Pyomo5 Expressions

[Bill Hart]

Hi, all:

I have been making progress with a new expression system for Pyomo (called "Pyomo5") that addresses some performance issues in Pyomo and seamlessly supports PyPy.

I'm actively merging commits from Pyomo's master branch to the expr_dev branch where this capability is being developed.  And I'd like to work with developers this month to confirm that their code that walks expression trees has been reworked.

As part of those discussions, I'd like to review the design of Pyomo5 expressions.  I've added documentation for these expressions on the expr_dev branch, which can be viewed here:

 http://pyomo.readthedocs.io/en/expr_dev/developer_reference/expressions/index.html

I consider this design a working draft, and I've already gotten some critical feedback about various aspects of it.  Please reply here or send me a note directly with questions and concerns.

Finally, I'd like to host a review of this design on December 12th at 12 noon MT.  I'll send out details later for how to call-in.

FYI, I'm not sure when this new capability will be merged into the Pyomo master branch.  There are some competing development activities this month, so this might not happen until mid-January.

Cheers,

--Bill

[Michael Bynum]

Bill, 

The persistent solver interfaces may need to be updated. I'm still working on tests for these (which will have to be run on Jenkins?), so you won't see test failures on travis even if they are not updated. Right now, I am not walking the expression tree for these solvers. Instead, I am using get_canonical_repn. With pyomo5, will get_canonical_repn still be supported? If not, do I need to walk the expression tree?

Thanks,

Michael

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[Bill Hart]

In Pyomo5 expressions, you will be able to call get_standard_repn, which is a generalization of the get_ampl_repn logic supported on the Pyomo master branch.

--Bill

[Michael Bynum]

 Perfect. Thanks Bill. That should be an easy update then. 

Michael