Hi Caio,
You found out an exception :) As you know, NSArray responds to -count which
simply return the number of elements it contains. But Ruby Array defines #count
which has different semantics.
To not conflict with NSArray, the Ruby #count is only defined on Ruby arrays.
However, I do not understand where #count is used in your snippet. Is it used
in Pathname?
Laurent
On Oct 4, 2010, at 12:14 AM, Caio Chassot wrote:
> Hi all,
>
> Code first:
>
> cocoa_array = NSArray.new
> ruby_array = []
>
> puts ruby_array.count # => 0
> puts ruby_array.count { true } # => 0
> puts ruby_array.count("whatever") # => 0
>
> puts cocoa_array.count # => 0
> puts cocoa_array.count { true } # => 0 # unknown: warning: passing a
> block to an Objective-C method - will be ignored
> puts cocoa_array.count("whatever") # => wrong number of arguments (1 for
> 0) (ArgumentError)
>
> I originally ran into this issue in the following code, where the fact that
> we have an NSArray, and not a ruby array ends up concealed by the bajillion
> of ruby-ish method calls such as compact and map:
>
> paths_from_clipboard = NSPasteboard.generalPasteboard.pasteboardItems
> .map { |pbi | pbi.stringForType('public.file-url') }.compact
> .map { |url | NSURL.URLWithString(url).path }
> .map { |path| Pathname.new(path) }
>
>
> Full, pretty and colorful version: http://gist.github.com/602174
>
>
> What's going on there is that NSArrays (but not NSMutableArrays) will use the
> vanilla Cocoa's count method.
>
> So I'm resorting to doing:
>
> Array.new(SomeCocoaClass.withAMethodThatReturnsAnNSArray)
>
>
> I wonder, is this a bug or "works as designed"?
>
>
>
>
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> MacRuby-devel@lists.macosforge.org
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