Help needed with translating perl to python

[attn.steven.kuo at gmail.com]

On Jun 26, 8:04 am, vj <vinjv... at gmail.com> wrote:
> I have a perl script which connect to network stream using sockets.
> The scripts first logins in to the server and then parses the data
> comming from the socket.
>
> Statement 1:
>   my $today = sprintf("%4s%02s%02s", [localtime()]->[5]+1900,
> [localtime()]->[4]+1, [localtime()]->[3]) ;


Perl has "Do What I Mean" features that allow you to
treat strings and number interchangeably.  Python's
time.localtime returns a tuple of integers so you'll
have to use the proper format conversion characters:

import time
today = "%04d%02d%02d" % time.localtime()[0:3]

# No need to add offsets of 1900 and 1 because Python
# does this for you



>
> Statement 2:
>   my $password = md5_hex("$today$username") ;


You should have added that md5_hex is comes from
Digest::MD5, not a core Perl module.  Regardless:


import md5
password = md5.new("%s%s" % (today, username)).hexdigest()

# seems to be what you wanted



> Statement group 3:
>
> $msglen = bcdlen(length($msg)) ;
>
> sub bcdlen {
>   my $strlen = sprintf("%04s", shift) ;
>   my $firstval = substr($strlen, 2, 1)*16 + substr($strlen, 3, 1) ;
>   my $lastval  = substr($strlen, 0, 1)*16 + substr($strlen, 1, 1) ;
>   return chr($firstval) . chr($lastval) ;
>
> }




You can have a variadic function in Python but the parameters
are passed via a tuple.  Because a tuple is immutable, one cannot
"shift" elements out of a tuple.  Here I've used the first parameter
via selection by index.  Perl's substr is replaced by slice notation;
chr is, well, chr.  Concatenation (Perl's '.' operator) is replaced
by string formatting:

>>> def bcdlen(*args):
...     strlen = "%04s" % str(args[0])
...     firstval = int(strlen[2:3]) * 16 + int(strlen[3:4])
...     lastval  = int(strlen[0:1]) * 16 + int(strlen[1:2])
...     return "%s%s" % (chr(firstval), chr(lastval))
...
>>> bcdlen(4546)
'FE'


--
Hope this helps,
Steven