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[Python-Dev] ConfigParser shootout, preliminary entry

Bengt Richter bokr at oz.net
Tue Oct 19 00:06:35 EDT 2004 
On Mon, 18 Oct 2004 21:22:47 -0300, Carlos Ribeiro <carribeiro at gmail.com> wrote:

>On Mon, 18 Oct 2004 22:43:16 GMT, Bengt Richter <bokr at oz.net> wrote:
>> Has anyone discussed using the csv module as the basic file interface for config data?
>
>I believe that CSV files are better suited for regular, table-like
>information, not for the type of data that is normally stored on INI
>files.
Why?

[segment]
sym=something
sam=other

maps trivially to

seg,segment
dat,sym,something
dat,sam,other

etc. E.g.,

 >>> import csv, sys
 >>> for line in csv.reader(sys.stdin): print line
 ...
 seg,segment
 dat,sym,something
 dat,sam,other
 # a comment

 segname
 ,sym,something
 ,sam,somthing
 # might be an alternative
 ^Z
 ['seg', 'segment']
 ['dat', 'sym', 'something']
 ['dat', 'sam', 'other']
 ['# a comment']
 []
 ['segname']
 ['', 'sym', 'something']
 ['', 'sam', 'somthing']
 ['# might be an alternative']

Very easy to deal with.
If you wanted an object with two-level attribute for access like conf.segment.sym, it would
be easy to build, e.g., (admittedly not very robust in this little demo hack ;-)

 >>> import csv, sys
 >>> conf = type('ConfData',(),{})()
 >>> for line in csv.reader(sys.stdin):
 ...     if not line: continue
 ...     if line[0]:
 ...         seg = type('SegData',(),{})()
 ...         setattr(conf, line[0], seg)
 ...         continue
 ...     setattr(seg, line[1], line[2:])
 ...
 segment
 ,sym,sym value
 ,sam,sam value
 seg2
 ,a_float,f,1.0
 ,an_int,i,123
 seg3
 ,msg1,how about this?
 ,msg2,pretty trivial
 ,msg3, ;-)
 ^Z
 ^Z
 >>> vars(conf).keys()
 ['segment', 'seg3', 'seg2']
 >>> vars(conf.segment).keys()
 ['sam', 'sym']
 >>> vars(conf.seg2).keys()
 ['a_float', 'an_int']
 >>> vars(conf.seg3).keys()
 ['msg1', 'msg3', 'msg2']

So we have the hierarchy:

 >>> conf.segment.sam
 ['sam value']
 >>> conf.seg2.an_int
 ['i', '123']
 >>> conf.seg3.msg3
 [' ;-)']

Obviously one could have recognized ['i', '123'] and made conf.seg2.an_int == 123
instead of a list. This is very expandable. E.g., it's not hard to imagine what
    ['img','url=http://www.python.org/pics/pythonHi.gif']
might mean as to how to get and convert such a data spec.

Regards,
Bengt Richter
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