Mailing List Archive: Python: Dev

locals() different behaviour when tracing?

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anders at 0x63

Oct 8, 2009, 6:43 AM

Post #1 of 3 (770 views)
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locals() different behaviour when tracing?

Is it intentional that locals() returns a copy/snapshot of the local
variables sometimes, and sometimes a reference? Like when enabling
tracing, such as in the code pasted below. The documentation ("Update
and return a dictionary containing the current scope's local
variables.") is pretty unclear.

import sys

def X():
l = locals()
i = "foo"
print "Is 'i' in stored locals()? ", ('i' in l)

print "Running normally"
X()

print "Enabling tracing"
def t(*a):
return t
sys.settrace(t)
X()

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benjamin at python

Oct 8, 2009, 7:21 AM

Post #2 of 3 (682 views)
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Re: locals() different behaviour when tracing? [In reply to]

2009/10/8 Anders Waldenborg <anders [at] 0x63>:
>
> Is it intentional that locals() returns a copy/snapshot of the local
> variables sometimes, and sometimes a reference? Like when enabling tracing,
> such as in the code pasted below. The documentation ("Update and return a
> dictionary containing the current scope's local variables.") is pretty
> unclear.

Yes, it does, and that's why the documentation says changing it is undefined. :)

--
Regards,
Benjamin
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solipsis at pitrou

Oct 8, 2009, 8:38 AM

Post #3 of 3 (679 views)
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Re: locals() different behaviour when tracing? [In reply to]

Anders Waldenborg <anders <at> 0x63.nu> writes:
>
> Is it intentional that locals() returns a copy/snapshot of the local
> variables sometimes, and sometimes a reference? Like when enabling
> tracing, such as in the code pasted below.

Since someone else opened a bug, I answered there. Anyone, feel free to correct
me if my answer is wrong.
http://bugs.python.org/issue7083

Regards

Antoine.

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