc must return a Proc, not a Method.
They are different.