How about making offset a standard integer, and change the signature to return tuple when it is used: item, offset = unpack(format, rec, offset) # Partial unpacking
Well, it would work well when unpack results are assigned to individual vars:
x,y,offset=unpack( "ii", rec, offset)
but it gets more complicated if you have something like: coords=unpack("10i", rec)
How would you pass/return offsets here? As an extra element in coords? coords=unpack("10i", rec, offset) offset=coords.pop()
But that would be counterintuitive and somewhat inconvinient..
I was thinking more along the lines of returning a 2-tuple with the 'normal' result of unpack as the first element:
coords, offset = unpack("ii", rec, offset)
x, y = coordsRaymond's suggestion of a separate function like 'unpack_here' is probably a good one, as magically changing function signatures are evil. Something like:
def unpack_here(format, record, offset = 0): end = offset + calcsize(format) return (unpack(format, record[offset:end]), end)
Presumably, a C version could avoid the slicing and hence be significantly more efficient.
Yes, the return type is a little clumsy, but it should still make it easier to write more efficient higher-level API's that unpack the structure a piece at a time.
Cheers, Nick.
--
Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia
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http://boredomandlaziness.skystorm.net
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