Calling Syntax (no, not UFCS)
Justin Whear via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Mon Aug 3 16:01:50 PDT 2015
On Mon, 03 Aug 2015 22:42:14 +0000, SirNickolas wrote:
> Hello! I'm new in D and it is amazing!
>
> Can you tell me please if it is discouraged or deprecated to call a
> function by just putting its name, without brackets? It's quite unusual
> for me (used C++ and Python before), but I can see this practice even in
> the official Phobos documentation:
>
> ```
> foreach (result; [ 1, 2, 3, 4 ].map!("a + a", "a * a"))
> ...
> ```
>
> The code `.map!("a + a", "a * a")()` also compiles and works as
> expected, of course.
Opinions vary, but I think it's generally idiomatic to omit empty parens
when chaining but otherwise include them. E.g.:
void foo() { ... }
void main()
{
foo; // don't do this
foo(); // do this
// Empty parens in a chain are just noise:
[1,2,3].map!(i => i + 1)()
.reduce!`a+b`()
.writeln();
// This is better
[1,2,3].map!(i => i + 1)
.reduce!`a+b`
.writeln(); // you may or may not want to conclude
with parens
}
One gotcha that still gets me is with sort:
somearray.sort; // calls the builtin property sort left over from D1,
don't use!
somearray.sort(); // calls std.algorithm.sort with default `a<b`
comparator
So:
somearray.map(i => i+1).array.sort().reduce!`a+b`.writeln();
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