Ben Hanson wrote:
== Quote from BCS (n...@anon.com)'s article
Hello bearophile,
Ben Hanson:
Can you output source code at compilation time and have D compile it,
or do you use a load of recursion like C++ TMP?
This can be done with string mixin. You can use compile-time
evaluation to build a string of code, and the mix it in somewhere, the
compiler will compile it. It's a dirty thing, but unless D3 gets
macros, it's the thing to be used. You can use it to build a string of
asm code too, because it's part of D syntax.
OTOH, and IHMO it should be avoided where you can, kinda like goto.
(For
one things, forget having usable line numbers in your error messages.)
Whenever that happens, it's a compiler bug.
If you can produce a test case where that happens, please put it in
Bugzilla.
You
can often get a lot done with static if, tuple foreach, const values feed
to boilerplate code and the like with just a scattering of one or two line
mixins stuffed in the middle.
Bye,it.
bearophile
It occurred to me that you could have a normal regex library that builds the
regex at
runtime, debug it, produce a code generator (similar code to re2c), debug that
and then just
wrap it with the mixin at the end. If you run into bugs, you can just do it at
runtime
instead and debug. The nice thing is, if I can get this converted, the lexer
library is just
slightly different. That means you could have the same approach with a lexer
generator! This
would lead to huge interest from the boost.spirit guys...
That is exactly the way I recommend to develop CTFE code. Get the code
completely working, run unit tests on every component, and then CTFE it.
