Google releasing a constraint programming library

As an Operation Research engineer/PhD student, I was very interested to discover that Google just released a project in my field. It is simply called "or-tools" and contains a constraint programming solver.

While CP is not my primary field of study, I know the basics and I gave a quick look, just in order to know how big it was and what I would fine inside. Technically, I liked what I saw: What is actually inside is C++, wrapped in a swig interface. There are 58 C++ files (24 of them are headers) and a total number of 35998 lines of code, which is reasonable (= rather big, but still readable by 1/2 persons) for a project in this language. Embedding C++ in script languages is probably the best way I know to get the best of the two worlds since you get the power of scripts, and the speed of C++. While this technique is very efficient and more and more projects are using it, Operations Research is a field where things are usually moving slowly in terms of technology, so I was glad to see that google engineers are doing it, it might show the way for the rest of the community.

The project is supposed to build on the 3 major platforms. For linux, it just uses a simple Makefile, which I liked even more: Having used autotools a lot, I think I can now say I only have pure hate for them (they never made things simpler) and I just want to hug every programmers that are handling things with simple Makefiles.

There are examples in python and in C++ that are classic CP exercises for students (at least I already knew most of them). The only thing I did not like was the fact they are using subversion. I find it easier to hack in projects when they are distributed with DCVS. But I guess the guys who did this don't need my opinion, since it is not the first time they are writing code. I was curious and googled the name of the commiter: apparently he's a former engineer from ilog (now part of IBM), which is famous in the OR field for cplex, the famous MIP solver.

There are a mailing list: and a website:,

so I guess google also plans to maintain this library. Conclusion: Good news for OR!

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