• Dom DiSc (13/13) May 03 2023 Sometimes I'm unsure what exactly is the difference between
• Dennis (7/14) May 03 2023 No, a cast allows for overflow `cast(ubyte) 256`, while the

Dom DiSc <dominikus scherkl.de> writes:

Sometimes I'm unsure what exactly is the difference between

a)   cast(t)x
b)   (t)x
c)   t(x)

I know, (c) is a constructor call, but for basic types that's the 
same as (a) isn't it?
If t provides a constructor for typeof(x) and x provides opCast 
to type t, which one is called?
Does it depend on the form (a), (b), or (c)?
Does all three forms work if only the constructor or only the 
opCast is provided?
And is (b) always equivalent to (a)? (there is an odd example in 
the grammar where this is not the case)

Dennis <dkorpel gmail.com> writes:

On Wednesday, 3 May 2023 at 09:03:38 UTC, Dom DiSc wrote:
 I know, (c) is a constructor call, but for basic types that's 
 the same as (a) isn't it?

No, a cast allows for overflow `cast(ubyte) 256`, while the 
constructor needs an integer that fits. `ubyte(256)` is an error.

 If t provides a constructor for typeof(x) and x provides opCast 
 to type t, which one is called?

When casting, opCast has precedence over a constructor.

 Does all three forms work if only the constructor or only the 
 opCast is provided?

A constructor call will not be lowered to opCast, but a cast can 
be lowered to a constructor call.

 And is (b) always equivalent to (a)?

C style cast syntax is not allowed in D.