* array.c (rb_ary_s_try_convert): a new class method to convert

object or nil if it's not target-type.  this mechanism is used
  to convert types in the C implemented methods.

* hash.c (rb_hash_s_try_convert): ditto.

* io.c (rb_io_s_try_convert): ditto.

* re.c (rb_reg_s_try_convert): ditto.

* string.c (rb_str_s_try_convert): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@13251 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,17 @@
+Sat Aug 25 02:08:45 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* array.c (rb_ary_s_try_convert): a new class method to convert
+	  object or nil if it's not target-type.  this mechanism is used
+	  to convert types in the C implemented methods.
+
+	* hash.c (rb_hash_s_try_convert): ditto.
+
+	* io.c (rb_io_s_try_convert): ditto.
+
+	* re.c (rb_reg_s_try_convert): ditto.
+
+	* string.c (rb_str_s_try_convert): ditto.
+
 Sat Aug 25 00:49:44 2007  Koichi Sasada  <ko1@atdot.net>
 
 	* benchmark/bm_loop_generator.rb: added.

array.c

@@ -243,6 +243,23 @@ rb_check_array_type(VALUE ary)
     return rb_check_convert_type(ary, T_ARRAY, "Array", "to_ary");
 }
 
+/*
+ *  call-seq:
+ *     Array.try_convert(obj) -> array or nil
+ *
+ *  Try to convert <i>obj</i> into an array, using to_ary method.
+ *  Returns converted array or nil if <i>obj</i> cannot be converted
+ *  for any reason.
+ *
+ *     Array.try_convert([1])   # => [1]
+ *     Array.try_convert("1")   # => nil
+ */
+static VALUE
+rb_ary_s_try_convert(VALUE dummy, VALUE ary)
+{
+    return rb_check_array_type(ary);
+}
+
 /*
  *  call-seq:
  *     Array.new(size=0, obj=nil)
@@ -2932,6 +2949,7 @@ Init_Array(void)
 
     rb_define_alloc_func(rb_cArray, ary_alloc);
     rb_define_singleton_method(rb_cArray, "[]", rb_ary_s_create, -1);
+    rb_define_singleton_method(rb_cArray, "try_convert", rb_ary_s_try_convert, 1);
     rb_define_method(rb_cArray, "initialize", rb_ary_initialize, -1);
     rb_define_method(rb_cArray, "initialize_copy", rb_ary_replace, 1);
 

hash.c

@@ -336,6 +336,23 @@ to_hash(VALUE hash)
     return rb_convert_type(hash, T_HASH, "Hash", "to_hash");
 }
 
+/*
+ *  call-seq:
+ *     Hash.try_convert(obj) -> hash or nil
+ *
+ *  Try to convert <i>obj</i> into a hash, using to_hash method.
+ *  Returns converted hash or nil if <i>obj</i> cannot be converted
+ *  for any reason.
+ *
+ *     Hash.try_convert({1=>2})   # => {1=>2}
+ *     Hash.try_convert("1=>2")   # => nil
+ */
+static VALUE
+rb_hash_s_try_convert(VALUE dummy, VALUE hash)
+{
+    return rb_check_convert_type(hash, T_HASH, "Hash", "to_hash");
+}
+
 static int
 rb_hash_rehash_i(VALUE key, VALUE value, st_table *tbl)
 {
@@ -2536,6 +2553,7 @@ Init_Hash(void)
 
     rb_define_alloc_func(rb_cHash, hash_alloc);
     rb_define_singleton_method(rb_cHash, "[]", rb_hash_s_create, -1);
+    rb_define_singleton_method(rb_cHash, "try_convert", rb_hash_s_try_convert, 1);
     rb_define_method(rb_cHash,"initialize", rb_hash_initialize, -1);
     rb_define_method(rb_cHash,"initialize_copy", rb_hash_replace, 1);
     rb_define_method(rb_cHash,"rehash", rb_hash_rehash, 0);

io.c

@@ -242,6 +242,23 @@ rb_io_check_io(VALUE io)
     return rb_check_convert_type(io, T_FILE, "IO", "to_io");
 }
 
