Is there a way to extract code out of a generator function f() into
g() and be able to have f() yield g()'s result without this idiom?:
for g_result in g():
yield g_result
It feels like a clumsy hindrance to refactoring, to have to introduce
a local variable and a loop.
Here is a program that illustrates what I'm trying to achieve--
basically, I want some kind of general mechanism to exhaust one
generator from another.
This was tested on python2.6. The failed attempts all simply produce
the number 50 and stop.
def unfactored():
# toy example, obviously
# pretend this a longer method in need of
# extract-method
yield 50
for num in [100, 200]:
yield num+1
yield num+2
yield num+3
print 'Works fine:'
for x in unfactored():
print x
print
def extracted_submethod(num):
yield num+1
yield num+2
yield num+3
print 'quick test'
for x in extracted_submethod(100):
print x
print
def refactored_original_method():
yield 50
for num in [100, 200]:
# naively delegate
extracted_submethod(num)
# the next does not do what you expect
print 'try naive'
for x in refactored_original_method():
print x
print 'DOH! that is all?'
print
# this feels clumsy
def clumsy_refactored_original_method():
yield 50
for num in [100, 200]:
for x in extracted_submethod(num):
yield x
print 'Works fine:'
for x in clumsy_refactored_original_method():
print x
print
# try to generalize and fail again
def exhaust_subgenerator(g):
for x in g:
yield x
def f():
yield 50
for num in [100, 200]:
exhaust_subgenerator(extracted_submethod(num))
print 'Try again'
for x in f():
print x
print 'DOH! that is all?'
print
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