In my previous post (http://forum.dlang.org/thread/jcaomfduqeofobculgli@forum.dlang.org) I asked for an array of pointers to different types, as a stack for my own, where I can generate and insert runtime variables.

However, seems like I need to know the type of variable the pointer is pointing to. That is,

double pi = 3.14159;
size_t ptr = cast(ulong)π // so far oky

double pi_2 = *ptr; // this is where things break down

won't work.

What can I do if the type of the variable is not known?

On Sat, Aug 02, 2014 at 08:21:35PM +0000, seany via Digitalmars-d-learn wrote:
> In my previous post (http://forum.dlang.org/thread/jcaomfduqeofobculgli@forum.dlang.org) I asked for an array of pointers to different types, as a stack for my own, where I can generate and insert runtime variables.
> 
> However, seems like I need to know the type of variable the pointer is pointing to. That is,
> 
> double pi = 3.14159;
> size_t ptr = cast(ulong)π // so far oky
> 
> double pi_2 = *ptr; // this is where things break down
> 
> won't work.
> 
> What can I do if the type of the variable is not known?

You can't do anything unless you do runtime type introspection, say via
TypeInfo (i.e., typeid(x)). But for non-classes, typeid doesn't give
very much information either.

Sounds like what you really want is to use a Variant:

	http://dlang.org/phobos/std_variant.html


T

-- 
You are only young once, but you can stay immature indefinitely. -- azephrahel

Am 02.08.2014 22:21, schrieb seany:
> In my previous post
> (http://forum.dlang.org/thread/jcaomfduqeofobculgli@forum.dlang.org) I
> asked for an array of pointers to different types, as a stack for my
> own, where I can generate and insert runtime variables.
>
> However, seems like I need to know the type of variable the pointer is
> pointing to. That is,
>
> double pi = 3.14159;
> size_t ptr = cast(ulong)π // so far oky
>
> double pi_2 = *ptr; // this is where things break down
>
> won't work.
>
> What can I do if the type of the variable is not known?
>

if you really think you have to do this (and not use variants or something): use an appropriate cast,
i.e. double pi_2 = *(cast(double*)ptr);
furthermore: why not use void* instead of size_t?

Cheers,
Daniel

On Saturday, 2 August 2014 at 20:21:37 UTC, seany wrote:
> In my previous post (http://forum.dlang.org/thread/jcaomfduqeofobculgli@forum.dlang.org) I asked for an array of pointers to different types, as a stack for my own, where I can generate and insert runtime variables.
>
> However, seems like I need to know the type of variable the pointer is pointing to. That is,
>
> double pi = 3.14159;
> size_t ptr = cast(ulong)π // so far oky
>
> double pi_2 = *ptr; // this is where things break down
>
> won't work.
>
> What can I do if the type of the variable is not known?

I there is a sort of data structure then you can use a type tuple as a map, used to interpret your pointers. However it relies on the context.