Add custom build backend to support build args

This implements a custom build backend, inspired by the [solution used by Pillow.](python-pillow/Pillow#7171) install-option is deprecated and was removed with pip 23.1. The comonly accepted solution seems to be to define a custom build backend for now pypa/setuptools#2491 (comment) This commit changes the usage from `--install-option` to `--config-settings`.
tobiasah · Oct 2, 2023 · d92f1c8 · d92f1c8
1 parent db26d60
commit d92f1c8
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diff --git a/README.md b/README.md
@@ -38,25 +38,27 @@ cd pycapnp
 pip install .
 ```
 
-If you wish to install using the latest upstream C++ Cap'n Proto:
+By default, the setup script will automatically use the locally installed Cap'n Proto.
+If Cap'n Proto is not installed, it will bundle and build the matching Cap'n Proto library.
+
+To enforce bundling, the Cap'n Proto library:
 
 ```bash
-pip install \
-    --install-option "--libcapnp-url" \
-    --install-option "https://github.com/capnproto/capnproto/archive/master.tar.gz" \
-    --install-option "--force-bundled-libcapnp" .
+pip install . -C force-bundled-libcapnp=True
 ```
 
-To force bundled python:
+If you wish to install using the latest upstream C++ Cap'n Proto:
 
 ```bash
-pip install --install-option "--force-bundled-libcapnp" .
+pip install . \
+    -C force-bundled-libcapnp=True \
+    -C libcapnp-url="https://github.com/capnproto/capnproto/archive/master.tar.gz"
 ```
 
-Slightly more prompt error messages using distutils rather than pip.
+To enforce using the installed Cap'n Proto from the system:
 
 ```bash
-python setup.py install --force-bundled-libcapnp
+pip install . -C force-system-libcapnp=True
 ```
 
 The bundling system isn't that smart so it might be necessary to clean up the bundled build when changing versions:
@@ -92,19 +94,12 @@ pipenv run pytest
 
 ### Binary Packages
 
-Building a dumb binary distribution:
-
-```bash
-python setup.py bdist_dumb
-```
-
-Building a Python wheel distributiion:
+Building a Python wheel distributiion
 
 ```bash
-python setup.py bdist_wheel
+pip wheel .
 ```
 
-
 ## Documentation/Example
 
 There is some basic documentation [here](http://capnproto.github.io/pycapnp/).

diff --git a/_custom_build/backend.py b/_custom_build/backend.py
@@ -0,0 +1,31 @@
+import sys
+
+from setuptools.build_meta import *  # noqa: F401, F403
+from setuptools.build_meta import build_wheel
+
+backend_class = build_wheel.__self__.__class__
+
+
+class _CustomBuildMetaBackend(backend_class):
+    def run_setup(self, setup_script="setup.py"):
+        if self.config_settings:
+            flags = []
+            if self.config_settings.get("force-bundled-libcapnp"):
+                flags.append("--force-bundled-libcapnp")
+            if self.config_settings.get("force-system-libcapnp"):
+                flags.append("--force-system-libcapnp")
+            if self.config_settings.get("libcapnp-url"):
+                flags.append("--libcapnp-url")
+                flags.append(self.config_settings["libcapnp-url"])
+            if flags:
+                sys.argv = sys.argv[:1] + ["build_ext"] + flags + sys.argv[1:]
+        return super().run_setup(setup_script)
+
+    def build_wheel(
+        self, wheel_directory, config_settings=None, metadata_directory=None
+    ):
+        self.config_settings = config_settings
+        return super().build_wheel(wheel_directory, config_settings, metadata_directory)
+
+
+build_wheel = _CustomBuildMetaBackend().build_wheel
diff --git a/capnp/lib/capnp_api.h b/capnp/lib/capnp_api.h
@@ -0,0 +1,125 @@
+/* Generated by Cython 0.29.36 */
+
+#ifndef __PYX_HAVE_API__capnp__lib__capnp
+#define __PYX_HAVE_API__capnp__lib__capnp
+#ifdef __MINGW64__
+#define MS_WIN64
+#endif
+#include "Python.h"
+
+static PyObject *(*__pyx_api_f_5capnp_3lib_5capnp_wrap_dynamic_struct_reader)( ::capnp::Response< ::capnp::DynamicStruct> &) = 0;
+#define wrap_dynamic_struct_reader __pyx_api_f_5capnp_3lib_5capnp_wrap_dynamic_struct_reader
+static  ::kj::Promise<void>  *(*__pyx_api_f_5capnp_3lib_5capnp_call_server_method)(PyObject *, char *,  ::capnp::CallContext< ::capnp::DynamicStruct, ::capnp::DynamicStruct> &) = 0;
