On Monday, 25 March 2013 at 18:11:54 UTC, J wrote:
On Monday, 25 March 2013 at 16:03:38 UTC, Jacob Carlborg wrote:
On 2013-03-21 19:35, J wrote:
[snip]
I just noticed that Michel Fortin has implemented basic
support for named parameters. I've updated his code to the
latest DMD and pushed it to my fork:
https://github.com/jacob-carlborg/dmd/commit/e363a093040c4b14e7e814027c3e199676c82820
From the commit message:
Add basic support for named parameters.
This will only allow to add the name of the parameter
when calling a function. It doesn't not support passing
the arguments out of order.
All credit goes to Michel Fortin.
+1000
Excellent!
Wow. This is really nice! I added a method to Michel's nice
work. You can get it in this branch.
https://github.com/glycerine/dmd/tree/namedarg
All the dmd test suite then passes.
You can now do this:
void test (double y, double z, int a, int b, int c, string d) { }
void main ()
{
test(y: 33.3,
z: 44.4,
a: 9999,
b: 8888,
7777, // truly optional
d:"Yehaw");
}
I also tested the passing of named parameters through variadic
templates, and there is a little work needed to make them 'named
argument' aware. I added a failing test for that, if anyone wants
to tackle it. It is dmd/test/compilable/namedarg_vararg.d in the
branch above.
$ cat namedarg_vararg.d
cat namedarg_vararg.d
import core.vararg;
import std.stdio;
void test(A...)(A a)
{
foreach(t; a)
writeln(t);
}
void main ()
{
test(x:33.3,
z: 44.4,
a: 9999,
b: 8888,
7777,
d:"Yehaw");
}
$ dmd namedarg_vararg.d
namedarg_vararg.d(12): Error: template
namedarg_vararg.test(A...)(A a) cannot deduce template function
from argument types
!()(x:double,z:double,a:int,b:int,int,d:string)
$
* * *
Wierd and cool: Since the current version requires the exact same
positions as names, it is almost like you get extra refined type
safety for free. Say I have a function that takes two strings.
The compiler can now help me if I mistakenly switch the two...
Example:
void find(string needle, string haystack) { }
void main ()
{
find(haystack: "abcdefg",
needle: "def");
}
dmd can now helpfully point out:
namedarg_haystack.d(6): Error: function namedarg_haystack.find
(string needle, string haystack) is not callable using argument
types (haystack:string,needle:string)
Nice. This has a different feel to it than where the compiler
just 'makes it right' for you, but I still really like it. Super
readable.
