Is it better to extend a class, or do something repetitious in the main part of a program?

Vinay Sajip vinay_sajip at yahoo.co.uk
Wed Apr 21 10:34:46 CEST 2010


On Apr 19, 3:45 pm, J <dreadpiratej... at gmail.com> wrote:
> First, before I get farther,
>
> Is there a way for theloggingmodule to natively handle lists and
> dict objects whenlogging?
>
> e.g. take this {'key1':'val1','key2':'val2'} and have it logged like this:
>
> INFO: key1: val1
> INFO: key2: val2
>
> If I pass the dict or list directly to the logger, it is logged the
> same as if you simply did this:
>
> mydict={1:1, 2:2}
> mylist=[1,2,3]
>
> print mydict
> print mylist
>
> >>> {1:1,2:2}
> >>> [1,2,3]
>
> It came up that I wanted to haveloggingpresent command line options
> from optparse if the log level was set to debug...  so they'd look
> something like this in the output:
>
> debug: True
> sleep_time: 30
> log_file: /tmp/testlog
>
> So the options I've managed to work out are to either parse the list
> or dict object item by item and feed those items one at a time into
> the logger:
>
> for i in mylist:
>    logging.info(i)
>
> Or to extend the StreamHandler class to handle this by creating a new
> report.msg...
>
> Then the discussion came up: which is better?  To parse a dictionary
> or list in the main code and pass each item to the logger one at a
> time, or to extend the logger to handle it natively?
>
> Any thoughts on which is the more proper way to handle cases like this?

Since you want to have a specific output format for the logged
information, the best way to go would be to write your own Formatter
subclass, and check in its format() method whether you have lists/
dicts and then format them however you want into a string, and return
the appropriately formatted string from that method.

Regards,

Vinay Sajip



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