Can I create class properties during __new__ or __init__?

Question

I want to do something like this, but I haven\'t had much success so far. I would like to make each attr a property that computes _lazy_eval only when accessed:

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Answer 1

Technically you want a metaclass:

class LazyMeta(type):
    def __init__(cls, name, bases, attr):
        super(LazyMeta, cls).__init__(name, bases, attr)
        def prop( x ):
            return property(lambda self: self._lazy_eval(x))
        for x in attr['lazyattrs']:
            setattr(cls, x, prop(x))

class Base(object):
    __metaclass__ = LazyMeta
    lazyattrs = []
    def _lazy_eval(self, attr):
        #Do complex stuff here
        return attr

class Child(Base):
    lazyattrs = ['foo', 'bar']

me = Child()

print me.foo
print me.bar