Re: Is there a similar way to do if __name__ == '__main__' as in python ?

[Rici Lake <lua@...>]

On 8-Feb-07, at 1:38 AM, gary ng wrote:

> --- Rici Lake <lua@ricilake.net> wrote:
> > Yes, that's one of the reasons I don't use module().
> >
> > The actual code in my original message avoids
> > hard-coding
> > the module name with the line:
> >
> > local myname = ...
> >
> > at the beginning. That picks up the first argument
> > supplied
> > when the module chunk is called; if it is called by
> > require(),
>
> Ah, I thought module() is now the recommended way.

It is, so take anything I say with a grain of salt.

> But anyway, out of curiosity, what would be the usage
> scenario for not hardcode the module name ? As my
> limited usage of require() is just to load another
> file which is hardcoded in the file system anyway ?

Well, for example, I might want to have two different
versions of a module, say mymodule_v4 and mymodule_v5
both kicking around at the same time.

I can do that by saying:

  local mymodule = require"mymodule_v4"

in any code which wants to use mymodule_v4; there's no global
pollution and the contents of the file mymodule_v4.lua don't
need to know that I've renamed the file.

Of course, most of my code will have:

  local mymodule = require"mymodule"

in it, so I have to make that work, too. I can't use a symlink
because the module system identifies modules names in the package
cache with the filename; however, I can create a file mymodule.lua
with the single line:

  return require"mymodule_v5"

and everything will work nicely.

I could also use a catchall loader which tried to figure
that out for me, perhaps by doing a file listing.