dprop 0.42

Everything is connected, maan!

dprop

Everything is connected, maan!

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This tiny package implements the notion of "dependent properties", whose values are computed based on other properties and cached for re-use, but then smartly invalidated when a (great-)*(grand)?parent property's value changes.

Here is a simple example:

from dprop import independent, depends_on    

class Class:
    a = independent(float)  # type info optional

    @depends_on(a)
    def b(self):
        print('computing b')
        return 6 * self.a

    def __init__(self, a: float):
        # independent properties can be set inside and outside the class as usual
        self.a = a


inst = Class(7)
assert inst.a == 7
assert inst.b == 42  # prints "computing b"

assert inst.b == 42  # value is re-used! (nothing printed)


# Re-setting an independent property invalidates (does not actually delete,
# though) all "later" properties.
inst.a = 26/6
assert inst.b == 26  # prints "computing b"