This is a basic guide to try cppyy and see whether it works for you. Large code bases will benefit from more advanced features such as pythonizations for a cleaner interface to clients; precompiled modules for faster parsing and reduced memory usage; “ dictionaries ” to package locations and manage dependencies; and mapping files for automatic, lazy, loading. You can, however, get very far with just the basics and it may even be completely sufficient for small packages with fewer classes.
cppyy works by parsing C++ definitions through
cling
, generating tiny wrapper codes to honor compile-time features and create standardized interfaces, then compiling/linking those wrappers with the
clang
JIT. It thus requires only those two ingredients:
C++ 定义
and
链接器符号
. All cppyy uses, the basic and the more advanced, are variations on the theme of bringing these two together at the point of use.
Definitions typically live in header files and symbols in libraries. Headers can be loaded with
cppyy.include
and libraries with the
cppyy.load_library
call. Loading the header is sufficient to start exploring, with
cppyy.gbl
the starting point of all things C++, while the linker symbols are only needed at the point of first use.
这里的范例是使用 zlib library, which is likely available on your system:
>>> import cppyy >>> cppyy.include('zlib.h') # bring in C++ definitions >>> cppyy.load_library('libz') # load linker symbols >>> cppyy.gbl.zlibVersion() # use a zlib API '1.2.11' >>>
Since header files can include other header files, it is easy to aggregate all relevant ones into a single header to include. If there are project-specific include paths, you can add those paths through
cppyy.add_include_path
. If a header is C-only and not set for use with C++, use
cppyy.c_include
, which adds
extern "C"
around the header.
Library files can be aggregated by linking all relevant ones to a single library to load. Using the linker for this purpose allows regular system features such as
rpath
and envars such as
LD_LIBRARY_PATH
to be applied as usual. Note that any mechanism that exposes the library symbols will work. For example, you could also use the standard module
ctypes
through
ctypes.CDLL
采用
ctypes.RTLD_GLOBAL
选项。
To explore, start from
cppyy.gbl
to access your namespaces, classes, functions, etc., etc. directly; or use python’s
dir
(or tab-completion) to see what is available. Use python’s
help
to see list the methods and data members of classes and see the interfaces of functions.
Now try this out for some of your own headers, libraries, and APIs!
