Set include-path for header only library installed with conda

Question

I was recently advised to check out conda as a package manager. Unfortunately I don't succeed in finding how to make my compiler find a header-only library installed with conda? Ideally I would like to not having to manually specify a path to my compiler at all.

(The context is that I come from homebrew on macOS, which creates symbolic links on the right locations. Obviously this is what conda avoids. But still, a simple way to compile simple examples would be nice!)

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Example

For example, if my code is the one below. Note: this question is meant to be generic, not related to a specific package, nor do I want to have to manually specify again my specific virtual environment.

#include <iostream>
#include <xtensor/xarray.hpp>
#include <xtensor/xio.hpp>

int main()
{
  xt::xarray<double> a
    {{1.0, 2.0, 3.0},
     {2.0, 5.0, 7.0},
     {2.0, 5.0, 7.0}};

  std::cout << a;
}

I have 'installed' the library using

conda create --name example
source activate example
conda install -c conda-forge xtensor-python

Now I would like to compile just with

clang++ -std=c++14 test.cpp

Note that I know that this works:

clang++ -std=c++14 -I~/miniconda3/envs/example/include test.cpp

But I don't think that this is wanted, because:

• The path includes the environment (example).
• It is system dependent.

Dynamiter

If there is a system environment variable that sets include paths, you can set that when the environment is activated – Erective

@Erective Thanks for your reply. I guess a big deficiency is that there is no such environment variable. I could, of course, introduce my own environment variable, say ${INCLUDEPATH}. If I were to do that, how can I set it based on the virtual environment? – Dynamiter

https://mcmap.net/q/382101/-conda-set-ld_library_path-for-env-only-duplicate – Erective

@Erective Nice, thanks a lot. – Dynamiter

Answer 1

At least on unix systems, a solution would be to use

clang++ -std=c++14 -I"${CONDA_PREFIX}"/include test.cpp

thereby "${CONDA_PREFIX}" point to the root of the current conda environment. In this case:

~/miniconda3/envs/example

Dynamiter

Answer 2

I would rather export CPATH or CPLUS_INCLUDE_PATH variable to add ${CONDA_PREFIX}/include : it would untangle compilation process (compiling test.cpp) from conda environment allowing portability of your compilation process.

CPATH If this environment variable is present, it is treated as a delimited list of paths to be added to the default system include path list. The delimiter is the platform dependent delimiter, as used in the PATH environment variable.

C_INCLUDE_PATH, OBJC_INCLUDE_PATH, CPLUS_INCLUDE_PATH, OBJCPLUS_INCLUDE_PATH These environment variables specify additional paths, as for CPATH, which are only used when processing the appropriate language.

Use https://docs.conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html?highlight=env#setting-environment-variables to set environment variables.

$ conda env config vars set CPATH=${CONDA_PREFIX}/include:${CPATH}

Contented

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