From: "Gerardo Santana Gómez Garrido" <gerardo.santana@...>
Date: 2006-03-25T12:38:02+09:00
Subject: [PATCH] to_str, to_s and StringValue

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If I understand correctly, StringValue is a way for writing duck-type
friendly code.

StringValue calls rb_str_to_str(obj) for trying to get a String object
from obj, but looks for to_str only, not to_s. That was a problem for
me when receiving Date objects because Date doesn't have to_str.

Attached is patch for date.rb (lib_date_rb.patch)

But while I was at it, I found only 7 references to to_str vs. 34
references to to_s.

Only these objects implement to_str:

*rb_cNameErrorMesg
rb_cDLCPtr
rb_cString

and all of them have to_s, except rb_cNameErrorMesg. So, what's the
point of looking for to_str in rb_str_to_str?

Attached are the two patches needed (string_c.patch and error_c.patch)
to change this. I'm changing to_str to to_s in string.c and aliasing
to_str to to_s in error.c, for not breaking existing code, just in
case.

Thanks in advance for any clarification if I'm misunderstanding something.
--
Gerardo Santana
"Between individuals, as between nations, respect for the rights of
others is peace" - Don Benito Ju=E1rez
http://santanatechnotes.blogspot.com/

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? lib_date_rb.patch
Index: lib/date.rb
===================================================================
RCS file: /src/ruby/lib/date.rb,v
retrieving revision 1.27
diff -u -r1.27 date.rb
--- lib/date.rb	29 Oct 2005 08:03:46 -0000	1.27
+++ lib/date.rb	25 Mar 2006 02:00:11 -0000
@@ -1022,6 +1022,7 @@
   #
   # The format used is YYYY-MM-DD.
   def to_s() strftime end
+  alias_method :to_str, :to_s
 
   # Dump to Marshal format.
   def _dump(limit) Marshal.dump([@ajd, @of, @sg], -1) end

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Index: string.c
===================================================================
RCS file: /src/ruby/string.c,v
retrieving revision 1.245
diff -u -r1.245 string.c
--- string.c	24 Mar 2006 12:14:18 -0000	1.245
+++ string.c	25 Mar 2006 03:04:09 -0000
@@ -227,7 +227,7 @@
 VALUE
 rb_str_to_str(VALUE str)
 {
-    return rb_convert_type(str, T_STRING, "String", "to_str");
+    return rb_convert_type(str, T_STRING, "String", "to_s");
 }
 
 static void

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Index: error.c
===================================================================
RCS file: /src/ruby/error.c,v
retrieving revision 1.121
diff -u -r1.121 error.c
--- error.c	13 Feb 2006 04:53:21 -0000	1.121
+++ error.c	25 Mar 2006 03:27:30 -0000
@@ -975,6 +975,7 @@
     rb_define_singleton_method(rb_cNameErrorMesg, "!", name_err_mesg_new, 3);
     rb_define_method(rb_cNameErrorMesg, "==", name_err_mesg_equal, 1);
     rb_define_method(rb_cNameErrorMesg, "to_str", name_err_mesg_to_str, 0);
+    rb_define_alias(rb_cNameErrorMesg, "to_s", "to_str");
     rb_define_method(rb_cNameErrorMesg, "_dump", name_err_mesg_to_str, 1);
     rb_define_singleton_method(rb_cNameErrorMesg, "_load", name_err_mesg_load, 1);
     rb_eNoMethodError = rb_define_class("NoMethodError", rb_eNameError);

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