need design suggestions: local namespace problem

[Ignacio Vazquez-Abrams]

On Tue, 2 Oct 2001, Jason R. Mastaler wrote:

> I'm writing a mail application that needs to have different values for
> variables depending on whether the app is running under qmail or
> Sendmail.
>
> Currently I have those variables in a module called "Defaults.py".
> So, within the program main, I do things like:
>
>   import Defaults
>   sys.exit(Defaults.ERR_HARD)
>
> Some of these variables need to conditionally have different values as
> I mentioned.  For example, exit status codes.  Under qmail,
> `ERR_HARD = 100', while under Sendmail, `ERR_HARD = 75'.
>
> I was thinking of splitting Defaults.py up into multiple files
> (Qmail.py and Sendmail.py), and then using local namespace trickery so
> that within the program main I can do things like:
>
>   if qmail:
>      import Qmail as mta
>   elif sendmail:
>      import Sendmail as mta
>
>   sys.exit(mta.ERR_HARD)
>
> However, the "import module as name" syntax is a Python2-ism, and I'd
> still like to support Python-1.5.2 if I can.

How about this:

sendmail.py
---
class mta:
  ERR_HARD=75
   ...
---

qmail.py
---
class mta:
  ERR_HARD=100
   ...
---

main.py
---
 ...
if issendmail:
  from sendmail import mta
elif isqmail:
  from sendmail import mta
 ...
sys.exit(mta.ERR_HARD)
 ...
---

-- 
Ignacio Vazquez-Abrams  <ignacio at openservices.net>