Re: Passing private functions to template algorithms

[Timon Gehr via Digitalmars-d]

On 07.06.2016 20:45, FreeSlave wrote:
I want to bring up this unpleasant topic for discussion, because I'm
really tired of hacks I need to do in my code.
Look at this snippet:

private bool isFileNothrow(string path)
{
     import std.file : isFile;
     import std.exception : collectException;
     bool ok;
     collectException(path.isFile, ok);
     return ok;
}

void main(string[] args)
{
     import std.algorithm : filter;
     auto r = args.filter!(isFileNothrow);
}

Looks good, but it won't compile because isFileNothrow is invisible to
std.algorithm.

Technically it's right: function is private, so no access from other
modules. But it makes me to do hacks like

auto r = args.filter!(p => p.isFileNothrow);

I don't see a way how can I reuse my functions while keeping it private
without ugly hacks.

How about allowing templates from other modules to have access to
private functions? I think this would be pretty legal behavior, since
template is instantiated in this module anyway.

I think it is obvious that this should work. Visibility checks need to 
happen during identifier lookup. This lookup is happening in the module 
where isFileNothrow is visible.