Re: Type Metatables for Table and Userdata - Powerpatch
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- Subject: Re: Type Metatables for Table and Userdata - Powerpatch
- From: Dirk Laurie <dirk.laurie@...>
- Date: Sun, 9 Dec 2012 19:03:09 +0200
2012年12月9日 John Hind <john.hind@zen.co.uk>:
> Not sure I understand how the latter two suggestions differ, but the first
> certainly requires a constructor function in the global namespace for every
> class which is what I am trying to avoid. My way, the classes occupy their
> own private namespace and even the "class" method is not global existing
> only as a method of Table type.
In Lua 5.2, "the global namespace" is no longer something to be kept tidy
at all costs. You write
do
local A,B,C = A,B,C -- import things from the enclosing environment
local _ENV={} -- global namespace is now empty
-- code that can export only via the imported tables
end
Moreover, one can (in fact, should) put such constructors into
packages. container.list, container.set etc. The C++ STL shows
how it should be done. Sooner or later you need to use something
global. Better IMHO to do it explicitly and visibly rather than
sneaking it in via a subtle property of a newly constructed table.