Why do this?

Matthew Warren Matthew.Warren at Digica.com
Thu Oct 5 14:34:03 CEST 2006


> [Matthew Warren]
> 
> | Blame outlook and AutoCaps. If number were a number I would write
> | 
> | print "There are",number,"ways to skin a "+furryanimal
> 
> You see now that strikes me as a bit mixed up. Why not simply use?
> 
> print "a", number, "c", string
> 

Habit (not always a good thing..), and it helps keep the distinction as
to what is a number and what is s a string.


> 
> Ultimately it's down to you, but I think you may be doing
> your code a disservice by so assiduously avoiding the %s-style
> of string building. Your last example suggests that you
> see the dict-subtitution flavour simply as an alternative to doing
> "a" + dict[key1] + "b" + dict[key2] etc. I doubt if I've *ever* 
> started with the one and ended with the other; rather I've seen that
> my code would be more readable if I put/had what I wanted into a
> dict (or a dict-like object; just has to support __getitem__).


Not quite. I was meaning that where I had things naturally in a dict and
found myself concatenating the string, I would now probably use the
substitution method.


> 
> An easy example of this is where -- like many, I believe -- I 
> prefer my
> database rows to come in dict-like objects, rather than the 
> tuples which
> the dbapi stipulates. Again, like many, I've used or rolled my own
> wrapper
> which means I can do things like this, where my dbutils.fetch function
> returns some kind of object which traps __getitem__ calls for column
> names and returns the appropriate entry in the underlying tuple:
> 
> <fake code>
> import dbutils
> db = db_module.connect (...)
> for row in dbutils.fetch (db, "SELECT * FROM blah"):
>   print "Customer %(name)s (%(id)d) has %(n_orders)d 
> outstanding orders
> since %(last_order_date)s" % row
> 
> </fake code>
> 
> TJG

I'm only just really looking into the effects of using things like
__getitem__ etc.., I imagine my approach will become more sophisticated
once I have looked into them.


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