Read files at compile time

[Robert Fraser]

Hi Henrik,

Check out http://www.digitalmars.com/d/expression.html#ImportExpression , which can read files in as compile-time string literals. You'd then need to write a CTFE-compliant string-splitting function and mix that back in. So, you'd have:

mixin(ctfe_split("archetypes", import("file.txt")));

Which should become something like:

char[][3] archetypes = [ "foo", "bar", "baz", ];

Writing the function itself shouldn't be _too_ hard, but there are a number of constructs which make it unable to be executed at compile-time, so ensure it has no side effects.

Regards,
Fraser

Henrik Wrote:

> Hello! 
> 
> I have a question or two regarding what is allowed to be executed at compile time and not. Consider the following:
> 
> <code>
> import std.stdio;
> import std.file;
> import std.string;
> 
> 
> char[][] loadArchetypes( char[] fileName )
> {
>     char[][] archetypes = splitlines( cast(char[])read( fileName ) );
> 
>     return archetypes;
> }
> 
> 
> void main()
> {
>     /// Load archetypes
>     const char[][] archetypes = loadArchetypes( "archetypes.txt" );
> 
>     foreach( archetype; archetypes )
>     {
>         writefln( archetype );
>     }
> }
> 
> </code>
> 
> 
> I suspect that I am not allowed to do this for some reason. I get the very unhelpful error:
> Compiling: fileTest.d
> Error: variable useWfuncs is used before initialization
> Process terminated with status 1 (0 minutes, 0 seconds)
> 0 errors, 0 warnings
> 
> 
> Is it possible to read a file at compile-time in the manner I am trying to do? What does the error message mean?
> 
> 
> Yours most confusedly,
> 
> Henrik