Re: Let's talk about __call

[Peter Aronoff <telemachus@...>]

Patrick Donnelly <batrick@batbytes.com> wrote:
> For some slightly early "It's Friday" discussion, what do you use the
> __call metamethod for? Discuss your favorite hacks, strange problems
> solved, code golf hole-in-ones, etc.

Here’s one that somebody suggestsed for a module of mine. The module is
named split, and the primary method is also split. So if you require it in
a conventional way, you get this:

	local split = require "split"
	local record = "foo,bar,bizz,buzz"
	local fields = split.split(record)

To avoid the redundancy, he suggested packaging the module this way:

	return setmetatable({
	  split      = split;
	  -- various other methods
	},{
	  __call = function(_, ...)
	  return split(...)
	end
	})

So now a user can require the module as normal, but call split using the
module alone. I didn’t do it at the time—I thought that it was too magic
and unnecessary since it’s easy for a user to assign the method to whatever
short name they like when they require the module.

But now I’m curious: is this pattern common in other Lua modules? I don’t
think I’ve seen it, but perhaps I haven’t seen enough.

Best, P
-- 
We have not been faced with the need to satisfy someone else's
requirements, and for this freedom we are grateful.
    Dennis Ritchie and Ken Thompson, The UNIX Time-Sharing System