[melbourne-pug] mapping strings to class attributes/operators etc.

lemeia lemeia at bigpond.com
Thu Jan 5 14:13:22 CET 2006

Hi all,

I'm a new member so hello everyone. I'm also a very new Python programmer.
I'm really impressed with how quick it was to pick up Python. I've only really explored it as an option once I moved to the Linux platform from Windows. 

There's several things I'd like to do with Python as an all purpose utility language, but right now I would like to ask some advice on something in particular.

I've got a program I use to read in large files of data which I use to create temporary objects and apply various comparisons and criteria against the objects I create and write to different output files and increment various statistic attributes in my application object for later reporting.

The problem is that this isn't a fixed operation at all. It would be much better for these comparisons and actions to be very dynamic and prevent me from constantly changing the code and rerunning it.

I was thinking I would like to develop some sort of mini-query language. Very simplified and fairly specific to the objects I am creating during my run.

Is there a way in Python (using Dictionaries or something) to map strings to attributes, operators, functions etc...

So if I wanted to say 
object: dimensions
condition: height < 8.4 action: writeReject(height) exception: none

then the application would parse it into a statement like:
if dimension.height < 8.4:

In this way, I could save various conditions and even build them into a string of conditions called a criteria system (for example). I could also use the same mechanism to design reports based on alterable (and storable) conditions that the user specifies. 

Can this sort of thing be done cleverly in Python?


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