On Thursday, 21 June 2012 at 19:04:32 UTC, Philippe Sigaud wrote:
On Tue, Jun 19, 2012 at 2:52 PM, Artur Skawina
But, just to be able to say "Real Programmers don't use
mixins": :)
I find Bearophile version quite nice. I did something
equivalent a few
years ago, with string mixins also. […]
Using string mixins as done here isn't just no »real
programmers« thing to do, it has very substantial problems.
The problem with bearophile's code is that it uses T.stringof to
refer to the parameter, but in the real world – where the
template is not defined in the same module as it is used from –
this will not work, as the (non-builtin) argument types will
simply not be in scope (the implementation couldn't possibly
import all the modules the user could ever want to use types
from, even ignoring Voldemort types and the likes for the moment).
I see this mistake – __traits(identifier, …) has just the
same problem, by the way – being made so frequently even by
experienced D programmers (IIRC dranges contains a few instances
of it as well) that I wonder if there is anything we could do
about it design-wise. At least, adding a big warning on how to
_not_ use stringof/__traits(identifier, …) to the language docs
seems like a good idea to me.
Coming back to this particular case, the issue is very easy to
fix: just emit ParameterTypeTuple!F[i] instead of T.stringof from
the mixin generating code.
As far as ref is concerned, I'm not aware of a universal way to
handle it in the general case – I usually end up manually
looking ref-ness up to generate code accordingly (see
ParameterStorageClassTuple).
David
