Packing a simple dictionary into a string - extending struct?

[John Machin]

On Jun 22, 5:08 pm, Jonathan Fine <j... at pytex.org> wrote:
> Jonathan Fine wrote:
> > Thank you for this suggestion.  The growing adoption of JSON in Ajax
> > programming is a strong argument for my using it in my application, although
> > I think I'd prefer something a little more binary.
>
> > So it looks like I'll be using JSON.
>
> Well, I tried.  But I came across two problems (see below).
>
> First, there's bloat.  For binary byte data, one average one
> character becomes just over 4.
>
> Second, there's the inconvenience.  I can't simple take a
> sequence of bytes and encode them using JSON.  I have to
> turn them into Unicode first.  And I guess there's a similar
> problem at the other end.
>
> So I'm going with me own solution:http://mathtran.cvs.sourceforge.net/mathtran/py/bytedict.py?revision=...
>

def unpack(bytes, unpack_entry=unpack_entry):
    '''Return dictionary gotten by unpacking supplied bytes.
    Both keys and values in the returned dictionary are byte-strings.
    '''
    bytedict = {}
    ptr = 0
    while 1:
        key, val, ptr = unpack_entry(bytes, ptr)
        bytedict[key] = val
        if ptr == len(bytes):
                break
# That's beautiful code -- as pretty as a cane-toad.
# Well-behaved too, a very elegant response to unpack(pack({}))
# Try this:
    blen = len(bytes)
    while ptr < blen:
        key, val, ptr = unpack_entry(bytes, ptr)
        bytedict[key] = val

    return bytedict

HTH,
John