Python2.2 + mailbox. Bug????

[Noam Raphael]

hector wrote:
> Hi
> 
>   This is my program:
> 
> #!/usr/bin/python
> import sys
> from mailbox import PortableUnixMailbox
> tmp = sys.stdin
> mbox = PortableUnixMailbox(tmp)
> mbox.next()
> ...
> ...
> 
>   When I execute: "./program.py < mboxfile.txt", there's no problem
> 
>   But, if I execute: "cat mboxfile.txt | program.py" ... too bad!
> 
>   the error:
> 
> Traceback (most recent call last):
>   File "./prueba.py", line 8, in ?
>     mbox.next()
>   File "/usr/lib/python2.2/mailbox.py", line 23, in next
>     self.fp.seek(self.seekp)
> IOError: [Errno 29] Illegal seek
> 
> Why????? Thanks ALL!!

Hello,
I assume that when you write "./program.py < mboxfile.txt", Python knows 
that sys.stdin is a regular file, so it can do seek on it (for example, 
go back to its beginning). When you write "cat mboxfile.txt | 
program.py", the program cat outputs the file mboxfile.txt into 
sys.stdin byte by byte, so you can't do seek on it.

Bye,
Noam