[Pythonmac-SIG] convert binary plist to xml string

[Bill Janssen]

> first, second, third, fourth, fifth, ..... = struct.unpack 
> ("iiIIiIiiILllfd", data)
> 
> It is SO EASY to screw this up.  Pick the wrong type code, or  
> misalign the type and field.  It needs to look more like something sane:
> 
> class Point(struct.BigEndianStruct):
>     x = struct.SInt32()
>     y = struct.SInt32()

Why not (for yourself) just add a module which addresses some of this?
As in:

from unpacking import *

def getPoint (bvar):
    unpack = unpacking(bvar)
    x = unpack(S_INT_32)
    y = unpack(S_INT_32)

============================== unpacking.py ============================
import struct

S_INT_32 = "i"
U_INT_32 = "I"
## ... etc. ...

class unpacker:

    def __init__(self, bdata):

        if type(bdata) != type(''):
            raise ValueError("type of bdata (%s) should be simple str" % bdata)
        self.bdata = bdata

    def unpack(self, typespec):

        if not self.bdata:
            raise ValueError("data source exhausted")

        if len(self.bdata) > 0:
            valsize = struct.calcsize(typespec)
            if len(self.bdata) < valsize:
                raise ValueError("data source exhausted")
            val = struct.unpack(typespec, self.bdata[:valsize])
            self.bdata = self.bdata[valsize:]
            return val

def unpacking(bdata):
    return (lambda x, y=unpacker(bdata): y.unpack(x))