rb_iterate

[Tim Pease]

If anyone out there has used the "rb_iterate" function in a Ruby C
extension, could you please post a simple explanation of (a) how to
use the function and (b) an explanation of the method signature?

From eval.c ...

VALUE
rb_iterate(it_proc, data1, bl_proc, data2)
VALUE (*it_proc) _((VALUE)), (*bl_proc)(ANYARGS);
VALUE data1, data2;
{
...
}


I understand that "it_proc" and "bl_proc" are function pointers and
"data1" and "data2" are the arguments that are passed to each
function, respectively. What I don't understand is how all these work
together to iterate over a collection.

Pointers, tips, tutorials, explanations?

Blessings,
TwP

 

[ara.t.howard]

If anyone out there has used the "rb_iterate" function in a Ruby C
extension, could you please post a simple explanation of (a) how to
use the function and (b) an explanation of the method signature?


VALUE
rb_iterate(it_proc, data1, bl_proc, data2)
VALUE (*it_proc) _((VALUE)), (*bl_proc)(ANYARGS);
VALUE data1, data2;
{
...
}


I understand that "it_proc" and "bl_proc" are function pointers and
"data1" and "data2" are the arguments that are passed to each
function, respectively. What I don't understand is how all these work
together to iterate over a collection.

Pointers, tips, tutorials, explanations?

see ext/dbm/dbm.c


at a glance at this

492 static VALUE
493 fdbm_replace(obj, other)
494 VALUE obj, other;
495 {
496 fdbm_clear(obj);
497 rb_iterate(each_pair, other, update_i, obj);
498 return obj;
499 }

this

463 static VALUE
464 each_pair(obj)
465 VALUE obj;
466 {
467 return rb_funcall(obj, rb_intern("each_pair"), 0, 0);
468 }


this

472 static VALUE
473 update_i(pair, dbm)
474 VALUE pair, dbm;
475 {
476 Check_Type(pair, T_ARRAY);
477 if (RARRAY(pair)->len < 2) {
478 rb_raise(rb_eArgError, "pair must be [key, value]");
479 }
480 fdbm_store(dbm, RARRAY(pair)->ptr[0], RARRAY(pair)->ptr[1]);
481 return Qnil;
482 }


and this

795 rb_define_method(rb_cDBM,"replace", fdbm_replace, 1);


i think we can translate

497 rb_iterate(each_pair, other, update_i, obj);

which would look like

dbm.replace other

in ruby

as

iterate over 'other' via the method 'each_pair' and, for each yielded pair,
call the method 'update_i' on 'obj'.

at least that what i'm guessing - i have __no__ idea ;-)

regards.


-a

 

[George Ogata]

If anyone out there has used the "rb_iterate" function in a Ruby C
extension, could you please post a simple explanation of (a) how to
use the function and (b) an explanation of the method signature?

From README.EXT:

** Control Structure

VALUE rb_iterate(VALUE (*func1)(), void *arg1, VALUE (*func2)(), void *arg2)

Calls the function func1, supplying func2 as the block. func1 will be
called with the argument arg1. func2 receives the value from yield as
the first argument, arg2 as the second argument.

VALUE rb_yield(VALUE val)

Evaluates the block with value val.