+#define call_server_method __pyx_api_f_5capnp_3lib_5capnp_call_server_method
+static PyObject *(*__pyx_api_f_5capnp_3lib_5capnp_wrap_kj_exception)( ::kj::Exception &) = 0;
+#define wrap_kj_exception __pyx_api_f_5capnp_3lib_5capnp_wrap_kj_exception
+static PyObject *(*__pyx_api_f_5capnp_3lib_5capnp_wrap_kj_exception_for_reraise)( ::kj::Exception &) = 0;
+#define wrap_kj_exception_for_reraise __pyx_api_f_5capnp_3lib_5capnp_wrap_kj_exception_for_reraise
+static PyObject *(*__pyx_api_f_5capnp_3lib_5capnp_get_exception_info)(PyObject *, PyObject *, PyObject *) = 0;
+#define get_exception_info __pyx_api_f_5capnp_3lib_5capnp_get_exception_info
+static void (*__pyx_api_f_5capnp_3lib_5capnp_promise_task_add_done_callback)(PyObject *, PyObject *, ::kj::PromiseFulfiller<void> &) = 0;
+#define promise_task_add_done_callback __pyx_api_f_5capnp_3lib_5capnp_promise_task_add_done_callback
+static void (*__pyx_api_f_5capnp_3lib_5capnp_promise_task_cancel)(PyObject *) = 0;
+#define promise_task_cancel __pyx_api_f_5capnp_3lib_5capnp_promise_task_cancel
+static void (*__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_write_start)(PyObject *,  ::kj::ArrayPtr< ::kj::ArrayPtr<uint8_t const >  const > , ::kj::PromiseFulfiller<void> &) = 0;
+#define _asyncio_stream_write_start __pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_write_start
+static void (*__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_write_stop)(PyObject *) = 0;
+#define _asyncio_stream_write_stop __pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_write_stop
+static void (*__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_read_start)(PyObject *, void *, size_t, size_t,  ::kj::PromiseFulfiller<size_t>  &) = 0;
+#define _asyncio_stream_read_start __pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_read_start
+static void (*__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_read_stop)(PyObject *) = 0;
+#define _asyncio_stream_read_stop __pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_read_stop
+static void (*__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_shutdown_write)(PyObject *) = 0;
+#define _asyncio_stream_shutdown_write __pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_shutdown_write
+static void (*__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_close)(PyObject *) = 0;
+#define _asyncio_stream_close __pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_close
+static PyObject *(*__pyx_api_f_5capnp_3lib_5capnp_make_async_message_reader)( ::kj::Own< ::capnp::MessageReader> ) = 0;
+#define make_async_message_reader __pyx_api_f_5capnp_3lib_5capnp_make_async_message_reader
+#if !defined(__Pyx_PyIdentifier_FromString)
+#if PY_MAJOR_VERSION < 3
+  #define __Pyx_PyIdentifier_FromString(s) PyString_FromString(s)
+#else
+  #define __Pyx_PyIdentifier_FromString(s) PyUnicode_FromString(s)
+#endif
+#endif
+
+#ifndef __PYX_HAVE_RT_ImportFunction_0_29_36
+#define __PYX_HAVE_RT_ImportFunction_0_29_36
+static int __Pyx_ImportFunction_0_29_36(PyObject *module, const char *funcname, void (**f)(void), const char *sig) {
+    PyObject *d = 0;
+    PyObject *cobj = 0;
+    union {
+        void (*fp)(void);
+        void *p;
+    } tmp;
+    d = PyObject_GetAttrString(module, (char *)"__pyx_capi__");
+    if (!d)
+        goto bad;
+    cobj = PyDict_GetItemString(d, funcname);
+    if (!cobj) {
+        PyErr_Format(PyExc_ImportError,
+            "%.200s does not export expected C function %.200s",
+                PyModule_GetName(module), funcname);
+        goto bad;
+    }
+#if PY_VERSION_HEX >= 0x02070000
+    if (!PyCapsule_IsValid(cobj, sig)) {
+        PyErr_Format(PyExc_TypeError,
+            "C function %.200s.%.200s has wrong signature (expected %.500s, got %.500s)",
+             PyModule_GetName(module), funcname, sig, PyCapsule_GetName(cobj));
+        goto bad;
+    }
+    tmp.p = PyCapsule_GetPointer(cobj, sig);
+#else
+    {const char *desc, *s1, *s2;
+    desc = (const char *)PyCObject_GetDesc(cobj);
+    if (!desc)
+        goto bad;
+    s1 = desc; s2 = sig;
