www.digitalmars.com         C & C++   DMDScript  

digitalmars.D - Templates at runtime

reply Justin <mrjnewt hotmail.com> writes:
I'm trying to instantiate a templated class at runtime and having some trouble.
My thought is that since something like "Collection!(int)" will return a valid
classinfo, I ought to be able to use ClassInfo.find() and then .create:

module test;

import std.stdio;

void main() {

	myClass!(int) c = new myClass!(int)();

	string cName = c.classinfo.name;
	writefln(cName);
	ClassInfo ci = ClassInfo.find(cName);
	assert(ci !is null);                                    // Line 12

	Object o = ci.create();
	assert(o !is null);

}
public class myClass(T) { }

This outputs:
test.myClass!(int).myClass
Error: AssertError Failure test(12)

Is there a way to "find" a classinfo for such a class at runtime?
Feb 12 2009
next sibling parent reply Steve Schveighoffer <schveiguy yahoo.com> writes:
On Thu, 12 Feb 2009 21:51:01 -0500, Justin wrote:


 Is there a way to "find" a classinfo for such a class at runtime?



I can't see anything incorrect about what you are doing.  Certainly the 
source for druntime seems to indicate it should work.

This is probably a compiler bug.

-Steve
Feb 12 2009
parent "Tim M" <a b.com> writes:
On Fri, 13 Feb 2009 17:38:46 +1300, Steve Schveighoffer  
<schveiguy yahoo.com> wrote:


 On Thu, 12 Feb 2009 21:51:01 -0500, Justin wrote:


 Is there a way to "find" a classinfo for such a class at runtime?



 I can't see anything incorrect about what you are doing.  Certainly the
 source for druntime seems to indicate it should work.

 This is probably a compiler bug.

 -Steve




Probably just not even implemented. A lot of features are just planned and  
reserved.
Feb 13 2009
prev sibling next sibling parent reply Christopher Wright <dhasenan gmail.com> writes:
Justin wrote:

 Is there a way to "find" a classinfo for such a class at runtime?



The slow way:

foreach (modul; ModuleInfo)
	foreach (info; modul.localClasses)
		if (info.name == name) return info;
return null;
Feb 13 2009
next sibling parent reply Ary Borenszweig <ary esperanto.org.ar> writes:
Christopher Wright wrote:

 Justin wrote:

 Is there a way to "find" a classinfo for such a class at runtime?



 The slow way:
 
 foreach (modul; ModuleInfo)
     foreach (info; modul.localClasses)
         if (info.name == name) return info;
 return null;



It doesn't work. It seems only top level classes are included in the 
ModuleInfo.localClasses.

---
module main;

import std.moduleinit;
import std.stdio;

class foo {
}

class myClass(T) {
}

myClass!(int) c;

static this() {
	c = new myClass!(int)();
}

void main() {
	foreach(info; ModuleInfo.modules()) {
		if (info.name != "main") continue;
		
		writefln("%s", info.name);
		foreach(lc; info.localClasses) {
			writefln("  %s", lc.name);
		}
	}
}
---

Output:
main
   main.foo
Feb 13 2009
parent Christopher Wright <dhasenan gmail.com> writes:
Ary Borenszweig wrote:

 Christopher Wright wrote:

 Justin wrote:

 Is there a way to "find" a classinfo for such a class at runtime?



 The slow way:

 foreach (modul; ModuleInfo)
     foreach (info; modul.localClasses)
         if (info.name == name) return info;
 return null;



 It doesn't work. It seems only top level classes are included in the 
 ModuleInfo.localClasses.



Hm. That's odd. Not terribly surprising, I admit; D's runtime reflection 
is lacking.
Feb 14 2009
prev sibling parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
"Christopher Wright" wrote

 Justin wrote:

 Is there a way to "find" a classinfo for such a class at runtime?



 The slow way:

 foreach (modul; ModuleInfo)
 foreach (info; modul.localClasses)
 if (info.name == name) return info;
 return null;



If you look at the source for ClassInfo.find, this is exactly what it does. 
So that probably won't work in this case.

-Steve
Feb 13 2009
prev sibling parent "Simen Kjaeraas" <simen.kjaras gmail.com> writes:
On Fri, 13 Feb 2009 03:51:01 +0100, Justin <mrjnewt hotmail.com> wrote:


 I'm trying to instantiate a templated class at runtime and having some  
 trouble. My thought is that since something like "Collection!(int)" will  
 return a valid classinfo, I ought to be able to use ClassInfo.find() and  
 then .create:

 module test;

 import std.stdio;

 void main() {

 	myClass!(int) c = new myClass!(int)();

 	string cName = c.classinfo.name;
 	writefln(cName);
 	ClassInfo ci = ClassInfo.find(cName);
 	assert(ci !is null);                                    // Line 12

 	Object o = ci.create();
 	assert(o !is null);

 }
 public class myClass(T) { }

 This outputs:
 test.myClass!(int).myClass
 Error: AssertError Failure test(12)

 Is there a way to "find" a classinfo for such a class at runtime?



This is already bugzilla'd. http://d.puremagic.com/issues/show_bug.cgi?id=2484

--
Simen
Feb 15 2009