On Thursday, 30 November 2023 at 07:21:29 UTC, Dom DiSc wrote:
So, why supporting the (somewhat strange looking) version with
curly backets at all?
It only works in one special place, so is simply overhead to
remember.
Again a superfluous way to do the same - but only under
specific circumstances.
I think a syntax should work either always or never.
The syntax was inherited from C. The 'special place' is called
initialization, and it's special because the target type of the
initializer is known in advance, while normal expression
assignments are analyzed bottom up. Since there is no
`typeof({10, 10})`, struct initializers don't work as expressions.
C99 added Compound literals `(S){.a = 10, .b = 20}`, and with
named arguments you can do the same in D: `S(a: 10, b:20)`, and
since the type name is included, they do work as standalone
expressions.
Walter tried to deprecate the old struct initializer syntax:
https://github.com/dlang/DIPs/blob/master/DIPs/other/DIP1031.md
But it got some resistance, since {} initializers still have an
advantage when you want to define an array of structs, and don't
want to repeat the (potentially long) struct name for every entry.
Also note that even when {} is removed, there are still other
special cases with initialization, for example with arrays:
```D
void main()
{
short[] a = [3: 10]; // ok
a = [3: 10]; // cannot implicitly convert expression `[3:10]`
of type `int[int]` to `short[]`
}
```
