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"