I'd noticed that too. I thought Strings were actually NSStrings. Ricky On Apr 18, 2011, at 9:52 AM, Petr Kaleta wrote:

Btw: it seems, that something has changed in ruby primitives classes implementation, described in here http://www.macruby.org/documentation/tutorial.html (this example http://cl.ly/2Y382r0w331O230z1Q3D) because "foo".class is not NSCFString but String http://cl.ly/110Y0O0D1k3y1G2e2j2X

- Petr

On Apr 18, 2011, at 3:45 PM, Petr Kaleta wrote:

...

Hi I'm a little bit confused about basic ruby classes implementation. Ruby Hash is internally implemented as NSDictionary/NSMutableDictionary? So for example if I need to implement hash table, I can use ruby Hash? So the performance will be exactly same compared to NSDictionary?

- Petr _______________________________________________ MacRuby-devel mailing list MacRuby-devel@lists.macosforge.org http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel

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Actually, it's quite a bit more complicated than that. NSString, NSDictionary, and NSArray are class clusters. In practice, you are never actually dealing with an "NSString", but rather a specialized subclass in the class cluster. Originally, String in MacRuby was implemented using NSCFString (one of NSString's cluster members) as a backing store, but around 0.6 or 0.7 (my memory is foggy...Laurent and Vincent will know more) Ruby's string implementation was changed so that now Ruby's string class is completely custom, but it is a valid member of the NSString cluster (i.e. it is a valid concrete subclass of NSString and NSMutableString). What does this mean? Well, the practical implication is that all Ruby Strings are valid NSStrings, but not all NSStrings are valid Ruby strings. That is, if you are interfacing with an Obj-C library that expects an NSString or NSMutable string argument, you are safe to pass in any string created in Ruby. However, if you are interfacing with an Obj-C library that returns an NSString, you will need to turn this into a Ruby string before you do Ruby-ish things too it. (If you're just turning around and pushing that string back into an Obj-C library method that expects an NSString, you can skip that step. Likewise, if you're only doing simple things like "puts"-ing you can keep it as an NSString.) Probably the most confusing thing about the situation as it currently stands, is that MacRuby will insist that NSStrings are just "String"s, which they aren't...quite... The issue is that if you need a string, sometimes an NSString is sufficient and in those cases you'd want the NSString to report itself as being the same as a String. In other cases, however, they are different beasts. We'll probably have to come up with a better solution, though, before the 1.0 release. If you can make more sense of code than of words, here it is in code: ----- irb(main):001:0> ns = NSString.stringWithString('Test') => "Test" irb(main):002:0> ns.class => String irb(main):003:0> ns.class.ancestors => [String, NSMutableString, NSString, Comparable, NSObject, Kernel] irb(main):004:0> puts ns Test => nil irb(main):005:0> ns.gsub!(/T/, 't') RuntimeError: can't modify frozen/immutable string irb(main):006:0> rb = String.new(ns) => "Test" irb(main):007:0> rb.class => String irb(main):008:0> rb.class.ancestors => [String, NSMutableString, NSString, Comparable, NSObject, Kernel] irb(main):009:0> puts rb Test => nil irb(main):010:0> rb.gsub!(/T/, 't') => "test" ----- Cheers, Josh On Mon, Apr 18, 2011 at 1:40 PM, Joe West <mrjoewest+macruby-devel@gmail.com

wrote:

On Mon, Apr 18, 2011 at 10:40 AM, Ricky Chilcott <ricky@rickychilcott.com> wrote:

...

I'd noticed that too. I thought Strings were actually NSStrings.

They are NSMutableStrings/NSStrings underneath:

irb(main):013:0> "string".class.ancestors => [String, NSMutableString, NSString, Comparable, NSObject, PP::ObjectMixin, Kernel]

And hashes are similarly NSMutableDictionary/NSDictionary:

irb(main):015:0> {}.class.ancestors => [Hash, NSMutableDictionary, NSDictionary, Enumerable, NSObject, PP::ObjectMixin, Kernel]

Couldn't say for sure, but seems like a good move to improve consistency/compatibility with non-MacRuby code and gems and the like.

Joe _______________________________________________ MacRuby-devel mailing list MacRuby-devel@lists.macosforge.org http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel