Migrating to the new application programmers’ interface

This is a short guide to migrating to the new application programmers’ interface (API) and build system for XCFun. We assume that you have successfully built and tested XCFun and installed it to <install-prefix>. The layout of the install tree will be as follows:

<install-prefix>/
                ├── include
                │   └── XCFun
                │       ├── config.hpp
                │       ├── densvars.hpp
                │       ├── functional.hpp
                │       ├── functionals
                │       ├── specmath.hpp
                │       ├── XCFunctional.hpp
                │       ├── XCFunExport.h
                │       ├── xcfun.f90
                │       ├── xcfun.h
                │       └── xcint.hpp
                ├── lib
                │   └── python
                │       └── xcfun
                ├── lib64
                │   ├── libxcfun.a
                │   ├── libxcfun.so -> libxcfun.so.2
                │   └── libxcfun.so.2
                └── share
                    └── cmake
                        └── XCFun

C/C++ host programs

Types and function signatures are in the header file xcfun.h.

In your source code, apply the following changes:

• Remove any of the calls to the functions that have been removed from the API. Open an issue if these functions are essential to your workflow and you would like them to be reinstated.

• Replace xc_functional with xcfun_t *.

• Replace xc_new_functional with xcfun_new.

• Replace xc_enumerate_parameters with xcfun_enumerate_parameters.

• Replace xc_enumerate_aliases with xcfun_enumerate_aliases.

• Replace xc_set with xcfun_set.

• Replace xc_get with xcfun_get.

• Replace xc_describe_short with xcfun_describe_short.

• Replace xc_describe_long with xcfun_describe_long.

• Replace xc_is_gga with xcfun_is_gga.

• Replace xc_is_metagga with xcfun_is_metagga.

• Replace xc_eval_setup with xcfun_eval_setup.

• Replace xc_user_eval_setup with xcfun_user_eval_setup.

• Replace xc_input_length with xcfun_input_length.

• Replace xc_output_length with xcfun_output_length.

• Replace xc_eval with xcfun_eval.

• Replace xc_eval_vec with xcfun_eval_vec.

Fortran host programs

The Fortran/C interoperability layer for types and function signatures is in the source file xcfun.f90.

In your source code, apply the following changes:

• Use the intrinsic iso_c_binding module: use, intrinsic :: iso_c_binding.

• Remove any of the calls to the functions that have been removed from the API. Open an issue if these functions are essential to your workflow and you would like them to be reinstated.

• You should call the intrinsic trim on functions returning strings: xcfun_version, xcfun_splash, xcfun_authors, xcfun_enumerate_paramters, xcfun_enumerate_aliases, xcfun_describe_short, xcfun_describe_long.

• Replace the type for the xc_functional object (now xcfun_t *) from integer to type(c_ptr).

• Replace xc_new_functional with xcfun_new.

• Replace xc_enumerate_parameters with xcfun_enumerate_parameters.

• Replace xc_enumerate_aliases with xcfun_enumerate_aliases.

• Replace xc_set with xcfun_set.

• Replace xc_get with xcfun_get.

• Replace xc_describe_short with xcfun_describe_short.

• Replace xc_describe_long with xcfun_describe_long.

• Replace xc_is_gga with xcfun_is_gga.

• Replace xc_is_metagga with xcfun_is_metagga.

• Replace xc_eval_setup with xcfun_eval_setup.

• Replace xc_user_eval_setup with xcfun_user_eval_setup.

• Replace xc_input_length with xcfun_input_length.

• Replace xc_output_length with xcfun_output_length.

• Replace xc_eval with xcfun_eval.

• Replace xc_eval_vec with xcfun_eval_vec.