This is a simple recipe which uses generators to execute a chain of functions. These functions and their argurments are internally present in a list.Here use of generators and properties defined on the result set gives more control to users.
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | #!/usr/bin/env python
class chainfunc(list):
def __init__(self):
self.res = []
def append(self, func, *args, **kw):
super(self.__class__, self).append([func,args,kw])
def __call__(self):
for (fn, args, kw) in self:
retval = (fn.__name__, fn(*args, **kw))
self.res.append(retval)
yield retval
def ANDoperation(self):
state = reduce(lambda x,y: x and y, [bool for id,bool in self.res])
return state
and_operation = property(fget=ANDoperation)
def ORoperation(self):
state = reduce(lambda x,y: x or y, [bool for id,bool in self.res])
return state
or_operation = property(fget=ORoperation)
# some sample functions
def t1(name,i):
print name
print i
return True
def t2(id,i=False):
print id
print i
return i
if __name__ == '__main__':
cf = chainfunc()
cf.append(t1,'hello',2)
cf.append(t2,'ab_1',False)
cf.append(t2,'ab_2',True)
gen = cf()
# execute all functions
for i in range(len(cf)):
print "Function name= %s, function State=%s, "%gen.next()
print "AND operation =%s, OR operation=%s\n"%(cf.and_operation, cf.or_operation)
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In the example taken here, there is a group of functions each returning a boolean value. We require different operations to be performed on these functions a) an AND operation of all those return values b) an OR operation of all those return values and results of these define our system. Since the current results of all these functions and their names can be saved in a list, based on manipulation of this result list, various properties can be defined which tell the current status of the system as these functions are executed.
