Why does stringof not like functions with arguments?

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On Wednesday, 9 August 2017 at 01:39:07 UTC, Jason Brady wrote:
> Why does the following code error out with:
>
> app.d(12,10): Error: function app.FunctionWithArguments (uint 
> i) is not callable using argument types ()
>
> Code:
>
> import std.stdio;
>
> void FunctionWithoutArguments() {
> }
>
> void FunctionWithArguments(uint i) {
> }
>
> void main()
> {
> 	writeln(FunctionWithoutArguments.stringof);
> 	writeln(FunctionWithArguments.stringof);
> }

Welcome to optional parentheses hell. Please enjoy your stay.

Because function calls in D can optionally omit the parens, 
`FunctionWithArguments.stringof` is actually attempting to call 
`FunctionWithArguments` without any arguments, and then call 
`stringof` on the result. In other words, it's actually trying to 
do this:

writeln(FunctionWithArguments().stringof);

And the D compiler is rightly telling you that you can't call the 
function with no arguments. The easiest solution is to use 
__traits(identifier) instead:

writeln(__traits(identifier, FunctionWithArguments));

You can make a handy template helper to do this for you:

enum stringOf(alias symbol) = __traits(identifier, symbol);
writeln(stringOf!FunctionWithArguments);