On Monday, 27 August 2012 at 12:14:30 UTC, Manu wrote:
On 27 August 2012 14:08, Carl Sturtivant <sturtiv...@gmail.com>
wrote:
extern(C) void function( ref const(Vector2) v0, ref
const(Vector2) v1,
ref const(Vector2) v2, ref const(Color) color = Color.white,
BlendMode
blendMode = BlendMode.Disabled ) fillTriangle2D;
If function pointers could be called with fewer than the
prototypical
number of arguments, and the remaining arguments be always
initialized to
their .init defaults, you could perhaps make this sort of
thing work
without the default argument values by using struct defaults.
How would that be deficient?
... no.
Color does not .init == Color.white. You're suggesting I define
a new type,
obscuring the API, every time I want a non-.init default arg?
Also, I think it's correct that functions shouldn't be callable
without
explicit parameters. Default args are carefully selected, and
they are
always opt-in.
'v2' in this case shouldn't be allowed to default to [ NaN, NaN
] if I omit
it.
Yes, I am suggesting that to get the default you want you define
a new (free at runtime) type. You need the D declaration of
whichever C struct anyway, so this is that declaration with a
default added. In a more complex situation aliasing can be used.
For e.g. doubles, you can play a suitable struct game for once
and for all, and use it repeatedly inside the D version of C
structs. And I am suggesting the language definition be changed
to allow calls of function pointers be made with some trailing
arguments omitted.
If default arguments for function pointers are not available,
except for the default defaults (.init), then what of this
proposal?
