From: nobu.nakada@...
Date: 2003-06-03T10:24:22+09:00
Subject: [ruby-dev:20316] Re: local variable and local variable in block behave differently

なかだです。

ruby-talkに戻るべきなのかも知れませんが、途中経過を説明するのが
めんどくさいのでdevへ。

At Sat, 31 May 2003 00:43:02 +0900,
Yukihiro Matsumoto wrote:
> |> 1.times do
> |>   if false
> |>     a = ""
> |>   else
> |>     1.times { a = "a" }
> |>   end
> |>   puts defined? a # => local-variable(in-block)
> |>   puts a          # => nil
> |> end
> |
> |OK, that's weird... I would have thought that the assignment to 'a' in the
> |inner block would have bound to the 'a' brought into existence in the outer
> |block, but it hasn't.
> 
> Maybe a bug.  Let me check.

At Mon, 02 Jun 2003 22:23:17 +0900,
まつもと wrote:
> 「ブロックローカル変数の実際の初期化は最も近いブロックの先頭
> で行われる」ってのは良さげに聞こえますね。問題あるかな？

今のところ思い付くのは、local_variablesの動作が変わってしまうと
いうことですが。

とりあえず、http://nokada.jin.gr.jp/ruby/test_unpassed_dvar.rb
のテストは通るようになります。

* parse.y (cmd_brace_block, do_block, brace_block): initialize block
  variables at the beginning of the block.  [ruby-talk:72521]

Index: parse.y
===================================================================
RCS file: /cvs/ruby/src/ruby/parse.y,v
retrieving revision 1.275
diff -u -2 -p -r1.275 parse.y
--- parse.y	31 May 2003 09:11:12 -0000	1.275
+++ parse.y	2 Jun 2003 23:54:36 -0000
@@ -166,4 +166,5 @@ static struct RVarmap *dyna_push();
 static void dyna_pop();
 static int dyna_in_block();
+static NODE *dyna_init();
 
 static void top_local_init();
@@ -646,9 +647,9 @@ cmd_brace_block	: tLBRACE_ARG
 			$<num>1 = ruby_sourceline;
 		    }
-		  opt_block_var
+		  opt_block_var {$<vars>$ = ruby_dyna_vars;}
 		  compstmt
 		  '}'
 		    {
-			$$ = NEW_ITER($3, 0, $4);
+			$$ = NEW_ITER($3, 0, dyna_init($5, $<vars>4));
 			nd_set_line($$, $<num>1);
 			dyna_pop($<vars>2);
@@ -1715,9 +1716,9 @@ do_block	: kDO_BLOCK
 			$<num>1 = ruby_sourceline;
 		    }
-		  opt_block_var
+		  opt_block_var {$<vars>$ = ruby_dyna_vars;}
 		  compstmt
 		  kEND
 		    {
-			$$ = NEW_ITER($3, 0, $4);
+			$$ = NEW_ITER($3, 0, dyna_init($5, $<vars>4));
 			nd_set_line($$, $<num>1);
 			dyna_pop($<vars>2);
@@ -1778,8 +1779,8 @@ brace_block	: '{'
 			$<num>1 = ruby_sourceline;
 		    }
-		  opt_block_var
+		  opt_block_var {$<vars>$ = ruby_dyna_vars;}
 		  compstmt '}'
 		    {
-			$$ = NEW_ITER($3, 0, $4);
+			$$ = NEW_ITER($3, 0, dyna_init($5, $<vars>4));
 			nd_set_line($$, $<num>1);
 			dyna_pop($<vars>2);
@@ -1790,8 +1791,8 @@ brace_block	: '{'
 			$<num>1 = ruby_sourceline;
 		    }
-		  opt_block_var
+		  opt_block_var {$<vars>$ = ruby_dyna_vars;}
 		  compstmt kEND
 		    {
-			$$ = NEW_ITER($3, 0, $4);
+			$$ = NEW_ITER($3, 0, dyna_init($5, $<vars>4));
 			nd_set_line($$, $<num>1);
 			dyna_pop($<vars>2);
@@ -5655,4 +5656,19 @@ dyna_in_block()
 {
     return (lvtbl->dlev > 0);
+}
+
+static NODE *
+dyna_init(node, pre)
+    NODE *node;
+    struct RVarmap *pre;
+{
+    struct RVarmap *post = ruby_dyna_vars;
+    NODE *var;
+
+    if (!node || !post || pre == post) return node;
+    for (var = 0; post != pre && post->id; post = post->next) {
+	var = NEW_DASGN_CURR(post->id, var);
+    }
+    return block_append(var, node);
 }
 


-- 
--- 僕の前にBugはない。
--- 僕の後ろにBugはできる。
    中田 伸悦