"Michel Fortin" <michel.for...@michelf.com> wrote in message news:istqjn$2jld$1...@digitalmars.com... > On 2011-06-10 14:52:53 -0400, Robert Clipsham <rob...@octarineparrot.com> > said: > >> On 10/06/2011 19:06, Andrei Alexandrescu wrote: >>> Ugly is in the eye of the beholder, but I fail to see how the added >>> punctuation makes Flag!"param".yes significantly more verbose than param >>> : true. >> >> foo(param: true, otherParam: false); >> foo(Flag!"param".yes, Flag!"otherParam".no); >> >> I don't know about you, but I find the former is far more legible. I'd >> hate to see my code littered with Flag!"something". > > I have to say I totally agree with Robert. > > I agree with the need for a way to name parameters, but instantiating a > pseudo-boolean type from a template for each function parameter is worse > than the initial problem. Templates are already a difficult concept to > grasp for most people (because they're so abstract), we really don't need > to replace every boolean parameter with a template type. > > >>> The problem that named parameters are still optional remains. Or we need >>> to add one extra language feature to specify required named parameters. >> >> void foo(bool param, bool otherParam, bool thisOneIsntRequired = false); >> >> Call it with or without named parameters, two are required, one is not. >> >> foo(otherParam: true, param: false); >> foo(true, false); >> foo(otherParam: true, param: false, thisOneIsntRequired: true); > > And just try to think of the signature for the function above if it was > using Flag! > > void foo(Flag!"param" param, Flag!"otherParam" otherParam, > Flag!"thisOneIsntRequired" thisOneIsntRequired = > Flag!"thisOneIsntRequired".no); > > Do we really want to expose that in the documentation? >
I completely agree with Robert and Michel on all the points they've raised. Flag is admittedly a great example of the power of D's templates. And it's admittedly a very clever hack to get around *some* of the limitations of not having named parameters...*But* it's *still* just that: a hack to get around some of the limitations of not having named parameters. And yes, it is comparatively ugly, as Robert and Michel's examples have very clearly shown. Also: >>> The problem that named parameters are still optional remains. Or we need >>> to add one extra language feature to specify required named parameters. If by that, you meant that the caller is allowed to call the function without naming the parameters, I really don't see that as a problem. Yea, *maybe* it would be better if the callee could optionally decide "caller must use named params", but even without that, it's a hell of a lot better than the current state, and it's also a lot better than Flag becase 1. It's *much* cleaner for both the caller and callee, and 2. It works for functions like foo(int, int, int, int), not just bools.
