Carl Banks wrote:
What if the object is a string you just read from a file?
How do you dispatch using polymorphism in that case?
This is where I most miss a switch/case statement in Python...I
do lots of text-file processing (cellular provider data), so I
have lots of code (for each provider's individual format) that
looks like
phones = {}
for row in csv.DictReader(file('data.txt', 'rb')):
phonenumber = row['phonenumber']
if phonenumber not in phones:
phones[phonenumber] = Phone(phonenumber)
phone = phones[phonenumber]
rectype = rectype
if rectype == '01':
phone.international += Decimal(row['internationalcost'])
elif rectype == '02':
phone.text_messaging += (
int(row['textmessages sent']) +
int(row['pages received']) +
int(row['textmessages sent']) +
int(row['pages received'])
elif rectype == ...
...
else:
raise WhatTheHeckIsThis()
which would nicely change into something like
switch row['recordtype']:
case '01':
phone.international += Decimal(row['internationalcost'])
// optionally a "break" here depending on
// C/C++/Java/PHP syntax vs. Pascal syntax which
// doesn't have fall-through
case '02':
phone.text_messaging += (
int(row['textmessages sent']) +
int(row['pages received']) +
int(row['textmessages sent']) +
int(row['pages received'])
...
default:
raise WhatTheHeckIsThis()
This doesn't convert well (i.e. compactly) to a
dictionary-dispatch idiom. :(
-tkc
--
http://mail.python.org/mailman/listinfo/python-list
