Update the warning about transporting marshals across boxes with different

ideas about sizeof(long).
This commit is contained in:
Tim Peters 2001-09-14 20:40:13 +00:00
parent c785f4841c
commit ad2dc3fc44
1 changed files with 8 additions and 13 deletions

View File

@ -39,19 +39,14 @@ therein are themselves supported; and recursive lists and dictionaries
should not be written (they will cause infinite loops).
\strong{Caveat:} On machines where C's \code{long int} type has more than
32 bits (such as the DEC Alpha), it
is possible to create plain Python integers that are longer than 32
bits. Since the current \module{marshal} module uses 32 bits to
transfer plain Python integers, such values are silently truncated.
This particularly affects the use of very long integer literals in
Python modules --- these will be accepted by the parser on such
machines, but will be silently be truncated when the module is read
from the \file{.pyc} instead.\footnote{
A solution would be to refuse such literals in the parser,
since they are inherently non-portable. Another solution would be to
let the \module{marshal} module raise an exception when an integer
value would be truncated. At least one of these solutions will be
implemented in a future version.}
32 bits (such as the DEC Alpha), it is possible to create plain Python
integers that are longer than 32 bits.
If such an integer is marshaled and read back in on a machine where
C's \code{long int} type has only 32 bits, a Python long integer object
is returned instead. While of a different type, the numeric value is
the same. (This behavior is new in Python 2.2. In earlier versions,
all but the least-significant 32 bits of the value were lost, and a
warning message was printed.)
There are functions that read/write files as well as functions
operating on strings.