[PATCH 1 of 7] util: add a macro initializing CPython modules

[Jun Wu]

# HG changeset patch
# User Jun Wu <quark at fb.com>
# Date 1494288921 25200
#      Mon May 08 17:15:21 2017 -0700
# Node ID a2c5e183cafca6d58a0dd986870ac620be1fb107
# Parent  52ec3072fe46bc4b193b6273357e3cc40b4421ad
# Available At https://bitbucket.org/quark-zju/hg-draft
#              hg pull https://bitbucket.org/quark-zju/hg-draft -r a2c5e183cafc
util: add a macro initializing CPython modules

This will greatly simplify C module initialization code. The signature
requires a "version" field to help detect incompatible ".so" modules usually
caused by forgetting to build.

diff --git a/mercurial/util.h b/mercurial/util.h
--- a/mercurial/util.h
+++ b/mercurial/util.h
@@ -43,3 +43,43 @@ typedef unsigned char bool;
 #endif
 
+#ifdef IS_PY3K
+#define PYMODULEINIT(name, methods, doc, version, precheck, postinit) \
+	static struct PyModuleDef  name ## _module = { \
+		PyModuleDef_HEAD_INIT, \
+		#name, \
+		doc, \
+		-1, \
+		methods \
+	}; \
+	PyMODINIT_FUNC PyInit_ ## name(void) \
+	{ \
+		PyObject *m; \
+		if (precheck && ((int (*)(void))precheck)() == -1) \
+			return NULL; \
+		m = PyModule_Create(&(name ## _module)); \
+		if (m == NULL) \
+			return NULL; \
+		if (PyModule_AddIntConstant(m, "version", version) == -1) \
+			return NULL; \
+		if (postinit && ((int (*)(PyObject *))postinit)(m) == -1) \
+			return NULL; \
+		return m; \
+	}
+#else
+#define PYMODULEINIT(name, methods, doc, version, precheck, postinit) \
+	PyMODINIT_FUNC (init ## name)(void) \
+	{ \
+		PyObject *m; \
+		if (precheck && ((int (*)(void))precheck)() == -1) \
+			return; \
+		m = Py_InitModule3(#name, methods, doc); \
+		if (m == NULL) \
+			return; \
+		if (PyModule_AddIntConstant(m, "version", version) == -1) \
+			return; \
+		if (postinit != NULL) \
+			((int (*)(PyObject *))postinit)(m); \
+	}
+#endif
+
 #endif /* _HG_UTIL_H_ */