modifying a standard module? (was: Re: tarfile : read from a socket?)

[Ulli Horlacher]

Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:

> This code works so far:
> 
>   sfo = sock.makefile('r')
>   taro = tarfile.open(fileobj=sfo,mode='r|')
>   taro.extractall(path=edir)
> 
> But it does not writes anything to the terminal to inform the user.
> 
> When I use:
> 
>   for member in taro.getmembers():
>       print('extracting "%s"' % member.name)
>       taro.extract(member)
> 
> I get the error:
> 
>   File "/usr/lib/python2.7/tarfile.py", line 556, in seek
>     raise StreamError("seeking backwards is not allowed")
> 
> Of course, a stream is not seekable.
> 
> Any ideas?

As a hack, I modified the standard library module tarfile.py:

root at diaspora:/usr/lib/python2.7# vv -d
--- ./.versions/tarfile.py~1~   2015-06-22 21:59:27.000000000 +0200
+++ tarfile.py  2016-02-11 18:01:50.185555952 +0100
@@ -2045,6 +2045,7 @@
                 directories.append(tarinfo)
                 tarinfo = copy.copy(tarinfo)
                 tarinfo.mode = 0700
+            print('untar "%s"' % tarinfo.name)
             self.extract(tarinfo, path)
 
         # Reverse sort directories.


This gives me exact the output I want :-)

BUT I want to distribute my program and all others will not see the tar
extracting information.

Now my question:

How can I substitute the standard module function tarfile.extractall() with
my own function?



-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/