Gregory P. Smith schrieb:

The documentation for the struct module says:

http://docs.python.org/dev/library/struct.html#module-struct

"short is 2 bytes; int and long are 4 bytes; long long (__int64 on Windows) is 8 bytes"

and lists 'l' and 'L' as the pack code for a C long.

As its implemented today, the documentation is incorrect. On an LP64 host (pretty much any 64-bit linux, bsd or unixish thing) a long is 8 bytes.

I assume this means there is existing code out there that expects the current not-as-documented behavior. There is also code out there that expects the documented behavior but behaves wrong when a 64bit Python is used.

I assume I should just fix the documentation and anything in Lib that uses the struct module incorrectly (zipfile for example) rather than change the behavior?

+1 (actually +100) from me. Thomas

Gregory P. Smith wrote:

The documentation for the struct module says:

http://docs.python.org/dev/library/struct.html#module-struct

" short is 2 bytes; int and long are 4 bytes; long long ( __int64 on Windows) is 8 bytes"

and lists 'l' and 'L' as the pack code for a C long.

As its implemented today, the documentation is incorrect. On an LP64 host (pretty much any 64-bit linux, bsd or unixish thing) a long is 8 bytes.

You overlooked the words "Standard size and alignment are as follows" that start the quoted paragraph. It's a little confusing because standard size is not the default. The default is platform-specific sizes. Only if you start the format string with >, <, ! or = do you get standard sizes. The reference documentation is correct as it stands, and, I suspect, so is the LP64 implementation. Doesn't struct.pack('>l',42) produce a 4-byte string on LP64? The tutorial at http://docs.python.org/tut/node13.html#SECTION0013300000000000000000%3E has a bug though: the format string should use '<'. I believe zipfile.py correctly uses '<' throughout. regards, Anders