UFL doesn't use __metaclass__ but it uses __new__, is the behaviour of that the same? I'd like to clean up those parts at some point but I won't have time before the summer.
If we have to change behaviour of Expression we should consider doing that simultaneously with the introduction of an Expression-like ufl type which will have several advantages. Martin On 23 May 2014 12:24, Johan Hake <[email protected]> wrote: > And then there is the change of syntax for metaclasses in Python3... Just > goggle metaclass python 3 and there are several pointers to the different > syntax. > > Maybe this will be a good point to throw out the usage of metaclasses in > DOLFIN? What we need is to add a distinction between CompiledExpression and > Expression. I have tried this before with no luck ;) > > Johan > > > On Thu, May 22, 2014 at 11:40 AM, Martin Sandve Alnæs > <[email protected]>wrote: > >> Yes, and if we're lucky we can get to that point without as much work as >> sympy, since we don't have as much code. >> >> The 2to3 tool can do selective changes like change print "" to print("") >> and fix exception syntax, which are compatible with 2.7. >> >> It can also do things like change "a = dict.iteritems()" into "a = >> dict.items()" which changes the memory usage when run on 2.7. These >> differences can instead be resolved by using the python module "six" which >> implements cross-compatible helper functions for a lot of things. >> >> Btw when we switch we should go straight to python 3.3-3.4. >> Supporting 3.0-3.2 side by side with 2.7 is apparently harder. >> >> (Note to Aslak: read the link from Jan!) >> >> Martin >> >> >> On 22 May 2014 11:22, Jan Blechta <[email protected]> wrote: >> >>> Note that there is also an approach of having simultaneously 2.x and 3.x >>> compatible codebase without a need of using 2to3. Allegedly, this is >>> used in SymPy, NumPy and SciPy projects. See >>> >>> http://ondrejcertik.blogspot.cz/2013/08/how-to-support-both-python-2-and-3.html >>> >>> Jan >>> >>> >>> On Thu, 22 May 2014 11:05:43 +0200 >>> Martin Sandve Alnæs <[email protected]> wrote: >>> >>> > The plan for the initial work here is to keep the code python 2.7 >>> > compatible but ready for a later swift switch to 3 only. I suggest we >>> > release fenics 1.5 with python 2.7 compatibility intact but >>> > convertible to python 3 by just running py2to3. Otherwise there will >>> > be too much simultaneous breakage. Then we can discuss whether we >>> > leave python 2.7 behind in fenics 1.6 or not. >>> > >>> > However, I haven't thought about the swig side in dolfin, and as Johan >>> > mentions keeping the Python CAPI code compatible is not covered by >>> > py2to3. I'll discuss this with Johan and Aslak. >>> > >>> > Martin >>> > >>> > >>> > On 22 May 2014 10:49, Garth N. Wells <[email protected]> wrote: >>> > >>> > > Nice. Do we want to support Python 2.7 and 3, or would it be more >>> > > sustainable to go all Python 3? My preference is for simplicity and >>> > > low maintenance, which points to Python 3 only support. >>> > > >>> > > Garth >>> > > On Thu, 22 May, 2014 at 9:39 AM, Martin Sandve Alnæs >>> > > <[email protected]> wrote: >>> > > >>> > >> We have a summer intern at Simula, Aslak Bergersen, >>> > >> who will work on preparations for python 3 support in FEniCS, >>> > >> as well as some other FEniCS tasks, from late June and >>> > >> throughout July. >>> > >> >>> > >> The preparations for python 3 involves mainly: >>> > >> - Replacing ScientificPython for AD in FIAT >>> > >> - Applying and committing backwards compatible parts of py2to3 >>> > >> - Replacing several functions such as dict.iteritems with >>> > >> six.iteritems in UFL and possibly FFC to make sure we keep the >>> > >> same performance and memory behaviour with python 2 and 3. >>> > >> >>> > >> I will be on vacation part of his time here so please >>> > >> help him out if he has questions to the list. >>> > >> >>> > >> Martin >>> > >> >>> > > >>> > > >>> >>> >> >> _______________________________________________ >> fenics mailing list >> [email protected] >> http://fenicsproject.org/mailman/listinfo/fenics >> >> >
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