Describing a fixed length field #39

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1. posborne commented on May 19, 2016

   

   posborne

   on May 19, 2016

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   I think UBInt8Sequence should work for this. It appears that it doesn't show up in the docs as it is generated by a factory (https://digidotcom.github.io/python-suitcase/latest/_modules/suitcase/fields.html#BaseFixedByteSequence). It expects a sequence of bytes (e.g. [1, 2, 3, 4, 5, 6, 7, 8]), so some conversion will be required if you have an actual bytes payload.

   👍React with 👍4Reacted by Nick Stevens, Óscar Curero, Ryan Zoeller and Vegard Haugland
2. ocurero commented on May 20, 2016

   

   ocurero

   on May 20, 2016

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   Thanks Paul!

   It works, but something is still wrong. If I try the way you say:

   IRM_RACF_GRNAME = BaseFixedByteSequence(lambda x: str(x) + 's', 8)

   I get the following error:

     File "./testproto.py", line 153, in client
       printb(a.pack())
     File "/home/oscar/env/lib/python2.7/site-packages/suitcase/structure.py", line 303, in pack
       return self._packer.pack()
     File "/home/oscar/env/lib/python2.7/site-packages/suitcase/structure.py", line 28, in pack
       self.write(sio)
     File "/home/oscar/env/lib/python2.7/site-packages/suitcase/structure.py", line 41, in write
       field.pack(stream)
     File "/home/oscar/env/lib/python2.7/site-packages/suitcase/fields.py", line 889, in pack
       raise SuitcasePackStructException(e)
   suitcase.exceptions.SuitcasePackStructException: pack requires exactly 1 arguments
   

   To make it work I need to change the way self._value is passed to pack:

   Original version not working (line 887 in fields.py):
   stream.write(struct.pack(self.format, *self._value))

   Modified version working (same line 887 in fields.py):
   stream.write(struct.pack(self.format, self._value))

   If the fix is ok, BaseVariableByteSequence has the same problem.

   👍React with 👍1Reacted by Vegard Haugland
3. v3gard commented on Oct 5, 2016

   

   v3gard

   on Oct 5, 2016

   Last edited by v3gard

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   ocurero's suggestion is a nice workaround, but it would be great if you could implement a FixedByteSequence(number_of_bytes) field in the next version of suitcase.