# Tuple assignment and generators?

Diez B. Roggisch deets at nospam.web.de
Thu May 4 18:00:15 CEST 2006

```Tim Chase wrote:

> Just as a pedantic exercise to try and understand Python a
> bit better, I decided to try to make a generator or class
> that would allow me to unpack an arbitrary number of
> calculatible values.  In this case, just zeros (though I
> just to prove whatever ends up working, having a counting
> generator would be nice).  The target syntax would be
> something like

<snip/>

By using this:

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/284742

I came up with a small decorator doing that:

import inspect, dis

def expecting():
"""Return how many values the caller is expecting"""
f = inspect.currentframe()
f = f.f_back.f_back
c = f.f_code
i = f.f_lasti
bytecode = c.co_code
instruction = ord(bytecode[i+3])
if instruction == dis.opmap['UNPACK_SEQUENCE']:
howmany = ord(bytecode[i+4])
return howmany
elif instruction == dis.opmap['POP_TOP']:
return 0
return 1

def variably_unpack(f):
def d(*args, **kwargs):
r = f(*args, **kwargs)
exp = expecting()
if exp < 2:
return exp
return (r.next() for i in xrange(exp))
return d

@variably_unpack
def test():
def gen():
i = 0
while True:
yield i
i += 1
return gen()

a, b, c = test()

print a,b,c

a, b, c, d = test()

print a,b,c, d

Diez

```

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