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

[Denis Koroskin]

On Mon, 03 Nov 2008 04:11:20 +0300, Daniel Ribeiro Maciel  
<daniel.maciel at gmail.com> wrote:

> Denis Koroskin Wrote:
>
>> On Mon, 03 Nov 2008 01:59:56 +0300, Daniel Ribeiro Maciel
>> <daniel.maciel at gmail.com> 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.