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Bug #8641

closed

Enumerator size argument is either mis-documented or should accept any callable

Added by avdi (Avdi Grimm) almost 11 years ago. Updated over 10 years ago.

Status:
Closed
Assignee:
marcandre (Marc-Andre Lafortune)
Target version:
2.1.0
ruby -v:
ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-linux]
Backport:
1.9.3: UNKNOWN, 2.0.0: UNKNOWN
[ruby-core:56032]

Description

I ran into this while wrapping Enumerators around Queues. The Enumerator docs state:

  • The optional parameter can be used to specify how to calculate the size
  • in a lazy fashion (see Enumerator#size). It can either be a value or
  • a callable object.

However:

require 'thread'
q = Queue.new
eq = Enumerator.new(q.method(:size)) do |y|
loop do
y << q.pop
end
end
eq.size # =>

~> -:3:in `initialize': no implicit conversion of Method into Integer (TypeError)

~> from -:3:in `new'

~> from -:3:in `'

It looks like the size can't be any callable; it must be Proc a or an Integer. The code uses rb_obj_is_proc().

Instinctively I'd say that the documentation has it right and it ought to take any callable. But if there's some reason it's limited to Procs, the docs should be changed.

If anyone can point me in the right direction I'm happy to do the legwork on this.

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