Hello,
i am a longtime Reader of this list and this is the first time i a dare to
speak up.
Apology in advance for any noise, silly comments and not posting to
python-ideas ;).
Am 11.09.2012 12:41, schrieb Victor Stinner:
I plan to implement other optimizations like unrolling loop or convert
a loop to a list comprehension, see the TODO file.
Don't hesitate to propose more optimizations if you have some ideas ;-)
Well how about implementing guards like in pypy?
They are not optimizations by themselves but should enable a whole lot of
them.
I am not good at explaining so i've written this short example (python
2.7.3).
I hope it makes clear what i mean.
Thank you for reading
larudwer
#
# Example for implementing an guard
# by freezing global and local dictionary
# it is not an optimization by itself
# but should open the possibility for them.
#
class WorldChangedException(Exception): pass
class WorldShadowedException(Exception): pass
class frozendict(dict):
def __setitem__(self, key, value):
if key in globals():
if self == locals():
raise WorldShadowedException(key)
else:
raise WorldChangedException(key)
def put(string):
print string
g = frozendict({'put': put, 'foo': 2})
l = frozendict({'bar': 'work fast'})
#
# This is just an poor example.
# astoptimizer should be able to generate
# much better code
#
f = compile("""
put( "trying fast path")
put(bar)
put = 27
""", "<astoptimizer>", "exec")
def test():
global put # Workaround for UnboundLocalError
put("trying slow path")
put = 27
#
# Guard: since the world is frozen, nothing can change.
# if the fast path succeeds we take the result, else
# we use the slow path.
#
try:
exec(f, g, l)
except WorldChangedException, e:
print "WorldChangedException Caught", e
test()
except WorldShadowedException, e:
print "WorldShadowedException Caught", e
test()
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