Martin De Kauwe wrote:
Hi,
if one has a set of values which should never step outside certain
bounds (for example if the values were negative then they wouldn't be
physically meaningful) is there a nice way to bounds check? I
potentially have 10 or so values I would like to check at the end of
each iteration. However as the loop is over many years I figured I
probably want to be as optimal as possible with my check. Any
thoughts?
e.g. this is my solution
# module contain data
# e.g. print state.something might produce 4.0
import state as state
def main():
for i in xrange(num_days):
# do stuff
# bounds check at end of iteration
bounds_check(state)
def bounds_check(state):
""" check state values are > 0 """
for attr in dir(state):
if not attr.startswith('__') and getattr(state, attr) < 0.0:
print "Error state values < 0: %s" % (attr)
sys.exit()
if __name__ == "__main__":
sys.exit(main())
thanks
Martin
Don't check for bounds, fix any bug in the code that would set your
values out of bounds and use asserts while debugging.
Otherwise if you really need dynamic checks, it will cost you cpu, for
sure. Howeverver you could for instance override the __setatttr__ of
state object, and call the attribute's associated function.
class State(object):
funcTable = {
'foo': lambda x: x >= 0.0
}
def __init__(self):
self.foo = 0
def __setattr__(self, attribute, value):
if not self.funcTable.get(attribute, lambda x: True)(value):
sys.exit('error out of bound')
return object.__setattr(self, attribute, value)
Untested, however it's just an idea. I'm not even sure that would be
less cpu consuming :D
That way only attributes in functable execute a (cpu consuming ?) test
function, all other attributes will execute 'lambda x: True'.
The check occurs everytime you set an attribute however.
JM
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