+/*
+ *  call-seq:
+ *     IO.try_convert(obj) -> io or nil
+ *
+ *  Try to convert <i>obj</i> into an IO, using to_io method.
+ *  Returns converted IO or nil if <i>obj</i> cannot be converted
+ *  for any reason.
+ *
+ *     IO.try_convert(STDOUT)     # => STDOUT
+ *     IO.try_convert("STDOUT")   # => nil
+ */
+static VALUE
+rb_io_s_try_convert(VALUE dummy, VALUE io)
+{
+    return rb_io_check_io(io);
+}
+
 static void
 io_unread(rb_io_t *fptr)
 {
@@ -5708,6 +5725,7 @@ Init_IO(void)
     rb_define_singleton_method(rb_cIO, "read", rb_io_s_read, -1);
     rb_define_singleton_method(rb_cIO, "select", rb_f_select, -1);
     rb_define_singleton_method(rb_cIO, "pipe", rb_io_s_pipe, 0);
+    rb_define_singleton_method(rb_cIO, "try_convert", rb_io_s_try_convert, 1);
 
     rb_define_method(rb_cIO, "initialize", rb_io_initialize, -1);
 

re.c

@@ -2034,6 +2034,22 @@ rb_check_regexp_type(VALUE re)
     return rb_check_convert_type(re, T_REGEXP, "Regexp", "to_regexp");
 }
 
+/*
+ *  call-seq:
+ *     Regexp.try_convert(obj) -> re or nil
+ *
+ *  Try to convert <i>obj</i> into a Regexp, using to_regexp method.
+ *  Returns converted regexp or nil if <i>obj</i> cannot be converted
+ *  for any reason.
+ *
+ *     IO.try_convert(/re/)      # => /re/
+ *     IO.try_convert("re")      # => nil
+ */
+static VALUE
+rb_reg_s_try_convert(VALUE dummy, VALUE re)
+{
+    return rb_check_regexp_type(re);
+}
 
 /*
  *  call-seq:
@@ -2422,6 +2438,7 @@ Init_Regexp(void)
     rb_define_singleton_method(rb_cRegexp, "escape", rb_reg_s_quote, -1);
     rb_define_singleton_method(rb_cRegexp, "union", rb_reg_s_union, -1);
     rb_define_singleton_method(rb_cRegexp, "last_match", rb_reg_s_last_match, -1);
+    rb_define_singleton_method(rb_cRegexp, "try_convert", rb_reg_s_try_convert, 1);
 
     rb_define_method(rb_cRegexp, "initialize", rb_reg_initialize_m, -1);
     rb_define_method(rb_cRegexp, "initialize_copy", rb_reg_init_copy, 1);

string.c

@@ -615,6 +615,23 @@ rb_check_string_type(VALUE str)
     return str;
 }
 
+/*
+ *  call-seq:
+ *     String.try_convert(obj) -> string or nil
+ *
+ *  Try to convert <i>obj</i> into a String, using to_str method.
+ *  Returns converted regexp or nil if <i>obj</i> cannot be converted
+ *  for any reason.
+ *
+ *     String.try_convert("str")     # => str
+ *     String.try_convert(/re/)      # => nil
+ */
+static VALUE
+rb_str_s_try_convert(VALUE dummy, VALUE str)
+{
+    return rb_check_string_type(str);
+}
+
 VALUE
 rb_str_substr(VALUE str, long beg, long len)
 {
@@ -4877,6 +4894,7 @@ Init_String(void)
     rb_cString  = rb_define_class("String", rb_cObject);
     rb_include_module(rb_cString, rb_mComparable);
     rb_define_alloc_func(rb_cString, str_alloc);
+    rb_define_singleton_method(rb_cString, "try_convert", rb_str_s_try_convert, 1);
     rb_define_method(rb_cString, "initialize", rb_str_init, -1);
     rb_define_method(rb_cString, "initialize_copy", rb_str_replace, 1);
     rb_define_method(rb_cString, "<=>", rb_str_cmp_m, 1);