Author: Armin Rigo <[email protected]>
Branch: doc-set_source
Changeset: r3056:d2fac65c0e82
Date: 2018-01-08 14:55 +0100
http://bitbucket.org/cffi/cffi/changeset/d2fac65c0e82/
Log: More tweaks
diff --git a/doc/source/overview.rst b/doc/source/overview.rst
--- a/doc/source/overview.rst
+++ b/doc/source/overview.rst
@@ -45,8 +45,9 @@
there, %s!\n"``. In general it is ``somestring.encode(myencoding)``.
*Python 3 on Windows:* ``ffi.dlopen(None)`` does not work. This problem
-is messy and not really fixable. The example above could be fixed by
-calling another function from a specific DLL that exists on your system.
+is messy and not really fixable. The problem does not occur if you try
+to call a fucntion from a specific DLL that exists on your system: then
+you use ``ffi.dlopen("path.dll")``.
*This example does not call any C compiler. It works in the so-called
ABI mode, which means that it will crash if you call some function or
@@ -80,8 +81,9 @@
// contains implementation of things declared in cdef()
#include <sys/types.h>
#include <pwd.h>
- struct passwd *mygetpwuid(int uid) {
- return getpwuid(uid);
+
+ struct passwd *get_pw_for_root(void) {
+ return getpwuid(0);
}
""",
libraries=[]) # or a list of libraries to link with
@@ -89,12 +91,13 @@
# include_dirs=[..], extra_objects=[..], and so on)
ffibuilder.cdef("""
- // declarations that are shared between python and C
+ // declarations that are shared between Python and C
struct passwd {
char *pw_name;
...; // literally dot-dot-dot
};
- struct passwd *mygetpwuid(int uid);
+ struct passwd *getpwuid(int uid); // defined in <pwd.h>
+ struct passwd *get_pw_for_root(void); // defined in set_source()
""")
if __name__ == "__main__":
@@ -116,17 +119,20 @@
from _example import ffi, lib
- p = lib.mygetpwuid(0)
+ p = lib.getpwuid(0)
+ assert ffi.string(p.pw_name) == b'root'
+ p = lib.get_pw_for_root()
assert ffi.string(p.pw_name) == b'root'
Note that this works independently of the exact C layout of ``struct
passwd`` (it is "API level", as opposed to "ABI level"). It requires
a C compiler in order to run ``example_build.py``, but it is much more
portable than trying to get the details of the fields of ``struct
-passwd`` exactly right. Similarly, we declared ``mygetpwuid()`` as
-taking an ``int`` argument. On some platforms this might be slightly
-incorrect---but it does not matter. It is also faster than the ABI
-mode.
+passwd`` exactly right. Similarly, in the ``cdef()`` we declared
+``getpwuid()`` as taking an ``int`` argument; on some platforms this
+might be slightly incorrect---but it does not matter.
+
+Note also that at runtime, the API mode is faster than the ABI mode.
To integrate it inside a ``setup.py`` distribution with Setuptools:
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