+    while (*s1 != '\0' && *s1 == *s2) { s1++; s2++; }
+    if (*s1 != *s2) {
+        PyErr_Format(PyExc_TypeError,
+            "C function %.200s.%.200s has wrong signature (expected %.500s, got %.500s)",
+             PyModule_GetName(module), funcname, sig, desc);
+        goto bad;
+    }
+    tmp.p = PyCObject_AsVoidPtr(cobj);}
+#endif
+    *f = tmp.fp;
+    if (!(*f))
+        goto bad;
+    Py_DECREF(d);
+    return 0;
+bad:
+    Py_XDECREF(d);
+    return -1;
+}
+#endif
+
+
+static int import_capnp__lib__capnp(void) {
+  PyObject *module = 0;
+  module = PyImport_ImportModule("capnp.lib.capnp");
+  if (!module) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "wrap_dynamic_struct_reader", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp_wrap_dynamic_struct_reader, "PyObject *( ::capnp::Response< ::capnp::DynamicStruct> &)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "call_server_method", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp_call_server_method, " ::kj::Promise<void>  *(PyObject *, char *,  ::capnp::CallContext< ::capnp::DynamicStruct, ::capnp::DynamicStruct> &)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "wrap_kj_exception", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp_wrap_kj_exception, "PyObject *( ::kj::Exception &)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "wrap_kj_exception_for_reraise", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp_wrap_kj_exception_for_reraise, "PyObject *( ::kj::Exception &)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "get_exception_info", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp_get_exception_info, "PyObject *(PyObject *, PyObject *, PyObject *)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "promise_task_add_done_callback", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp_promise_task_add_done_callback, "void (PyObject *, PyObject *, ::kj::PromiseFulfiller<void> &)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "promise_task_cancel", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp_promise_task_cancel, "void (PyObject *)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "_asyncio_stream_write_start", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_write_start, "void (PyObject *,  ::kj::ArrayPtr< ::kj::ArrayPtr<uint8_t const >  const > , ::kj::PromiseFulfiller<void> &)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "_asyncio_stream_write_stop", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_write_stop, "void (PyObject *)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "_asyncio_stream_read_start", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_read_start, "void (PyObject *, void *, size_t, size_t,  ::kj::PromiseFulfiller<size_t>  &)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "_asyncio_stream_read_stop", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_read_stop, "void (PyObject *)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "_asyncio_stream_shutdown_write", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_shutdown_write, "void (PyObject *)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "_asyncio_stream_close", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp__asyncio_stream_close, "void (PyObject *)") < 0) goto bad;
+  if (__Pyx_ImportFunction_0_29_36(module, "make_async_message_reader", (void (**)(void))&__pyx_api_f_5capnp_3lib_5capnp_make_async_message_reader, "PyObject *( ::kj::Own< ::capnp::MessageReader> )") < 0) goto bad;
+  Py_DECREF(module); module = 0;
+  return 0;
+  bad:
+  Py_XDECREF(module);
+  return -1;
+}
+
+#endif /* !__PYX_HAVE_API__capnp__lib__capnp */
diff --git a/docs/install.rst b/docs/install.rst
@@ -15,16 +15,16 @@ To force rebuilding the pip package from source (you'll need requirments.txt or
 
 To force bundling libcapnp (or force system libcapnp), just in case setup.py isn't doing the right thing::
 
-    pip install --no-binary :all: --install-option "--force-bundled-libcapnp"
-    pip install --no-binary :all: --install-option "--force-system-libcapnp"
+    pip install --no-binary :all: -C force-bundled-libcapnp=True
