mirror of https://github.com/python/cpython
109 lines
3.9 KiB
Plaintext
109 lines
3.9 KiB
Plaintext
THE FREEZE SCRIPT
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=================
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What is Freeze?
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---------------
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Freeze make it possible to ship arbitrary Python programs to people
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who don't have Python. The shipped file (called a "frozen" version of
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your Python program) is an executable, so this only works if your
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platform is compatible with that on the receiving end (this is usually
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a matter of having the same major operating system revision and CPU
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type).
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The shipped file contains a Python interpreter and large portions of
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the Python run-time. Some measures have been taken to avoid linking
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unneeded modules, but the resulting binary is usually not small.
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The Python source code of your program (and of the library modules
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written in Python that it uses) is not included in the binary --
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instead, the compiled byte-code (the instruction stream used
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internally by the interpreter) is incorporated. This gives some
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protection of your Python source code, though not much -- a
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disassembler for Python byte-code is available in the standard Python
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library. At least someone running "strings" on your binary won't see
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the source.
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How does Freeze know which modules to include?
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----------------------------------------------
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Freeze uses a pretty simple-minded algorithm to find the modules that
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your program uses: given a file containing Python source code, it
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scans for lines beginning with the word "import" or "from" (possibly
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preceded by whitespace) and then it knows where to find the module
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name(s) in those lines. It then recursively scans the source for
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those modules (if found, and not already processed) in the same way.
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Freeze will not see import statements hidden behind another statement,
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like this:
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if some_test: import M # M not seen
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or like this:
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import A; import B; import C # B and C not seen
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nor will it see import statements constructed using string
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operations and passed to 'exec', like this:
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exec "import %s" % "M" # M not seen
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On the other hand, Freeze will think you are importing a module even
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if the import statement it sees will never be executed, like this:
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if 0:
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import M # M is seen
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One tricky issue: Freeze assumes that the Python interpreter and
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environment you're using to run Freeze is the same one that would be
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used to run your program, which should also be the same whose sources
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and installed files you will learn about in the next section. In
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particular, your PYTHONPATH setting should be the same as for running
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your program locally. (Tip: if the program doesn't run when you type
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"python hello.py" there's little chance of getting the frozen version
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to run.)
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How do I use Freeze?
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--------------------
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Normally, you should be able to use it as follows:
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python freeze.py hello.py
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where hello.py is your program and freeze.py is the main file of
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Freeze (in actuality, you'll probably specify an absolute pathname
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such as /usr/joe/python/Tools/freeze/freeze.py).
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(With Python 1.4, freeze is much more likely to work "out of the box"
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than before, provided Python has been installed properly.)
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What do I do next?
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------------------
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Freeze creates three files: frozen.c, config.c and Makefile. To
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produce the frozen version of your program, you can simply type
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"make". This should produce a binary file. If the filename argument
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to Freeze was "hello.py", the binary will be called "hello".
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Note: you can use the -o option to freeze to specify an alternative
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directory where these files are created. This makes it easier to
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clean up after you've shipped the frozen binary.
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Troubleshooting
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---------------
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If you have trouble using Freeze for a large program, it's probably
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best to start playing with a really simple program first (like the file
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hello.py). If you can't get that to work there's something
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fundamentally wrong -- perhaps you haven't installed Python. To do a
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proper install, you should do "make install" in the Python root
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directory.
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--Guido van Rossum (home page: http://www.python.org/~guido/)
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