Chris Rebert wrote:
On Tue, Apr 20, 2010 at 2:59 PM, Alan Harris-Reid
<aharrisr...@googlemail.com> wrote:
Stefan Behnel wrote:
Alan Harris-Reid, 20.04.2010 15:43:
During my Python (3.1) programming I often find myself having to repeat
code such as...
class1.attr1 = 1
class1.attr2 = 2
class1.attr3 = 3
class1.attr4 = 4
etc.
Is there any way to achieve the same result without having to repeat the
class1 prefix? Before Python my previous main language was Visual
Foxpro, which had the syntax...
with class1
.attr1 = 1
.attr2 = 2
.attr3 = 3
.attr4 = 4
etc.
endwith
Is there any equivalent to this in Python?
There's more than one way to do this, depending on your actual needs and
the source of the attributes. I assume this is done in __init__?
This might work for you:
self.__dict__.update(attr1=1, attr2=2, attr3=3, attr4=4)
You should also think once more about the use of the code you presented
above, having to set all those attributes may have a little smell. Maybe
that's totally ok, but since you mention that you "often" find yourself
doing the above, you may also have a mental design problem somewhere. We
can't tell unless you provide a more concrete example than what you show
above.
Stefan
Hi Stefan, thanks for the reply.
The code is not usually in class.__init__ (otherwise I would have used the
self. prefix), but I like your self.__dict__.update(...) solution and I'll
try and remember it.
The code I was thinking of goes something like as follows (don't have a
specific example to hand, but the principal is the same)...
NewClass = BaseClass()
NewClass.attr1 = value1
NewClass.attr2 = value2
NewClass.attr3 = value3
etc.
So if there are more than a couple of attributes to set for a class
instance, how would you approach it (short of passing the values as
parameters to BaseClass)?
Why are you against passing them as parameters?
If your constructor would have a lot of parameters, it may be a sign that:
(A) you have some Data Clumps
(http://martinfowler.com/bliki/DataClump.html) among the parameters
that ought to be made into full objects
(B) your class is doing too many things and needs to be split into
multiple classes
(http://www.refactoring.com/catalog/extractClass.html)
Cheers,
Chris
--
Yay Refactoring!
http://blog.rebertia.com
Hi Chris, thanks for the reply.
Nothing against passing the values as parameters, but it can start to
look a bit ugly if there are too many of them. Which brings me to your
2nd point of maybe refactoring the passing/receiving of parameters so
that I can use an object with attributes instead of individual variable
values.
Thanks,
Alan
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