• "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> May 06 2009
• Robert Fraser <fraserofthenight gmail.com> May 06 2009
• bearophile <bearophileHUGS lycos.com> May 06 2009
• "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> May 06 2009

"Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:

How can one, in D2, at compile time, convert an integer value (or any 
other type, for that matter) to a string? Here's a simplified example of 
what I want to do:

     import std.conv;

     template Say(int N)
     {
         pragma(msg, to!string(N));
     }

     mixin Say!(123);

This doesn't compile, because the to!string() function for some reason 
can't be evaluated at compile time. (I've included the error messages 
below.)

In D1 I used to write N.stringof, which worked as expected, but in D2 
this would just print "N" instead of "123".

-Lars


Compile errors:
/usr/local/include/d/druntime/core/memory.di(162): Error: cannot 
evaluate gc_malloc(sz,ba) at compile time
/usr/local/include/d/phobos2/std/conv.d(2402): Error: cannot evaluate 
malloc(12u,2u) at compile time
/usr/local/include/d/phobos2/std/conv.d(2454): Error: cannot evaluate 
to(cast(uint)value) at compile time
tmp.d(5): Error: cannot evaluate to(123) at compile time
tmp.d(5): Error: pragma msg string expected for message, not 'to(123)'

tmp.d(8): Error: mixin tmp.Say!(123) error instantiating

Robert Fraser <fraserofthenight gmail.com> writes:

Lars T. Kyllingstad wrote:
 How can one, in D2, at compile time, convert an integer value (or any 
 other type, for that matter) to a string? Here's a simplified example of 
 what I want to do:
 
     import std.conv;
 
     template Say(int N)
     {
         pragma(msg, to!string(N));
     }
 
     mixin Say!(123);
 
 This doesn't compile, because the to!string() function for some reason 
 can't be evaluated at compile time. (I've included the error messages 
 below.)
 
 In D1 I used to write N.stringof, which worked as expected, but in D2 
 this would just print "N" instead of "123".
 
 -Lars
 
 
 Compile errors:
 /usr/local/include/d/druntime/core/memory.di(162): Error: cannot 
 evaluate gc_malloc(sz,ba) at compile time
 /usr/local/include/d/phobos2/std/conv.d(2402): Error: cannot evaluate 
 malloc(12u,2u) at compile time
 /usr/local/include/d/phobos2/std/conv.d(2454): Error: cannot evaluate 
 to(cast(uint)value) at compile time
 tmp.d(5): Error: cannot evaluate to(123) at compile time
 tmp.d(5): Error: pragma msg string expected for message, not 'to(123)'
 
 tmp.d(8): Error: mixin tmp.Say!(123) error instantiating


public template Digit(uint n)
{
	public static const char[] Digit = "0123456789"[n .. n+1];
}

public template Itoa(uint n)
{
	static if(n < 0)
		public static const char[] Itoa = "-" ~ Itoa!(-n);
	else static if (n < 10)
		public static const char[] Itoa = Digit!(n);
	else
		public static const char[] Itoa = Itoa!(n / 10) ~ Digit!(n % 10);
}

template Say(int N)
{
	pragma(msg, Itoa!(N));
}

In D2, replace "const" with "enum" in those declarations if you don't 
want storage allocated for the intermediate results.

bearophile <bearophileHUGS lycos.com> writes:

Lars T. Kyllingstad:
 How can one, in D2, at compile time, convert an integer value (or any 
 other type, for that matter) to a string?


std.metastrings.ToString or std.metastrings.Format, but in D2 that Format is
buggy.

Bye,
bearophile

"Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:

bearophile wrote:
 Lars T. Kyllingstad:
 How can one, in D2, at compile time, convert an integer value (or any 
 other type, for that matter) to a string?


 std.metastrings.ToString or std.metastrings.Format, but in D2 that Format is
buggy.
 
 Bye,
 bearophile


Thank you. ToString did the job. :) I'm currently in the process of 
switching to D2, and after having used only D1+Tango before I am still 
learning my way around Phobos.

-Lars