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September 17, 2012
Get identifier of "this"
Hi,

assuming I have following constuct:

public class Bank{
   public enum test()
   {
     return "writeln(\""~__traits(identfier, this)~"\");";
   }
}

public static void main(){
   Bank b = new Bank;
   mixin(b.test());
}

During compile time, following code should be generated:
writeln("b");

Is this possible? For the demo coding I receive the error, that
"this"
has no identifier.

Kind regards
Andre
September 17, 2012
Re: Get identifier of "this"
On 9/17/12, Andre <andre@s-e-a-p.de> wrote:
> Get identifier of "this"

You can't really get that info at runtime, a class object isn't bound
to a name, 'this' has no identifier. Symbols (like variables) have
identifiers, not objects.

> public class Bank{

Unnecessary, declarations are public by default.

>     public enum test()

'enum' has no meaning in a return type. Either it's 'auto' which
infers the return type from the function body, or it's a specific type
like 'string' (or void if no return type).

>     {
>       return "writeln(\""~__traits(identfier, this)~"\");";

typo: identifier, not identfier

>     }
> }
>

> public static void main(){

public and static have no meaning here.

> During compile time, following code should be generated:
> writeln("b");

It's not possible to mixin a string at compile-time from a string
returned from a method of an object which is instantiated at runtime.
If you want the identifier of the variable then you don't have to deal
with the 'this' reference at all, e.g.:

@property string test(alias symb)()
{
   return "writeln(\"" ~ __traits(identifier, symb) ~ "\");";
}

class Bank { }

void main()
{
   Bank b = new Bank;
   mixin(test!b);
}

Your original sample does cause a compiler ICE but I don't know if
it's worth filing since the code was invalid.
September 17, 2012
Re: Get identifier of "this"
On Mon, 17 Sep 2012 14:01:35 -0400, Andrej Mitrovic  
<andrej.mitrovich@gmail.com> wrote:

> Your original sample does cause a compiler ICE but I don't know if
> it's worth filing since the code was invalid.

Please file, ICE should never occur.

-Steve
September 17, 2012
Re: Get identifier of "this"
On 9/17/12, Steven Schveighoffer <schveiguy@yahoo.com> wrote:
> Please file, ICE should never occur.

You're bound to find a small million of these when it comes to typos
in templates. :)
http://d.puremagic.com/issues/show_bug.cgi?id=8679
September 17, 2012
Re: Get identifier of "this"
On Monday, 17 September 2012 at 18:01:02 UTC, Andrej Mitrovic
wrote:
> On 9/17/12, Andre <andre@s-e-a-p.de> wrote:
>> Get identifier of "this"
>
> You can't really get that info at runtime, a class object isn't 
> bound
> to a name, 'this' has no identifier. Symbols (like variables) 
> have
> identifiers, not objects.
...

Hi Andrej,

thanks a lot for the working sample coding,
this helps me.

Kind regards
Andre
September 17, 2012
Re: Get identifier of "this"
On Monday, September 17, 2012 19:43:24 Andre wrote:
> Hi,
> 
> assuming I have following constuct:
> 
> public class Bank{
> public enum test()
> {
> return "writeln(\""~__traits(identfier, this)~"\");";
> }
> }
> 
> public static void main(){
> Bank b = new Bank;
> mixin(b.test());
> }
> 
> During compile time, following code should be generated:
> writeln("b");
> 
> Is this possible? For the demo coding I receive the error, that
> "this"
> has no identifier.

No. It's not possible. __traits is a compile-time construct, and Bank's 
definition knows nothing about any variables of type Bank declared elsewhere. 
Heck, the code for Bank could be compiled months before the code with b in it 
is even written (and then has the code with Bank linked to it when it's 
compiled). So no, it can't know about b, and what you're trying to do won't 
work.

- Jonathan M Davis
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