struct.pack bug?

[Jonathan Fine]

Hello

I find the following inconsistent:
===

>>sys.version

'2.4.1a0 (#2, Feb 9 2005, 12:50:04) \n[GCC 3.3.5 (Debian 1:3.3.5-8)]'

>>pack('>B', 256)

'\x00'

>>pack('<B', 256)

'\x00'

>>pack('B', 256)

Traceback (most recent call last):
File "<stdin>", line 1, in ?
struct.error: ubyte format requires 0<=number<=255

>>>

===

I was hoping that '>B' and '<B' would raise an exception,
ust as 'B' does.


On Oct 27 2006, 11:17 am, Jansson Christer reported a
different anomoly to this newsgroup, using the same
subject.

--
Jonathan

[John Machin]

Re: struct.pack bug?

On Feb 9, 8:58 am, Jonathan Fine <j...@pytex.org wrote:

Hello
>
I find the following inconsistent:
===

>>sys.version

'2.4.1a0 (#2, Feb 9 2005, 12:50:04) \n[GCC 3.3.5 (Debian 1:3.3.5-8)]'

>>pack('>B', 256)

'\x00'

>>pack('<B', 256)

'\x00'

>>pack('B', 256)

Traceback (most recent call last):
File "<stdin>", line 1, in ?
struct.error: ubyte format requires 0<=number<=255

>>>

===
>
I was hoping that '>B' and '<B' would raise an exception,
ust as 'B' does.
>
On Oct 27 2006, 11:17 am, Jansson Christer reported a
different anomoly to this newsgroup, using the same
subject.

Your Python is out-of-date in two dimensions: the 2.4 series is way
past 2.4.1, and Python 2.5 has been out for a while.

Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit
(Intel)] on win
32
| >>from struct import pack
| >>pack('<B', 256)
| __main__:1: DeprecationWarn ing: 'B' format requires 0 <= number <=
255
| '\x00'

Until the deprecation warning becomes an exception in 2.6, I'd suggest
doing your own checking:
assert 0 <= pack_B_candidat e <= 255

HTH,
John