컴파일이 되었으므로, pyc나 pyo는 py에 비해 속도 향상이 있으며
pyc는 py를 -O 옵션을 통해(모든 py파일에서 pyc를 생성)
pyo는 py를 -OO 옵션을 통해 생성이 가능하다.
(이부분은 확인필요. py 파일을 이상없이 실행가능하면 컴파일 가능하며, 자동으로 pyc가 생성된다고 하지만, 밑에
-O 옵션으로 디렉토리 내의 모든 py를 pyc로 컴파일 한다는 내용도 존재한다.)
pyc는 assert 문만을 삭제함으로 속도 향상폭은 크지 않으며
pyo는 pyc에 비해 __doc__ 구분도 삭제하므로 더욱 작이진다.(일부 프로그램은 __doc__ 구분 사용할수 있으니 주의)
6.1.3. “Compiled” Python files
As an important speed-up of the start-up time for short programs that use a lot
of standard modules, if a file called spam.pyc exists in the directory
where spam.py is found, this is assumed to contain an
already-“byte-compiled” version of the module spam. The modification time
of the version of spam.py used to create spam.pyc is recorded in
spam.pyc, and the .pyc file is ignored if these don’t match.
Normally, you don’t need to do anything to create the spam.pyc file.
Whenever spam.py is successfully compiled, an attempt is made to write
the compiled version to spam.pyc. It is not an error if this attempt
fails; if for any reason the file is not written completely, the resulting
spam.pyc file will be recognized as invalid and thus ignored later. The
contents of the spam.pyc file are platform independent, so a Python
module directory can be shared by machines of different architectures.
Some tips for experts:
When the Python interpreter is invoked with the -O flag, optimized
code is generated and stored in .pyo files. The optimizer currently
doesn’t help much; it only removes assert statements. When
-O is used, allbytecode is optimized; .pyc files are
ignored and .py files are compiled to optimized bytecode.
Passing two -O flags to the Python interpreter (-OO) will
cause the bytecode compiler to perform optimizations that could in some rare
cases result in malfunctioning programs. Currently only __doc__ strings are
removed from the bytecode, resulting in more compact .pyo files. Since
some programs may rely on having these available, you should only use this
option if you know what you’re doing.
A program doesn’t run any faster when it is read from a .pyc or
.pyo file than when it is read from a .py file; the only thing
that’s faster about .pyc or .pyo files is the speed with which
they are loaded.
When a script is run by giving its name on the command line, the bytecode for
the script is never written to a .pyc or .pyo file. Thus, thet
startup time of a scrip may be reduced by moving most of its code to a module
and having a small bootstrap script that imports that module. It is also
possible to name a .pyc or .pyo file directly on the command
line.
It is possible to have a file called spam.pyc (or spam.pyo
when -O is used) without a file spam.pyfor the same module.
This can be used to distribute a library of Python code in a form that is
moderately hard to reverse engineer.
The module compileall can create .pyc files (or .pyo
files when -O is used) for all modules in a directory.
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