Hello everybody,
I'm designing a container class that supports slicing.
The problem is that I don't really know how to do it.
class MyClass(object):
def __init__(self, input_data):
self._data = transform_input(input_data)
def __getitem__(self, key):
if isinstance(key, slice):
# return a slice of self
pass
else:
# return a scalar value
return self._data[key]
The question is how to return a slice of self.
First I need to create a new instance... but how? I can't
use MyClass(self._data[key]) because the __init__ method
expects a different kind of input data.
Another option is
out = MyClass.__new__(MyClass)
out._data = self._data[key]
return out
But then the __init__ method is not called, which is
undesirable because subclasses of this class might need
to set some custom settings in their __init__ method.
So what is there to do? Any suggestion?
Cheers.
Ernest
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