Comment #0 by bearophile_hugs — 2013-01-12T13:46:15Z
This is a spinoff of Issue 5140 , see there for more info and discussions.
Inside a function __function (or __func) is the alias to the function itself. It allows code like this, this recursive code will keep working even if "fact" gets renamed, it's more DRY (http://en.wikipedia.org/wiki/Don%27t_Repeat_Yourself ):
long fact(long n) {
if (n <= 1)
return 1;
else
return n * __function(n - 1);
}
void main() {
assert(fact(20) == 2_432_902_008_176_640_000);
}
See a better explanations and some examples of __function:
http://rosettacode.org/wiki/Anonymous_recursion
It's like the difference between D OOP and Java, this is Java-like code:
class Foo {
Foo(int x) {...}
void bar(Foo f) {
Foo g = new Foo(5);
...
}
}
This is one possible equivalent D code, it contains the name Foo only once:
class Foo {
this(int x) {...}
void bar(typeof(this) f) {
auto g = new typeof(this)(5);
...
}
}
Another use case for __function:
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D.learn&article_id=26404
Comment #1 by b2.temp — 2017-02-26T03:19:28Z
It's easy to do at the library level:
auto recursion(string Fun = __FUNCTION__ , A...)(auto ref A a)
{
import std.typecons: tuple;
mixin("return " ~ Fun ~ "(" ~ a.stringof ~ "[0..$]);");
}
used like this:
long factorial(long a)
{
if (a <= 1)
return a;
else
return a * recursion (a-1);
}
void main()
{
auto a = factorial(20);
}
So maybe this one could be closed as WONTFIX ?
Comment #2 by dlang-bot — 2020-08-09T10:29:14Z
@NilsLankila updated dlang/dmd pull request #11538 "add `__traits(getCurrentFunction)`" fixing this issue:
- fix issue 8109, 9306, add `__traits(getCurrentFunction)`
This new traits is a shortcut allowing to call the function we
are in without using `mixin` and `__FUNCTION__` tricks.
https://github.com/dlang/dmd/pull/11538