Documentation: include how to compile the C++ Examples

[RemiLehe]

I found the examples very instructive.

However, as someone who knows almost nothing besides Python (shame on me!), it is unclear how to compile/test the examples. Having installed openpmd-api (from source+cmake) in /usr/local/, my naive attempt was:

g++ -I/usr/local/include/ -L/user/local/lib/ -lopenPMD 2_read_serial.cpp 

Could you add the correct command in the documentation?

[ax3l]

Thanks for the feedback!

So far we have the linking to your project section in the README.md which recommends using CMake downstream.

If you want to link manually, you probably have to add a few defines such as -DopenPMD_USE_MPI=ON in case you added support for it at runtime. (We can add an old-style pkg-config/.pc file for this to assist.)

What kind of error did you get with the command above? Your command would be correct for a shared lib.

In case you installed openPMD-api statically, the compiler just adds the static lib like any other source file:

g++ -I/usr/local/include/ 2_read_serial.cpp /user/local/lib/libopenPMD.a

What's the install method you used and which version of openPMD-api did you install?

[RemiLehe]

Thanks for the quick answer!

Recommending CMake definitely makes sense ; however, for my particular use case, this is not an option.

You were right: I had built the openPMD library statically (using CMake here). So, in the end, the following command did the trick:

g++ -I/usr/local/include/ -std=c++11 -lhdf5 3_write_serial.cpp /usr/local/lib/libopenPMD.a 

[ax3l]

Yes, that makes sense.

Manual linking is not really comfortable, since I/O dependency stacks are long and deep.

We can reduce that burden a little for manual linking by also installing a .pc file. With its help, manual building would look something like:

g++ 3_write_serial.cpp $(pkg-config --libs --cflags openPMD-api)

as long as the environment variable PKG_CONFIG_PATH is properly expanded and you have the pkg-config tool on the system (most unix do).

It's a bit painful to create them with all the corner cases (such as with/without rpaths) and transient dependencies, but if it helps we can try that.

[ax3l]

Implemented .pc file helpers in #532 #535 #580