Type-Def-ing Python

[brianlum]

Dear Python Community,

I have been trying to research how to type-def python.  I want to
type-def python so that I can use it as a static analyzer to check for
bugs.  I have been going over research on this field and I came upon
Brett Cannon's thesis in which he tweaks the compiler and shows that
type-defing python would not help the compiler achieve a 5% performace
increase.

Brett Cannon, "Localized Type Inference of Atomic Types in Python":
http://www.ocf.berkeley.edu/~bac/thesis.pdf

I was wondering if anyone had his contact information so that I could
might ask him for his source code and try to use type-defing as a
bug-finder.

With thanks,
Brian

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Python "member of" function

[brianlum]

Hi,

I was wondering if anyone knew of a built in Python function that will
check if an item is a member of a list, i.e., if item i is a member of
list l.

I read of a function "in" but I can't seem to get that to work and
finding pages for "python in" does not reveal very many relevant
sources.

Thanks!

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Re: Python "member of" function

[brianlum]

Thanks, I was using "in" incorrectly.  Thanks a lot!

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Obtaining the Python Control Flow Graph

[brianlum]

Hi,

I have been looking for a good way to convert python code into a
control flow graph.

I know of Python functions that will convert an expression into an
abstract syntax tree (i.e. ast = parser.expr('(x+5)*5') then t =
ast.totuple() then t), but I am not sure how to obtain a CFG.

I've gone through the compiler and it has code that converts the AST
into a CFG (described here:
http://www.python.org/doc/peps/pep-0339/#ast-to-cfg-to-bytecode).
Basically, PyAST_Compile() in Python/compile.c coverts the AST to a CFG
and outputs final bytecode from the CFG by calling two functions:
PySymtable_Build() in Python/symtable.c and compiler_mod() in
Python/compile.c. PySymtable_Build() will build a symtable and
compiler_mod() will create the CFG.

PyPy also offers a way to obtain a control flow graph:
http://codespeak.net/pypy/dist/pypy/doc/objspace.html#the-flow-model

I was wondering if anyone had any advice on the best way to obtain a
control flow graph.  I need the control flow graph because I am trying
figure out if there is a way to bound the integer ranges and list
lengths at compile time.

Thank you for your help

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Future Warning with Negative Int

[brianlum]

Hi,

If I try to print a negative integer as a hexadecimal, I get the
following error:
FutureWarning: %u/%o/%x/%X of negative int will return a signed string
in Python 2.4 and up

For example:
>>> print "%X" % -1
__main__:1: FutureWarning: %u/%o/%x/%X of negative int will return a
signed string in Python 2.4 and up


Does that mean that in the future it will say -1 or -?  Also,
how do I suppress this warning?

Thanks,
Brian

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