On Thu 14 Aug 2008 11:19:06 AM EDT, Larry Bates wrote:
> eliben wrote:
>> Hello,
>>
>> I want to be able to do something like this:
>>
>> Employee = Struct(name, salary)
>>
>> And then:
>>
>> john = Employee('john doe', 34000)
>> print john.salary
I find something like this useful, especially if any time I tried to
cram in an attribute that wasn't allowed, the class raises an exception.
One way to do it is to make a function that defines a class inside and
then returns it. See the code at the end of this post for an example.
I couldn't figure out how to do this part though:
>> Employee = Struct(name, salary)
I have to do this instead (notice that the args are strings):
>> Employee = Struct('name', 'salary')
Anyway, here's the code:
def struct_maker(*args):
class C(object):
arglist = args
def __init__(self, *different_args):
# Catch too few/too many args.
if len(self.arglist) != len(different_args):
raise ValueError("I need exactly %d args (%s)"
% (len(self.arglist), list(self.arglist)))
for a, b in zip(self.arglist, different_args):
setattr(self, a, b)
def __setattr__(self, k, v):
"Prevent any attributes except the first ones."
if k in self.arglist:
object.__setattr__(self, k, v)
else:
raise ValueError("%s ain't in %s"
% (k, list(self.arglist)))
return C
And here it is in action:
In [97]: Employee = struct_maker('name', 'salary')
In [98]: matt = Employee('Matt Wilson', 11000)
In [99]: matt.name, matt.salary
Out[99]: ('Matt Wilson', 11000)
In [100]: matt.invalid_attribute = 99
---------------------------------------------------------------------------
ValueError: invalid_attribute ain't in ['name', 'salary']
Matt
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