Templates and expressions
Frits van Bommel
fvbommel at REMwOVExCAPSs.nl
Sun Feb 25 13:31:27 PST 2007
> I've made a template to have a better (in my mind) format for printing,
> so like writef the template take a tuple of argument as a parameter, it
> works well when the parameter are variable but my problem is that if an
> argument of the template is an expression, there is a compilation time
> Ie putf!(x+y) fails to compile..
And it always will as long as (x+y) is not a compile-time constant,
which is (at least) as long as x and/or y is itself not a compile-time
> If I change the prototype to wrap everything in a string, the problem
> now is that as everything is a string I loose access to the type of the
> parameters, which I use..
> Is-there a way to solve this problem?
Or, if it's an option in your implementation, you could generate code
that passes the arguments as parameters to a template function, using
IFTI to get at the types.
> Meta-programming in D will stay quite limited if you're obliged to wrap
> every expression in a string IMHO..
Only expressions that aren't compile-time constants need to be wrapped
in a string (and ones whose type is not a valid template parameter type).
Walter has been talking about passing expressions as alias parameters
or something like that, so maybe this will change.
: and/or Andrei
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