Alias template param - Undefined Identifier

[anonymous]

On Tuesday, 18 March 2014 at 23:10:05 UTC, Chris Williams wrote:
> Annoying that formatting the string is required. I think you're 
> right that it's ignoring my alias parameter because I'm not 
> using it. Formatting doesn't accomplish anything except to use 
> the parameter. But in exchange, you have to relate your format 
> arguments to the %s entries, instead of the q{} contents just 
> being code.
>
>
> import fs = std.file;
> import std.stdio;
> import std.string: format;
>
> template gotoPath(alias path) {
>     enum gotoPath = format(q{
>         string currPath = fs.getcwd();
>         scope (exit) fs.chdir(currPath);
>         fs.chdir(%s);
>     }, __traits(identifier, path));
> }
>
> void doStuff(string targetDirectory) {
>     mixin(gotoPath!(targetDirectory));
>     writefln("b %s", fs.getcwd());
> }
>
> void main() {
>     writefln("a %s", fs.getcwd());
>     doStuff("/etc");
>     writefln("c %s", fs.getcwd());
> }


I feel like there might be a misunderstanding. It's not that the
parameter was ignored because it wasn't used. You're not giving
the compiler a little extra help.

You're building a string from the parameter. __traits(identifier,
path) isn't "path", it's "targetDirectory" (in this specific
instantiation).