+    pip install --no-binary :all: -C force-system-libcapnp=True
 
 If you're using an older Linux distro (e.g. CentOS 6) you many need to set `LDFLAGS="-Wl,--no-as-needed -lrt"`::
 
     LDFLAGS="-Wl,--no-as-needed -lrt" pip install --no-binary :all: pycapnp
 
 It's also possible to specify the libcapnp url when bundling (this may not work, there be dragons)::
 
-    pip install --no-binary :all: --install-option "--force-bundled-libcapnp" --install-option "--libcapnp-url" --install-option "https://github.com/capnproto/capnproto/archive/master.tar.gz"
+    pip install --no-binary :all: -C force-bundled-libcapnp=True -C libcapnp-url="https://github.com/capnproto/capnproto/archive/master.tar.gz"
 
 From Source
 -----------

diff --git a/pyproject.toml b/pyproject.toml
@@ -1,5 +1,7 @@
 [build-system]
 requires = ["setuptools", "wheel", "pkgconfig", "cython<3"]
+build-backend = "backend"
+backend-path = ["_custom_build"]
 
 [tool.pytest.ini_options]
 asyncio_mode = "auto"
diff --git a/setup.cfg b/setup.cfg
@@ -1,3 +1,3 @@
 [metadata]
-description-file = README.md
+description_file = README.md
 license_files = LICENSE.md
diff --git a/setup.py b/setup.py
@@ -15,10 +15,12 @@
 
 from setuptools import setup, Extension
 
+_this_dir = os.path.dirname(__file__)
+sys.path.insert(1, _this_dir)
+
 from buildutils.build import build_libcapnp
 from buildutils.bundle import fetch_libcapnp
 
-_this_dir = os.path.dirname(__file__)
 
 MAJOR = 1
 MINOR = 3
@@ -85,26 +87,6 @@ def run(self):
                 shutil.rmtree(x, ignore_errors=True)
 
 
-# hack to parse commandline arguments
-force_bundled_libcapnp = "--force-bundled-libcapnp" in sys.argv
-if force_bundled_libcapnp:
-    sys.argv.remove("--force-bundled-libcapnp")
-force_system_libcapnp = "--force-system-libcapnp" in sys.argv
-if force_system_libcapnp:
-    sys.argv.remove("--force-system-libcapnp")
-force_cython = "--force-cython" in sys.argv
-if force_cython:
-    sys.argv.remove("--force-cython")
-    # Always use cython, ignoring option
-libcapnp_url = None
-try:
-    libcapnp_url_index = sys.argv.index("--libcapnp-url")
-    libcapnp_url = sys.argv[libcapnp_url_index + 1]
-    sys.argv.remove("--libcapnp-url")
-    sys.argv.remove(libcapnp_url)
-except Exception:
-    pass
-
 from Cython.Distutils import build_ext as build_ext_c  # noqa: E402
 
 
@@ -113,13 +95,29 @@ class build_libcapnp_ext(build_ext_c):
     Build capnproto library
     """
 
+    user_options = build_ext_c.user_options + [
+        ("force-bundled-libcapnp", None, "Bundle capnp library into the installer"),
+        ("force-system-libcapnp", None, "Use system capnp library"),
+        ("libcapnp-url=", "u", "URL to download libcapnp from (only if bundled)"),
+    ]
+
+    def initialize_options(self):
+        build_ext_c.initialize_options(self)
+        self.force_bundled_libcapnp = None
+        self.force_system_libcapnp = None
+        self.libcapnp_url = None
+
+    def finalize_options(self):
+        # print('The custom option for install is ', self.custom_option)
+        build_ext_c.finalize_options(self)
+
     def build_extension(self, ext):
         build_ext_c.build_extension(self, ext)
 
     def run(self):  # noqa: C901
-        if force_bundled_libcapnp:
+        if self.force_bundled_libcapnp:
             need_build = True
-        elif force_system_libcapnp:
+        elif self.force_system_libcapnp:
             need_build = False
         else:
             # Try to use capnp executable to find include and lib path
@@ -167,7 +165,7 @@ def run(self):  # noqa: C901
 
             if not os.path.exists(capnp_bin):
                 # Not built, fetch and build
-                fetch_libcapnp(bundle_dir, libcapnp_url)
+                fetch_libcapnp(bundle_dir, self.libcapnp_url)
                 build_libcapnp(bundle_dir, build_dir)
             else:
                 print("capnproto already built at {}".format(build_dir))

diff --git a/tox.ini b/tox.ini
@@ -7,10 +7,11 @@ deps=
     pkgconfig
     Jinja2
     pytest
+    pytest-asyncio
     cython<3
 
 commands =
-    python setup.py install
+    pip install .
     py.test {posargs}
 
 setenv =