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Created Aug 10, 2009
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from __future__ import with_statement
from functools import partial
import inspect
def accepts_block(f):
class _accepts_block(object):
#use something like this to handle calls without a with()?
def __call__(self, *args):
self.thefunction = partial(f, *args)
return self
def __enter__(self):
# keep track of all that's already defined BEFORE the `with`
frame = inspect.currentframe(1)
self.mustignore = dict(frame.f_locals)
self.res = []
return self.res
def __exit__(self, exc_type, exc_value, traceback):
frame = inspect.currentframe(1)
# see what's been bound anew in the body of the `with`
interesting = dict()
for n in frame.f_locals:
newf = frame.f_locals[n]
if n not in self.mustignore:
interesting[n] = newf
anf = self.mustignore[n]
if id(newf) != id(anf):
interesting[n] = newf
if interesting:
if len(interesting) > 2:
raise "you are only allowed to define a single function inside this with block"
elif len(interesting) == 1:
block = list(interesting.itervalues())[0]
if not isinstance(block, type(lambda:None)):
raise "you must define a function inside this with block"
elif len(interesting) == 2:
block = None
savename = None
for n,v in interesting.iteritems():
if isinstance(v, type(lambda:None)): block = v
else: savename = n
if not savename or not isinstance(block, type(lambda:None)):
raise "you must define a single function inside this with block"
frame.f_locals[savename] = self.thefunction(block)
return _accepts_block()
if __name__ == "__main__":
def bmap(arr, block):
return map(block, arr)
with bmap([1,2,3]) as zootrope:
def foo(x):
return (float(x) + 1) / 2
print zootrope
def each(iterable, block):
for i in iterable: block(i)
with each(["twelve", "fourteen", "sixteen"]):
def _(x):
print x
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