require 'facet/symbol/to_proc'
[[1,2], [], [1,2,3]].map(&:length) #line 1 Blows up re undefined method
length for Fixnum?
["ab", "", "abc"].map(&:length) #line 2 => [2, 0, 3] but this works fine
Why does the first line fail by trying to call method length on Fixnum?
Shouldn't it be calling length on Array (which is defined) and thus return
[2,0,3] ? Note the next line behaves as I'd expect, but for Strings.
What's happening?
I get the error "wrong argument type Symbol (expected Proc)
(TypeError)", not undefined method.
Hi --
On Wed, 8 Mar 2006, Brian Buckley wrote:
require 'facet/symbol/to_proc'
[[1,2], [], [1,2,3]].map(&:length) #line 1 Blows up re undefined method
length for Fixnum?["ab", "", "abc"].map(&:length) #line 2 => [2, 0, 3] but this works fine
Why does the first line fail by trying to call method length on Fixnum?
Shouldn't it be calling length on Array (which is defined) and thus return
[2,0,3] ? Note the next line behaves as I'd expect, but for Strings.What's happening?
I'm only guessing but could it be flattening the outer array?
David
--
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)
"Ruby for Rails" chapters now available
from Manning Early Access Program! http://www.manning.com/books/black
I figured it out! I figured it out!
theorizing that to_proc was implemented thusly:
class Symbol
def to_proc
lambda { |obj, *args| obj.send(self, *args) }
end
end
which would be fine, except, ba bum bum! you have an array of arrays! map or each or someone is passing it via yield which is sending :length.to_proc.call two args which turns into 1.send(:length, 2)
On Mar 7, 2006, at 1:09 PM, Brian Buckley wrote:
require 'facet/symbol/to_proc'
[[1,2], [], [1,2,3]].map(&:length) #line 1 Blows up re undefined method
length for Fixnum?["ab", "", "abc"].map(&:length) #line 2 => [2, 0, 3] but this works fine
Why does the first line fail by trying to call method length on Fixnum?
Shouldn't it be calling length on Array (which is defined) and thus return
[2,0,3] ? Note the next line behaves as I'd expect, but for Strings.What's happening?
Ack, nevermind. I'm a silly person, ignore me.
On 3/7/06, Matthew Moss <matthew.moss.coder@gmail.com> wrote:
I get the error "wrong argument type Symbol (expected Proc)
(TypeError)", not undefined method.