Dynamic language

[Adam D. Ruppe]

On Friday, 16 March 2012 at 11:22:07 UTC, Boscop wrote:
> How would it be possible, the type of the delegate can't be 
> typechecked at the call-site, because the type info is lost in 
> the variant.

The trick is to build wrapper functions at the assignment
point, where you still have all the type info.

I showed that with the wrap() template in the implementation
in a previous post - std.traits.ReturnType and
std.traits.ParameterTypeTuple help a lot there.

This same technique can do all kinds of conversions: I
use it to do strings -> calls for web apps and Variant ->
calls for this dynamic thing, weak typing, and script
interaction.

Remember, that while the wrapper is showed at the
assignment type, it is a compile time thing to
build the wrapper, so the assignment is still cheap.

The call has a small runtime hit though, since it does
the type conversions or checks there.

If you wanted strict type checking, it could probably
be fast; Variant.get() has a small cost.