Precompiling Eigen Headers

Question

I am building a C++ project using Eclipse on Windows OS, I am also using the Eigen Linear Algebra library. My problem is with the very slow compiling time of Eigen (about 50 sec).

I've tried these proposed solutions:

• Precompiled headers in Eclipse: unfortunately didn't work with me
• The Amazing Ruby: Precompiled Header Hack for Eclipse CDT: it reduced the compiling time with 5 sec
• #define EIGEN_NO_DEBUG: it reduced the time with additional 3 seconds

I really need a solution for this, it's very unpractical to wait 47 sec each time I build the project to test something.

Any idea is deeply appreciated, thanks.

Answer 1

Eigen is a template library, meaning that the classes are defined based on the template parameters. I don't think that you would be able to precompile without letting the compiler know exactly all the possible classes you would need in your entire code base.

Alternatively, you could write a wrapper for Eigen and declare all the types you want and use that library. HOWEVER, you are likely to lose a lot of Eigen's advantages (see here, here and others).