[PATCH] block args w/ defaults (was Re: resolving lambda | ambiguity)

On Sat, May 24, 2008 at 4:06 PM, Eric Mahurin <[e-mail]>
wrote:

> On Fri, May 23, 2008 at 7:18 AM, ts <[e-mail]> wrote:
>
>> Eric Mahurin wrote:
>> > Is there any reason this idea couldn't be applied to head?
>>
>>  Try it on your personal version.
>>
>> Guy Decoux
>
>
> Here is a patch for handling optional args for blocks using this simple
> idea - use a "primary_value" instead of "arg_value" for the default values.
> I simply did some cutting and pasting for the argument definitions for "def"
> and changed "arg_value" to "primary_value".  It worked on the first try!
> Spent more time writing tests (included) than adding the new functionality.
>
> Matz, any chance this could be integrated for a trial period at least?  It
> shouldn't cause any compatibility issues.
>

For some reason, gmail attached my patch with base64 encoding.  A simple
cut-n-paste of the patch is below.  Also here would be a reasonable
ChangeLog entry:

* parse.y (block_param) : added alternatives for allowing arguments with
defaults.  These are identical to what is in f_args except f_block_optarg is
used instead of f_optarg.  f_block_optarg is the same as f_optarg except
primary_value is used instead of arg_value.
* sample/test.rb (assignment) : tested these new alternatives with defaults
for arguments.


Index: sample/test.rb
===================================================================
--- sample/test.rb    (revision 16568)
+++ sample/test.rb    (working copy)
@@ -296,6 +296,64 @@
 test_ok(f.call([42,55]) == [[42,55]])
 test_ok(f.call(42,55) == [42,55])

+f = lambda { |a, b=42, *c| [a,b,c] }
+test_ok(f.call(1      ) == [1,42,[  ]] )
+test_ok(f.call(1,43   ) == [1,43,[  ]] )
+test_ok(f.call(1,43,44) == [1,43,[44]] )
+
+f = lambda { |a, b=(a|16), *c, &block| [a,b,c,block&&block[]] }
+test_ok(f.call(8      )     == [8,24,[  ],nil] )
+test_ok(f.call(8,43   )     == [8,43,[  ],nil] )
+test_ok(f.call(8,43,44)     == [8,43,[44],nil] )
+test_ok(f.call(8      ){45} == [8,24,[  ],45 ] )
+test_ok(f.call(8,43   ){45} == [8,43,[  ],45 ] )
+test_ok(f.call(8,43,44){45} == [8,43,[44],45 ] )
+
+f = lambda { |a, b=42, *c, d| [a,b,c,d] }
+test_ok(f.call(1      ,99) == [1,42,[  ],99] )
+test_ok(f.call(1,43   ,99) == [1,43,[  ],99] )
+test_ok(f.call(1,43,44,99) == [1,43,[44],99] )
+
+f = lambda { |a, b=(a|16), &block| [a,b,block&&block[]] }
+test_ok(f.call(8   )     == [8,24,nil] )
+test_ok(f.call(8,43)     == [8,43,nil] )
+test_ok(f.call(8,43)     == [8,43,nil] )
+test_ok(f.call(8   ){45} == [8,24,45 ] )
+test_ok(f.call(8,43){45} == [8,43,45 ] )
+test_ok(f.call(8,43){45} == [8,43,45 ] )
+
+f = lambda { |a, b=42, d| [a,b,d] }
+test_ok(f.call(1   ,99) == [1,42,99] )
+test_ok(f.call(1,43,99) == [1,43,99] )
+test_ok(f.call(1,43,99) == [1,43,99] )
+
+f = lambda { |b=42, *c, &block| [b,c,block&&block[]] }
+test_ok(f.call(     )     == [42,[  ],nil] )
+test_ok(f.call(43   )     == [43,[  ],nil] )
+test_ok(f.call(43,44)     == [43,[44],nil] )
+test_ok(f.call(     ){45} == [42,[  ],45 ] )
+test_ok(f.call(43   ){45} == [43,[  ],45 ] )
+test_ok(f.call(43,44){45} == [43,[44],45 ] )
+
+f = lambda { |b=42, *c, d| [b,c,d] }
+test_ok(f.call(      99) == [42,[  ],99] )
+test_ok(f.call(43   ,99) == [43,[  ],99] )
+test_ok(f.call(43,44,99) == [43,[44],99] )
+
+f = lambda { |b=42, &block| [b,block&&block[]] }
+test_ok(f.call(  )     == [42,nil] )
+test_ok(f.call(43)     == [43,nil] )
+test_ok(f.call(43)     == [43,nil] )
+test_ok(f.call(  ){45} == [42,45 ] )
+test_ok(f.call(43){45} == [43,45 ] )
+test_ok(f.call(43){45} == [43,45 ] )
+
+f = lambda { |b=42, d| [b,d] }
+test_ok(f.call(   99) == [42,99] )
+test_ok(f.call(43,99) == [43,99] )
+test_ok(f.call(43,99) == [43,99] )
+
+
 a,=*[1]
 test_ok(a == 1)
 a,=*[[1]]
Index: parse.y
===================================================================
--- parse.y    (revision 16568)
+++ parse.y    (working copy)
@@ -666,6 +666,7 @@
 %type <node> open_args paren_args opt_paren_args
 %type <node> command_args aref_args opt_block_arg block_arg var_ref var_lhs
 %type <node> mrhs superclass block_call block_command
+%type <node> f_block_optarg f_block_opt
 %type <node> f_arglist f_args f_arg f_arg_item f_optarg f_marg f_marg_list
f_margs
 %type <node> assoc_list assocs assoc undef_list backref string_dvar for_var
 %type <node> block_param opt_block_param block_param_def f_opt
@@ -3169,9 +3170,41 @@
             }
         ;

