From: "Jürgen Mangler" <juergen.mangler@...>
Date: 2004-12-28T17:06:57+09:00
Subject: Re: Extensions, Internal

myObj.text.gsub!(/a/,"b") will not alter the string returned by #text, 
because it returns a duplicated value from inside an extension. Sorry i 
can't explain it better.

think of something like:

VALUE rbxs_node_text_get(VALUE self) {
   rbxs_node *prbxs;

   Data_Get_Struct(self, rbxs, prbxs);
 
return(rb_str_new2(CONVERT_FROM_SOME_STRING_FORMAT(prbxs->node->content)));
}

VALUE rbxs_node_text_set(VALUE self, VALUE text) {
   rbxs_node *prbxs;

   Data_Get_Struct(self, rbxs, prbxs);

   setSomeStrangeTextFormat(prbxs->node->content,STR2CSTR(text));
}

when calling #gsub! on something that rbxs_node_text_get returns, it 
just don't alters the object it is called on, because it can't. Content 
can only be set through setSomeStrangeTextFormat

Maybe i missed something important, but after discussing a bit on 
#ruby-lang, someone came up with

"you could also create a wrapper string which has .gsub! and so on 
replaced with special versions that go through the setter"

which seemed somehow ... uncool to me.

I though that maybe I can tell a string, what to call to deliver 
something back (in this case rbxs_node_text_set). A callback function.
(Described in the first detail)

Sorry for my bad english.

J�rgen

Yukihiro Matsumoto wrote:
> Hi,
> 
> In message "Re: Extensions, Internal"
>     on Tue, 28 Dec 2004 14:54:50 +0900, J�rgen Mangler <juergen.mangler@univie.ac.at> writes:
> 
> |rb_define_method(cSimpleNode, "text",    rbxs_node_text_get, 0);
> |rb_define_method(cSimpleNode, "text=",   rbxs_node_text_set, 1);
> |
> |I've to return duplicates of the string, because the string format is 
> |incompatible/the string can only be set by calling a function. So a 
> |gsub! will not work as expected.
> 
> I'm afraid I don't understand what you want.  What do you expect for a
> gsub! to work?
> 
> 							matz.
> 
>