python编译py成pyc和pyo

michellc

python编译py成pyc和pyo
　　pyc是一种二进制文件，是由py文件经过编译后，生成的文件，是一种byte code，py文件变成pyc文件后，加载的速度有所提高，而且pyc是一种跨平台的字节码，是由python的虚拟机来执行的，这个是类似于JAVA或 者.NET的虚拟机的概念。pyc的内容，是跟python的版本相关的，不同版本编译后的pyc文件是不同的，2.5编译的pyc文件，2.4版本的 python是无法执行的。
　　1.编译单个py文件
　　(1)
　　直接在命令行下执行 python -m py_compile file.py
　　(2)
　　在python代码中使用py_compile.compile函数来编译。该函数的帮助信息如下：

Help on function compile in module py_compile:
compile(file, cfile=None, dfile=None, doraise=False)
Byte-compile one Python source file to Python bytecode.
Arguments:
file:    source filename
cfile:   target filename; defaults to source with 'c' or 'o' appended
('c' normally, 'o' in optimizing mode, giving .pyc or .pyo)
dfile:   purported filename; defaults to source (this is the filename
that will show up in error messages)
doraise: flag indicating whether or not an exception should be
raised when a compile error is found. If an exception
occurs and this flag is set to False, a string
indicating the nature of the exception will be printed,
and the function will return to the caller. If an
exception occurs and this flag is set to True, a
PyCompileError exception will be raised.
Note that it isn't necessary to byte-compile Python modules for
execution efficiency -- Python itself byte-compiles a module when
it is loaded, and if it can, writes out the bytecode to the
corresponding .pyc (or .pyo) file.
However, if a Python installation is shared between users, it is a
good idea to byte-compile all modules upon installation, since
other users may not be able to write in the source directories,
and thus they won't be able to write the .pyc/.pyo file, and then
they would be byte-compiling every module each time it is loaded.
This can slow down program start-up considerably.
See compileall.py for a script/module that uses this module to
byte-compile all installed files (or all files in selected
directories).
 
[baichuan@zjdw-odmz-0009 python]$ ls
adp_group_info_data  adp_group_info.py  db_api.py  db_api.pyc  dump_rmc_area_ip.py  dump_rmc_tag.py
[baichuan@zjdw-odmz-0009 python]$ python
Python 2.6.6 (r266:84292, Jan 22 2014, 09:42:36)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import py_compile
>>> py_compile.compile("adp_group_info.py")
>>> py_compile.compile("/home/baichuan/yxc/python/dump_rmc_tag.py")
>>> quit()
[baichuan@zjdw-odmz-0009 python]$ ls
adp_group_info_data  adp_group_info.py  adp_group_info.pyc  db_api.py  db_api.pyc  dump_rmc_area_ip.py  dump_rmc_tag.py  dump_rmc_tag.pyc
[baichuan@zjdw-odmz-0009 python]$

 
　　2.批量生成pyc文件
　　在python代码中使用compileall.compile_dir函数来编译。该函数的帮助信息如下：

Help on function compile_dir in module compileall:
compile_dir(dir, maxlevels=10, ddir=None, force=0, rx=None, quiet=0)
Byte-compile all modules in the given directory tree.
Arguments (only dir is required):
dir:       the directory to byte-compile
maxlevels: maximum recursion level (default 10)
ddir:      if given, purported directory name (this is the
directory name that will show up in error messages)
force:     if 1, force compilation, even if timestamps are up-to-date
quiet:     if 1, be quiet during compilation
[baichuan@zjdw-odmz-0009 python]$ ls
adp_group_info_data  adp_group_info.py  db_api.py  dump_rmc_area_ip.py  dump_rmc_tag.py
[baichuan@zjdw-odmz-0009 python]$ python
Python 2.6.6 (r266:84292, Jan 22 2014, 09:42:36)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import compileall
>>> compileall.compile_dir("/home/baichuan/yxc/python/")
Listing /home/baichuan/yxc/python/ ...
Compiling /home/baichuan/yxc/python/adp_group_info.py ...
Compiling /home/baichuan/yxc/python/db_api.py ...
Compiling /home/baichuan/yxc/python/dump_rmc_area_ip.py ...
Compiling /home/baichuan/yxc/python/dump_rmc_tag.py ...
1
>>> quit()
[baichuan@zjdw-odmz-0009 python]$ ls
adp_group_info_data  adp_group_info.py  adp_group_info.pyc  db_api.py  db_api.pyc  dump_rmc_area_ip.py  dump_rmc_area_ip.pyc  dump_rmc_tag.py  dump_rmc_tag.pyc
[baichuan@zjdw-odmz-0009 python]$