Re: bug in os.system?

[nicksjacobson]

OK, I give up.  Why does workaround #2 work?

Also, I didn't realize this before, but when you call os.spawnv, the
argument list you pass starts with the name of the executable you're
calling!  When you call a program from cmd.exe, that program name is
the first parameter automatically.  But with spawnv, you do that
manually!

Anyway, thanks for your help!

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bug in os.system?

[nicksjacobson]

The following code fails (pythonbugtest.exe takes one parameter, a
string):

import os
result = os.system('"pythonbugtest.exe" "test"')
assert(result == 0)

The error message is:

'pythonbugtest.exe" "test' is not recognized as an internal or external
command, operable program or batch file.
Traceback (most recent call last):
  File "C:\Nick\!My Programs\Python\bugtest\python1.py", line 8, in ?
assert(result == 0)
AssertionError


If I remove the quote marks around "pythonbugtest.exe" or "test", it
works fine.  But sometimes I need those quote marks, if e.g. there are
spaces in filenames.

I think this is a bug?

I'm running Python 2.4.1 on Windows XP Pro.

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deprecation of has_key?

[nicksjacobson]

I haven't heard of any plans to deprecate the dictionary has_key
method, as the "in" keyword makes it obsolete.

i.e.
if key in dict:

instead of
if dict.has_key():


Is there some reason to keep has_key?

--Nick

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number conversion

[nicksjacobson]

I'm writing a program to read in raw data from a WAV file, and write it
to an IT file.  I got this to work in C by reading the data into an
array of unsigned chars called "RawDataAry", then converted it to
signed chars by doing the following:

signed char *CharAry = malloc(sizeof(signed char) * frames);
for (i = 0; i < input_frames; i++)
CharAry[i] = (signed char)(((signed short)WavDataAry[i]) - 128);

It worked.


But when I tried to do this kind of conversion in Python, I got an
OverflowError exception.

First I read the data into an array of unsigned chars:

fmt = str(chunklen) + 'B'
fmtsize = struct.calcsize(fmt)
rawdata = struct.unpack(fmt, s[:fmtsize])
rawdata = list(rawdata)

Then I tried to convert it:

charary = array.array('b')
charary.fromlist(rawdata)

This last line threw the OverflowError exception, "OverflowError:
signed char is greater than maximum."

Is there a way to do this??  Thanks a lot in advance!!

--Nick

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