[OT] Re: general class functions

[Steven Bethard]

bruno modulix <onurb <at> xiludom.gro> writes:
> 
> class Library:
>    [...]
>    def getAll(self, **kwargs):
>      library=Library()
>      for nation in self.list:
>        keep = True
>        for attribute, value in kwargs.items():
>          if not getattr(nation, attribute) == value:
>            keep = false
>            break
>        if keep :
>          library.add(nation)
>      return library

I haven't been watching this thread, but I saw a pattern here that Python allows
a much easier solution to.  The code:

keep = True
for item in lst:
    if test(item):
        keep = False
        break
if keep:
    ...

can generally be rewritten as:

for item in lst:
    if test(item):
        break
else:

For example:

>>> def loop1(lst, test):
... 	keep = True
... 	for item in lst:
... 		if test(item):
... 			keep = False
... 			break
... 	if keep:
... 		print "reached if"
... 		
>>> def loop2(lst, test):
... 	for item in lst:
... 		if test(item):
... 			break
... 	else:
... 		print "reached if"
... 		
>>> loop1(range(10), lambda x: x == 5)
>>> loop1(range(10), lambda x: x == 11)
reached if
>>> loop2(range(10), lambda x: x == 5)
>>> loop2(range(10), lambda x: x == 11)
reached if

Always good to take advantage of a language construct when you can.  =)

Steve