Jeremie Pelletier wrote: > downs wrote: >> Jeremie Pelletier wrote: >>> grauzone wrote: >>>> Andrei Alexandrescu wrote: >>>>> downs wrote: >>>>>> Andrei Alexandrescu wrote: >>>>>>> downs wrote: >>>>>>>> With all the neat template tricks we have in 2.0, and since we're >>>>>>>> widely redefining the syntax anyway, why not deprecate the current >>>>>>>> cast syntax and move it into object.d as a library function? >>>>>>>> >>>>>>>> So instead of cast(Foo) bar; you would say cast!Foo(bar); .. save >>>>>>>> on a >>>>>>>> keyword and demonstrate language power at the same time. >>>>>>>> >>>>>>>> What sez ye? >>>>>>> What would the implementation look like? >>>>>>> >>>>>>> Andrei >>>>>> Unions, and LOTS of static ifs. :) >>>>> Unions won't work for casting class objects and interfaces because >>>>> those do pointer adjustments. I think cast must be a primitive. >>>> When casting interfaces and objects, the primitive cast just calls >>>> into runtime (functions like _d_dynamic_cast etc.). I don't see a >>>> reason why cast implemented as templated function couldn't call those >>>> runtime functions directly. >>>> >>>>> Andrei >>> What about cast(int) or cast(string) and whatnot then? You'd have >>> cast!A(B) for classes and cast(int) for values, that would be backwards. >>> >>> Jeremie >> >> What about cast!int could _not_ be done as a function? > > I don't want to call into functions for simple value casts. If I want > safe casts I use to!int. It may get inlined in release code, but think > of the debug overhead it would generate. > > The current way is great as it is, cast() for straightforward unsafe > casting and to!(T)() for safe casting. This is exactly what makes D > attractive to me, the choice between safe and unsafe alternatives.
What debug overhead? With current casts, all the logic is in the compiler - where you can't get at it. Moving it into the library can only make this better. There is nothing about cast that I can see that requires dedicated compiler assistance. Furthermore, consider it a testcase - if a trivial function like that isn't inlined, _something_ is wrong :)
