Simplify Python setup process

Author: awvwgk

python/README.rst

@@ -108,6 +108,11 @@ Install the project with pip
 
    pip install .
 
+If you already have a ``s-dftd3`` installation, *e.g.* from conda-forge, you can build the Python extension module directly without cloning this repository
+
+.. code:: sh
+   pip install "https://github.com/awvwgk/simple-dftd3/archive/refs/heads/main.zip#egg=dftd3-python&subdirectory=python"
+
 
 
 Using meson

python/build.py

@@ -32,10 +32,16 @@
 import os
 import cffi
 
+library = "s-dftd3"
+include_header = '#include "dftd3.h"'
+prefix_var = "SDFTD3_PREFIX"
+if prefix_var not in os.environ:
+    prefix_var = "CONDA_PREFIX"
+
 if __name__ == "__main__":
     import sys
 
-    kwargs = dict(libraries=["s-dftd3"])
+    kwargs = dict(libraries=[library])
 
     header_file = sys.argv[1]
     module_name = sys.argv[2]
@@ -44,22 +50,33 @@
         cdefs = f.read()
 else:
     import subprocess
-    import pkgconfig
-
-    if not pkgconfig.exists("s-dftd3"):
-        raise Exception("Unable to find pkg-config package 's-dftd3'")
-    if pkgconfig.installed("s-dftd3", "< 0.4"):
-        raise Exception(
-            "Installed 's-dftd3' version is too old, 0.4 or newer is required"
-        )
-
-    kwargs = pkgconfig.parse("s-dftd3")
-
-    if "CC" not in os.environ:
-        raise Exception("This build script requires to set a C compiler in CC")
-    cc = os.environ["CC"]
 
-    cflags = pkgconfig.cflags("s-dftd3").split()
+    try:
+        import pkgconfig
+
+        if not pkgconfig.exists(library):
+            raise ModuleNotFoundError("Unable to find pkg-config package 's-dftd3'")
+        if pkgconfig.installed(library, "< 0.4"):
+            raise Exception(
+                "Installed 's-dftd3' version is too old, 0.4 or newer is required"
+            )
+
+        kwargs = pkgconfig.parse(library)
+        cflags = pkgconfig.cflags(library).split()
+
+    except ModuleNotFoundError:
+        kwargs = dict(libraries=[library])
+        cflags = []
+        if prefix_var in os.environ:
+            prefix = os.environ[prefix_var]
+            kwargs.update(
+                include_dirs=[os.path.join(prefix, "include")],
+                library_dirs=[os.path.join(prefix, "lib")],
+                runtime_library_dirs=[os.path.join(prefix, "lib")],
+            )
+            cflags.append("-I" + os.path.join(prefix, "include"))
+
+    cc = os.environ["CC"] if "CC" in os.environ else "cc"
 
     module_name = "dftd3._libdftd3"
 
@@ -69,12 +86,12 @@
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
     )
-    out, err = p.communicate(b'#include "s-dftd3.h"')
+    out, err = p.communicate(include_header.encode())
 
     cdefs = out.decode()
 
 ffibuilder = cffi.FFI()
-ffibuilder.set_source(module_name, '#include "s-dftd3.h"', **kwargs)
+ffibuilder.set_source(module_name, include_header, **kwargs)
 ffibuilder.cdef(cdefs)
 
 if __name__ == "__main__":

python/setup.cfg

@@ -26,8 +26,6 @@ classifiers =
 
 [options]
 packages = find:
-setup_requires =
-    pkgconfig
 install_requires =
     cffi
     numpy