On 6/30/14, 2:06 PM, Kim Gräsman wrote:
Hi all,
I'm working on making pymake Python 3-compatible, while still
maintainin Python 2 support (work in progress here:
https://github.com/mozilla/pymake/)
I've addressed most minor issues, but there's two I don't feel
comfortable with: dict.iteritems() vs dict.items() and range vs.
xrange.
In Python 3, items(), keys() and values() on dict no longer return
lists, but rather lazy generators. The same goes for range(), it's now
lazy and assumes the behavior of Python 2's xrange(), which no longer
exists.
This is nice, except it makes cross-compatible code much harder, since
all functions exist in both Python versions but have very different
semantics.
I'm guessing you won't like the Python 2 code to always use eager
items, keys, value and range, because it would take its toll on memory
consumption and unnecessary copies.
Do you have any ideas for version-agnostic patterns?
The generally accepted solution is either:
1) Use 2to3 to produce a copy of the code that is Python 3 compatible
and then run the copy
2) Use six [1] (or similar compatibility layer) to abstract iteritems, etc
I'm a huge fan of a single code base without a 2to3 copy. I also prefer
to not introduce six or similar shims unless it's absolutely necessary:
I'd rather the code be readable, vanilla Python.
If there is no or a small performance hit switching iteritems() and
friends to their non-iter-on-python-2 equivalents, I'm fine with doing
that. Have you measured the differences on a real project (such as Firefox)?
[1] http://pythonhosted.org/six/
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