Re: How to get a function name (string) @ compile time

[Simen Kjaeraas]

On Mon, 03 Nov 2008 12:33:05 +0100, Denis Koroskin <[EMAIL PROTECTED]>  
wrote:

On Mon, 03 Nov 2008 04:11:20 +0300, Daniel Ribeiro Maciel  
<[EMAIL PROTECTED]> wrote:

Denis Koroskin Wrote:

On Mon, 03 Nov 2008 01:59:56 +0300, Daniel Ribeiro Maciel
<[EMAIL PROTECTED]> wrote:

> How do we get a function name (string) @ compile time?
>
> I need to do stuff like (in C)
>
> #include <stdio.h>
>
> #define HELLO( func ) \
>   printf( "calling " #func "\n" ); \
>   func();
>
> void foo()
> {
>    printf( "@foo" );
> }
>
> int main()
> {
>    HELLO( foo );
>    printf( "\n" );
> }
>
> The output is:
> calling foo
> @foo
>
> Thanks in advance,
> Daniel
>

Just in case you know little D here is the source code, explanation and
comparison to C++:

import std.stdio; // this is used to import writefln() - a function
similar to printf (but typesafe)

// this is a template function that takes almost anything (close to C++
templates and C macros)
void print(alias functionName)()
{
     // stringof is used to take a string representation of the  
identifier
     writefln("Calling ", functionName.stringof);

     // let's invoke it! This will succeed if functionName is a  
function,
pointer to function,
     // delegate or an object that have overloaded opCall() (similar  
to C++
operator())
     functionName();
}

void foo()
{
     writefln("@foo"); // same as printf("@foo);
}

void main()
{
     // foo is a global (free) function. it is passed to the template
function.
     // In C++ you would do print<foo>(); (but C++ doesn't support
specializing
     // templates with functions nor does it have .stringof)
     print!(foo);
}

Thanx a lot! It worked for some functions.

I found a problem though. If we change foo to:

void foo( double i )
{
     writefln("@foo ", i );
}

the compiler yields an error:

test.d(30): function app.sandbox.main.foo (double i) does not match  
parameter types ()
test.d(30): Error: expected 1 arguments, not 0]

line 30 is this:      writefln("Calling ", functionName.stringof);

Is this supposed to be a bug?

Best regards,
Daniel


Yes, it is. For some reason it tries to evaluate function first and  
*then* take the stringof property (that is of the returned value), i.e.  
it rewrites it as "functionName().stringof". I have written about this  
bug 4 months ago ("Omittable parens is an evil" thread) but it is not  
fixed yet.

That's not the only error here. Your template function also calls
foo with no arguments on  the line below that bug. Fixing that would
probably include the ParameterTypeTuple and ReturnType templates.

--
Simen