[Python-Dev] Lazy unpacking for struct module (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Mon Jun 13 23:54:17 CEST 2011

Raymond Hettinger wrote:

How would you describe the creation of a lazy result that keeps a reference to the underlying buffer?

I'd call it a view. There is plenty of precedence for this kind of object in Python -- I gave a few examples before.

The distinguishing feature of ropes, as I understand the term, is that you get a lazy object when you combine other objects, e.g. concatenating strings.

That's not being asked for here -- there is only taking apart going on, not putting together.

It's also different from the oft-rejected idea of lazy string slicing, because extracting a field would give you a separate object, e.g. an int or string, not a reference to the original data object being unpacked.

So I really can't see what harm it could do, except for maybe a tiny performance reduction in the case where you extract all the fields, or refer to extracted fields repeatedly.

Even if that turned out to be the case, and was considered objectionable, it could still be useful to provide view-oriented unpacking as an option.

-- Greg

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