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[Python-Dev] struct.pack inconsistencies between platforms
pmon mailpmon.mail at gmail.com
Sun Feb 26 14:45:52 CET 2012
Sounds reasonable for me. Thanks!On Sun, Feb 26, 2012 at 3:16 PM, Eli Bendersky <eliben at gmail.com> wrote:>>> On Sun, Feb 26, 2012 at 15:09, Paul Moore <p.f.moore at gmail.com> wrote:>>> On 26 February 2012 12:34, Eli Bendersky <eliben at gmail.com> wrote:>> > On Sun, Feb 26, 2012 at 12:33, pmon mail <pmon.mail at gmail.com> wrote:>> >> Documentation clearly states that the 'L' is a 4 byte integer.>> >>>> >> Is this a bug? I'm I missing something?>> >>>> >>> > By default pack uses native size, not standard size. On a 64-bit>> machine:>>>> As the OP points out, the documentation says that the "Standard Size">> is 4 bytes (http://docs.python.org/library/struct.html). While>> "Standard Size" doesn't appear to be defined in the documentation, and>> the start of the previous section (7.3.2.1. Byte Order, Size, and>> Alignment) clearly states that C types are represented in native>> format by default, the documentation could probably do with some>> clarification.>>>>> 7.2.3.1 says, shortly after the first table:>> ">> Native size and alignment are determined using the C compiler’s sizeofexpression. This is always combined with native byte order.>> Standard size depends only on the format character; see the table in the *Format> Characters* <http://docs.python.org/library/struct.html#format-characters>section.> ">> To me this appears to be a reasonable definition of what "standard size"> is.>> 7.3.2.2 says before the size table:>> "Format characters have the following meaning; the conversion between C> and Python values should be obvious given their types. The ‘Standard size’> column refers to the size of the packed value in bytes when using standard> size; that is, when the format string starts with one of '<', '>', '!' or> '='. When using native size, the size of the packed value is> platform-dependent.">> Again, taken together with the previous quote, IMHO this defines the> difference between standard and native sizes clearly. If you feel> differently, feel free to open an issue suggesting a better explanation.>> Eli>>>>-------------- next part --------------An HTML attachment was scrubbed...URL: <http://mail.python.org/pipermail/python-dev/attachments/20120226/60074c8e/attachment.html>
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