Gnarlodious wrote:
Initializing a list of objects with one value:
class Order:
def __init__(self, ratio):
self.ratio=ratio
def __call__(self):
return self.ratio
ratio=[1, 2, 3, 4, 5]
Orders=[Order(x) for x in ratio]
But now I want to __init__ with 3 values:
class Order:
def __init__(self, ratio, bias, locus):
self.ratio=ratio
self.bias=bias
self.locus=locus
def __call__(self):
return self.ratio, self.bias, self.locus
ratio=[1, 2, 3, 4, 5]
bias=[True, False, True, False, True]
locus=['A', 'B', 'C', 'D', 'E']
Orders=[Order(x,y,z) for x,y,z in [ratio, bias, locus]]
ValueError: too many values to unpack (expected 3)
How to do it?
-- Gnarlie
I'm a little off topic but you may want to avoid having inconsistent
interfaces for your class methods, especially when it comes to special
methods like __init__ and __call__.
Having __call__ return a tuple with different length depending on the
initialization of the object is a bad idea. You will surely end up in
unpacking error in the future.
Same things for your attributes, the presence of bias is conditioned by
the object creation... Very bad idea :o)
o1 = Order([1,2,3])
o2 = Order([1,2,3], [4, 5, 6, [7, 8, 9])
print o1.bias
> Unknown attribute
ratio, bias, locus = o2.call()
ratio, bias, locus = o1.call()
> Unpacking error
You could do the following :
class Order:
def __init__(self, ratio, bias=None, locus=None):
self.ratio=ratio
self.bias=bias
self.locus=locus
def __call__(self):
return self.ratio, self.bias, self.locus
It would allow you to create your object with just the ratio and keep a
consistent interface. Unpacking the __call__ return will never fail, and
if you're interested in keeping only ratios, then you can write
ratio, _, _ = o1.call()
JM
PS : accessing attributes using the __call__ method sounds like a little
bit of magic for the lazy guy :o) People expect something to be executed
when calling an object, not getting its attributes. It would be better
to stick with the classic way : o1.ratio
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