Re: the equivalent of python's "try import <something> except: import fallback" ?

[Rici Lake <lua@...>]

On 16-Feb-07, at 9:29 PM, gary ng wrote:

> Hi,
>
> I am writing a generic module which I want to use in
> slightly different config and want to do the following
> python equivalent :
>
> try
> import "lcrypto"
> md5 = lcrypto.md5
> except:
> import "my_md5"
> md5 = my_md5.md5

What about:

local md5 =  (pcall(require, "lcrypto") and lcrypto
              or require"my_md5" and my_md5)
             .md5

Or, if the modules actually returned themselves (as imho modules 
should):

function prefer(modname)
  local ok, mod = pcall(require, modname)
  return ok and mod
end

local md5 = (prefer"lcrypto" or require"my_md5").md5