[Python-Dev] test_gzip/test_tarfile failure om AMD64 (original) (raw)

Bob Ippolito bob at redivi.com
Tue May 30 19:15:48 CEST 2006

On May 30, 2006, at 2:41 AM, Nick Coghlan wrote:

Bob Ippolito wrote:

On May 29, 2006, at 8:00 PM, Tim Peters wrote:

We certainly don't want to see two deprecation warnings for a single deprecated behavior. I suggest eliminating the "struct integer wrapping" warning, mostly because I had no idea what it meant before reading the comments in struct.c ("wrapping" is used most often in a proxy or delegation context in Python these days). "'B' format requires 0 <= number <= 255" is perfectly clear all by itself. What should it be called instead of wrapping? When it says it's wrapping, it means that it's doing x &= (2 ^ (8 * n)) - 1 to force a number into meeting the expected range. "integer overflow masking" perhaps?

Sounds good enough, I'll go ahead and change the wording to that.

Reducing it to one warning instead of two is kinda difficult. Is it worth the trouble? If there are cases where only one warning or the other triggers, it doesn't seem worth the effort to try and suppress one of them when they both trigger.

It works kinda like this:

def get_ulong(x): ulong_mask = (sys.maxint << 1L) | 1 if is_unsigned and ((unsigned)x) > ulong_mask: x &= ulong_mask warning('integer overflow masking is deprecated') return x

def pack_ubyte(x): x = get_ulong(x) if not (0 <= x <= 255): warning("'B' format requires 0 <= number <= 255") x &= 0xff return chr(x)

Given the implementation, it will warn twice if sizeof(format) <
sizeof(long) AND one of the following:

  1. Negative numbers are given for an unsigned format
  2. Input value is greater than ((sys.maxint << 1) | 1) for an
    unsigned format
  3. Input value is not ((-sys.maxint - 1) <= x <= sys.maxint) for a
    signed format

-bob

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