-block_param    : f_arg ',' f_rest_arg opt_f_block_arg
+block_param    : f_arg ',' f_block_optarg ',' f_rest_arg opt_f_block_arg
             {
             /*%%%*/
+            $$ = new_args($1, $3, $5, 0, $6);
+            /*%
+            $$ = params_new($1, $3, $5, Qnil, escape_Qundef($6));
+            %*/
+            }
+        | f_arg ',' f_block_optarg ',' f_rest_arg ',' f_arg opt_f_block_arg
+            {
+            /*%%%*/
+            $$ = new_args($1, $3, $5, $7, $8);
+            /*%
+            $$ = params_new($1, $3, $5, $7, escape_Qundef($8));
+            %*/
+            }
+        | f_arg ',' f_block_optarg opt_f_block_arg
+            {
+            /*%%%*/
+            $$ = new_args($1, $3, 0, 0, $4);
+            /*%
+            $$ = params_new($1, $3, Qnil, Qnil, escape_Qundef($4));
+            %*/
+            }
+        | f_arg ',' f_block_optarg ',' f_arg opt_f_block_arg
+            {
+            /*%%%*/
+            $$ = new_args($1, $3, 0, $5, $6);
+            /*%
+            $$ = params_new($1, $3, Qnil, $5, escape_Qundef($6));
+            %*/
+            }
+                | f_arg ',' f_rest_arg opt_f_block_arg
+            {
+            /*%%%*/
             $$ = new_args($1, 0, $3, 0, $4);
             /*%
             $$ = params_new($1, Qnil, $3, Qnil, escape_Qundef($4));
@@ -3202,6 +3235,38 @@
             $$ = params_new($1, Qnil,Qnil, Qnil, escape_Qundef($2));
             %*/
             }
+        | f_block_optarg ',' f_rest_arg opt_f_block_arg
+            {
+            /*%%%*/
+            $$ = new_args(0, $1, $3, 0, $4);
+            /*%
+            $$ = params_new(Qnil, $1, $3, Qnil, escape_Qundef($4));
+            %*/
+            }
+        | f_block_optarg ',' f_rest_arg ',' f_arg opt_f_block_arg
+            {
+            /*%%%*/
+            $$ = new_args(0, $1, $3, $5, $6);
+            /*%
+            $$ = params_new(Qnil, $1, $3, $5, escape_Qundef($6));
+            %*/
+            }
+        | f_block_optarg opt_f_block_arg
+            {
+            /*%%%*/
+            $$ = new_args(0, $1, 0, 0, $2);
+            /*%
+            $$ = params_new(Qnil, $1, Qnil, Qnil,escape_Qundef($2));
+            %*/
+            }
+        | f_block_optarg ',' f_arg opt_f_block_arg
+            {
+            /*%%%*/
+            $$ = new_args(0, $1, 0, $3, $4);
+            /*%
+            $$ = params_new(Qnil, $1, Qnil, $3, escape_Qundef($4));
+            %*/
+            }
         | f_rest_arg opt_f_block_arg
             {
             /*%%%*/
@@ -4302,6 +4367,44 @@
             }
         ;

+f_block_opt    : tIDENTIFIER '=' primary_value
+            {
+            /*%%%*/
+            if (!is_local_id($1))
+                yyerror("formal argument must be local variable");
+            shadowing_lvar($1);
+            arg_var($1);
+            $$ = NEW_OPT_ARG(0, assignable($1, $3));
+            /*%
+            $$ = rb_assoc_new($1, $3);
+            %*/
+            }
+        ;
+
+f_block_optarg    : f_block_opt
+            {
+            /*%%%*/
+            $$ = $1;
+            /*%
+            $$ = rb_ary_new3(1, $1);
+            %*/
+            }
+        | f_block_optarg ',' f_block_opt
+            {
+            /*%%%*/
+            NODE *opts = $1;
+
+            while (opts->nd_next) {
+                opts = opts->nd_next;
+            }
+            opts->nd_next = $3;
+            $$ = $1;
+            /*%
+            $$ = rb_ary_push($1, $3);
+            %*/
+            }
+        ;
+
 f_optarg    : f_opt
             {
             /*%%%*/