On Friday, 28 March 2014 at 13:49:59 UTC, Dicebot wrote:
On Friday, 28 March 2014 at 11:59:47 UTC, Colin Grogan wrote:
I'm interested to hear peoples methods for getting around the
lack of foreach loops while using CTFE?
Currently, I've been using a lot of recursive templates, but
its beginning to give me a headache and I'd like to see if
there's better ways around it.
On a related note, is there plans to add foreach support to
CTFE?
Looks like you mix the terminology here. CTFE is "Compile-Time
Function Evaluation" and means exactly that - interpretation of
normal D function during compile-time. Of course, you can use
foreach as usual inside those.
You post implies that you in fact ask about generic
compile-time algorithms over compile-time argument lists, which
is _not_ the same as CTFE. Indeed, lack of static declarative
foreach causes lot of pain during meta-programming.
Relatively common pattern to avoid recursive template horror is
to use private CTFE function inside the template:
template Stuff(T...)
{
private string doStuff()
{
string result;
foreach (Index, Arg; T)
{
// compute value or generate D code
}
return result;
}
enum Stuff = doStuff();
// ..or for complex code-generating things:
mixin(doStuff());
}
Yeah, I am mixing the two up. Not sure what I was thinking
before! Thanks for clarifying.
Im trying to parse command line args and then build a struct that
will, at run-time, hold the data the user passed in via command
line args.
Very similar to Pythons docopt utility ->
https://github.com/docopt/docopt
Up till now, I've been using templates to do all of the work, but
now that I realise I can do it all with functions I might try
that. Then use a mixin template to create the struct with
whatever data is required.
Thanks.
I'm sure I'll be back to bombard ye with questions soon!