Conversion of perl unpack code to python - something odd

[Andrew Robert]

Hey everyone,


Maybe you can see something I don't.

I need to convert a working piece of perl code to python.

The perl code is:

sub ParseTrig {
  # unpack the ibm struct that triggers messages.
  my $struct = shift;

  my %data;
  @data{qw/StructID Version QName ProcessName TriggerData ApplType
ApplId EnvData UserData QMgrName/} =
    unpack("A4A4A48A48A64A4A256A128A128A48", $struct);

  return undef unless $data{StructID} eq 'TMC';

  return \%data;


Taking away the fact that it is a function, the base code sets a 732
element structure with the ascii pattern derived above.

I wrote a simple test script that accepts the command argument at
position 1.



#!C:\Python24\python
import sys, string, struct

# From the language declarations in manual, the following format was derived

format='4s 4s 48s 48s 64s 4s 256s 128s 128s 48s'
size=struct.calcsize(format)

# Extract list item out for convenience/readability
data=sys.argv[1]

# Calculated size of the struct format is 732
# Length of data string is 732

print len(data)
print size

d1,d2=struct.unpack(format,data)
print d1
sys.exit(0)


When I run it, it says there are too many values to unpack.



Traceback ( most recent call last)
  File "m:\mq\mq\scripts\format.py", line 32, in ?
    d1, d2 = struct.unpack(format,data)
ValueError: too many values to unpack
Error starting triggered application




I checked the manual on the structure used to pack the code and it
appears correct.

#
# MQTMC2 Language declarations as defined chapt 22 of programmers ref
# http://publibfp.boulder.ibm.com/epubs/pdf/csqzak09.pdf
#
# CHAR4   Struct ID
# CHAR4   Version
# CHAR48  QName
# CHAR48  ProcessName
# CHAR64  TriggerData
# CHAR4   ApplType
# CHAR256 ApplID
# CHAR128 EnvData
# CHAR128 UserData
# CHAR48  QMgrName


Any help you can provide on this would be greatly appreciated.