• BCS (11/11) Jul 24 2007 If you can compile a program with CTFE then you can compile and run a D ...
• Jarrett Billingsley (14/18) Jul 24 2007 How on earth would you do:
• BCS (16/39) Jul 24 2007 I can be done as long as the mixin is global (can != should)

BCS <ao pathlink.com> writes:

If you can compile a program with CTFE then you can compile and run a D program.
If you can do that then you can run the same code and  have it generate .d 
file and then compile that on the next pass.

CTFE for data generation isn't mush harder to work with.

All I'm seeing is that CTFE lets you do it all in one pass (or with bud and 
no "fun stuff")

a script, makefile or whatever should be used for anything of any complexity 
so forgetting to do something isn't much of a problem.

So what does CTFE get you?

I'm wondering if anyone has some examples of where CTFE is a big plus over 
the other options.

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"BCS" <ao pathlink.com> wrote in message 
news:ce0a3343c2708c99c0f56ecb9e4 news.digitalmars.com...
 If you can compile a program with CTFE then you can compile and run a D 
 program.
 If you can do that then you can run the same code and  have it generate .d 
 file and then compile that on the next pass.

How on earth would you do:

mixin(GenCode!(int)("x"));

char[] GenCode(T)(char[] name)
{
    return T.stringof ~ " " ~ name ~ ";";
}

Across the program execution boundary?  How do you pass that template param? 
Your CodeGen program can only take char[][], remember.

(This is a simple example which could be done with templates too, but 
imagine this function is much longer.)

Multiple compilations sounds like a terrible hack, and isn't nearly as 
simple or expressive as this. 

BCS <ao pathlink.com> writes:

Reply to Jarrett,

 "BCS" <ao pathlink.com> wrote in message
 news:ce0a3343c2708c99c0f56ecb9e4 news.digitalmars.com...
 
 If you can compile a program with CTFE then you can compile and run a
 D
 program.
 If you can do that then you can run the same code and  have it
 generate .d
 file and then compile that on the next pass.

 How on earth would you do:
 
 mixin(GenCode!(int)("x"));
 
 char[] GenCode(T)(char[] name)
 {
 return T.stringof ~ " " ~ name ~ ";";
 }

I can be done as long as the mixin is global (can != should)

Your point can also be used for things like BLADE ware lots of semantic stuff 
gets built up and then used. (If inlining could be counted on then this might 
even be done externally)

 Across the program execution boundary?  How do you pass that template
 param? Your CodeGen program can only take char[][], remember.

that char[][] can include file names to input files that can be binary and 
or text. The program can also take as stdin the output from a full build 
(including link errors) and from this learn what is needed.

(again can != should, can ~ should not)

So the benefit of CTFE here is that CTFs can take semantic entities as template 
parameters?

 
 Multiple compilations sounds like a terrible hack, and isn't nearly as
 simple or expressive as this.
 

it's not much worse than lex/yacc. OTOH I'm trying to replace yacc with
templates 
so what can I say?

I guess I was stuck thinking about just functions and then things more like 
yacc.

Thanks for the thoughts. It's exactly what I was hoping for.