From: hanmac@...
Date: 2014-09-08T09:55:45+00:00
Subject: [ruby-core:64855] [ruby-trunk - Feature #10214] new functions for compare of symbols in C API

Issue #10214 has been updated by Hans Mackowiak.


i did some testing with that if someone is interested:

~~~

#include <ruby.h>

VALUE is_dyn(VALUE self)
{
	return DYNAMIC_SYM_P(self) ? Qtrue : Qfalse;
}

VALUE check_symbol(VALUE self)
{
	VALUE str = rb_sym2str(self);
	ID id = rb_intern(StringValueCStr(str));
	return ID2SYM(id) == self ? Qtrue : Qfalse;
}

VALUE check_symbol_is_dyn(VALUE self)
{
	VALUE str = rb_sym2str(self);
	ID id = rb_intern(StringValueCStr(str));
	return DYNAMIC_SYM_P(ID2SYM(id)) ? Qtrue : Qfalse;
}

void Init_symtest()
{
	rb_define_method(rb_cSymbol,"dynamic?",is_dyn,0);
	rb_define_method(rb_cSymbol,"check",check_symbol,0);
	rb_define_method(rb_cSymbol,"check_dyn",check_symbol_is_dyn,0);
};

~~~

~~~
s="xyzed".to_sym #=> :xyzed
s.dynamic? #=> true
s.check #=> true
s.dynamic? #=> true
s.check_dyn #=> true

~~~

hm means that the check does works better than i thought ... hm the only thing i think that might happen is that ID2SYM(rb_intern(chr)) not allways returns a static symbol ... so it might be safer to still store the ID values and make symbols out of them when needed, because currently dont know what worse could happen ...

----------------------------------------
Feature #10214: new functions for compare of symbols in C API
https://bugs.ruby-lang.org/issues/10214#change-48722

* Author: Hans Mackowiak
* Status: Feedback
* Priority: Normal
* Assignee: 
* Category: core
* Target version: 
----------------------------------------
currently i often use Symbols as enums in my bindings, 
have something like this with comparing symbols by their ID

~~~
if(SYMBOL_P(sym))
{
  if(rb_intern("name") == SYM2ID(sym))
    return ENUM_NAME;
}
~~~

now with dynamic symbols and other ones, its problematic because with that i always foce a dynamic symbol to become static or pinned (that what SYM2ID does)

so imo there need to be better ways to comare is an ID and a VALUE-sym or two VALUE-syms and check if they have the same content (hm because comparing two VALUE with == might/does not work) 



-- 
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