On Thu, 4 Dec 2008 12:11:08 -0800 (PST), Roy Smith <[EMAIL PROTECTED]> wrote:
I'm working with marshaling data over a binary wire protocol. I'm
using struct.pack() to handle the low-level encoding of ints. One of
the things I need to do is make sure an int can be represented in 4
bytes. Is there a portable way to do that? For now, I'm doing signed
ints, but I'll certainly have to do unsigned 32-bit ints (and 64-bit
ints) at some point. Not to mention shorts and chars.
At first I thought pack() might raise an exception on a value
overflow, that but doesn't seem to be the case:
[hex(ord(c)) for c in struct.pack('!i', 999999999999999999999L)]
['0xde', '0x9f', '0xff', '0xff']
Should I be thinking more along the lines of bit masking (and worrying
about all the niggling 2-complement issues) in the Python code? Or is
there some cleaner way to do this?
How about simple bounds checking? An integer fits in an unsigned 32bit
representation if it is greater than or equal to 0 and less than 2 ** 32.
The bounds for the sizes are similarly simple to determine and check.
Jean-Paul
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