• Namespace (20/20) Mar 05 2014 Is there a way to extract the correct typeinfo of an array if I
• Adam D. Ruppe (12/14) Mar 05 2014 Nope, typeinfos are only stored in runtime on classes. All other
• Namespace (2/17) Mar 05 2014 Ah thank you. :)

"Namespace" <rswhite4 googlemail.com> writes:

Is there a way to extract the correct typeinfo of an array if I 
only have the pointer?

Code:
----
import std.stdio;

struct Foo {
	int i;
}

void foo(void* p) {
     // ???
}

void main() {
     Foo[] fs;
     fs ~= Foo();

     foo(fs.ptr);
}
----

Now that we have only the untyped void*: Is there a way how I can 
extract the right typeinfo? Something to rebuild the correct type 
out of the adress.

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Wednesday, 5 March 2014 at 19:15:12 UTC, Namespace wrote:
 Is there a way to extract the correct typeinfo of an array if I 
 only have the pointer?

Nope, typeinfos are only stored in runtime on classes. All other 
types get it only through the static info.

Consider the following:

char[10] a;

char[] b = a[3..5];// from the middle of it

void* c = b.ptr;


Even if the info was stored with a, the slice would have no idea 
where to find it, so you couldn't get it from the pointer either.


The way druntime does it with void pointers is to pass the 
typeinfo too:

void useArray(void[] a, TypeInfo a_type);

"Namespace" <rswhite4 googlemail.com> writes:

On Wednesday, 5 March 2014 at 19:21:39 UTC, Adam D. Ruppe wrote:
 On Wednesday, 5 March 2014 at 19:15:12 UTC, Namespace wrote:
 Is there a way to extract the correct typeinfo of an array if 
 I only have the pointer?

 Nope, typeinfos are only stored in runtime on classes. All 
 other types get it only through the static info.

 Consider the following:

 char[10] a;

 char[] b = a[3..5];// from the middle of it

 void* c = b.ptr;


 Even if the info was stored with a, the slice would have no 
 idea where to find it, so you couldn't get it from the pointer 
 either.


 The way druntime does it with void pointers is to pass the 
 typeinfo too:

 void useArray(void[] a, TypeInfo a_type);

Ah thank you. :)