From: "Mauricio Fernández" <mfp@...>
Date: 2005-08-10T18:38:19+09:00
Subject: Re: [BUG] bug in variable assignment

On Wed, Aug 10, 2005 at 10:40:15AM +0900, Yukihiro Matsumoto wrote:
> In message "Re: [BUG] bug in variable assignment"
>     on Wed, 10 Aug 2005 09:52:12 +0900, Yukihiro Matsumoto <matz@ruby-lang.org> writes:
> 
> |You shouldn't _fix_ this.  Formal arguments to the anonymous function
> |would not modify the external variables even when they are used outside.
> 
> Instead we should fix optional arguments and rest arguments NOT to
> modify outside variables.

I see, I picked the wrong semantics.
The above should also apply to block arguments then.

$ ./ruby -ve "b=1; ->(&b){}.call; p b"
ruby 1.9.0 (2005-08-10) [i686-linux]
nil


Index: parse.y
===================================================================
RCS file: /src/ruby/parse.y,v
retrieving revision 1.402
diff -p -u -r1.402 parse.y
--- parse.y	10 Aug 2005 01:39:23 -0000	1.402
+++ parse.y	10 Aug 2005 09:18:04 -0000
@@ -4205,7 +4205,15 @@ f_block_arg	: blkarg_mark tIDENTIFIER
 			    yyerror("block argument must be local variable");
 			else if (!dyna_in_block() && local_id($2))
 			    yyerror("duplicated block argument name");
-			$$ = dyna_in_block() ? assignable($2, 0) : NEW_BLOCK_ARG($2);
+			    
+			if (dyna_in_block()) {
+			    shadowing_lvar($2);
+			    dyna_var($2);
+			    $$ = assignable($2, 0); 
+			}
+			else {
+			    $$ = NEW_BLOCK_ARG($2);
+			}
 		    /*%
 			$$ = $2;
 		    %*/
Index: test/ruby/test_lambda.rb
===================================================================
RCS file: /src/ruby/test/ruby/test_lambda.rb,v
retrieving revision 1.1
diff -p -u -r1.1 test_lambda.rb
--- test/ruby/test_lambda.rb	8 Aug 2005 23:24:29 -0000	1.1
+++ test/ruby/test_lambda.rb	10 Aug 2005 09:18:04 -0000
@@ -36,9 +36,9 @@ class TestLambdaParameters < Test::Unit:
     assert_equal(nil, ->(&b){ b }.call)
     foo { puts "bogus block " }
     assert_equal(1, ->(&b){ b.call }.call { 1 })
-    b = nil
+    b = 2
     assert_equal(1, ->(&b){ b.call }.call { 1 })
-    assert_not_nil(b)
+    assert_equal(2, b)
   end
 
   def foo
@@ -50,4 +50,16 @@ class TestLambdaParameters < Test::Unit:
     2.times ->(_){ a += 1 }
     assert_equal(a, 2)
   end
+
+  def test_var_shadowing
+    a = 0
+    _a, _b, _c, _d, _e, _f = lambda do 
+      b = c = d = e = 0
+      f = ->(a, b, c=1, *d, &e){ }
+      [->(){a}, ->(){b}, ->(){c}, ->(){d}, ->(){e}, f]
+    end.call
+    assert_equal([0,0,0,0,0], [_a[], _b[], _c[], _d[], _e[]])
+    _f.call(1,2,3,4,5) { }
+    assert_equal([0,0,0,0,0], [_a[], _b[], _c[], _d[], _e[]])
+  end
 end


$ ./ruby -we "b=1; ->(&b){}.call; p b"
-e:1: warning: shadowing outer local variable - b
1
$ ./ruby -w test/ruby/test_lambda.rb
test/ruby/test_lambda.rb:40: warning: shadowing outer local variable - b
test/ruby/test_lambda.rb:58: warning: shadowing outer local variable - a
test/ruby/test_lambda.rb:58: warning: shadowing outer local variable - b
test/ruby/test_lambda.rb:58: warning: shadowing outer local variable - c
test/ruby/test_lambda.rb:58: warning: shadowing outer local variable - d
test/ruby/test_lambda.rb:58: warning: shadowing outer local variable - e
Loaded suite test/ruby/test_lambda
Started
.......
Finished in 0.008198 seconds.

7 tests, 26 assertions, 0 failures, 0 errors

-- 
Mauricio Fernandez