On Friday, 22 November 2013 at 23:43:26 UTC, luka8088 wrote:
Yes. I still do. And I think that <[ ... ]> should contain
semantically
valid code. In my opinion, if you wish to be able to write
anything
else, the way to go would be: write it using q{ ... }, parse it
yourself, build a valid D AST yourself, give D AST to the
compiler using
mixin().
Then q{ } or <[ ]> would be very limited. Not even templets need
to contain semantically valid code, as long as it's not
instantiated. Usually the idea with AST macros is to take code
that is not valid (semantically) and create a meaning for it
(make it valid). If it's already valid in the first place why use
AST macros at all? Just use the code as is.
Hmm, it could be useful to only allow semantically valid code and
use macros to add new things to the code. But again, very
limiting.
Currently mixin() only accepts a string that contains a valid D
code.
The AST returned from a macro need to be valid D code as well.
So if you have a custom parser for your DSL you need to
generate a D code
from that DSL and then pass it to the compiler using mixin() in
order
for the compiler to parse it again. Double parsing could be
skipped if
mixin() would accept already built D AST and on the other hand
parsing
DSL and building D AST yourself would allow maximum flexibility.
You can already do that today with string mixins, although you
would need to convert the AST back to a string first.
--
/Jacob Carlborg
