THE FREEZE SCRIPT ================= (Directions for Windows are at the end of this file.) What is Freeze? --------------- Freeze make it possible to ship arbitrary Python programs to people who don't have Python. The shipped file (called a "frozen" version of your Python program) is an executable, so this only works if your platform is compatible with that on the receiving end (this is usually a matter of having the same major operating system revision and CPU type). The shipped file contains a Python interpreter and large portions of the Python run-time. Some measures have been taken to avoid linking unneeded modules, but the resulting binary is usually not small. The Python source code of your program (and of the library modules written in Python that it uses) is not included in the binary -- instead, the compiled byte-code (the instruction stream used internally by the interpreter) is incorporated. This gives some protection of your Python source code, though not much -- a disassembler for Python byte-code is available in the standard Python library. At least someone running "strings" on your binary won't see the source. How does Freeze know which modules to include? ---------------------------------------------- Previous versions of Freeze used a pretty simple-minded algorithm to find the modules that your program uses, essentially searching for lines starting with the word "import". It was pretty easy to trick it into making mistakes, either missing valid import statements, or mistaking string literals (e.g. doc strings) for import statements. This has been remedied: Freeze now uses the regular Python parser to parse the program (and all its modules) and scans the generated byte code for IMPORT instructions. It may still be confused -- it will not know about calls to the __import__ built-in function, or about import statements constructed on the fly and executed using the 'exec' statement, and it will consider import statements even when they are unreachable (e.g. "if 0: import foobar"). This new version of Freeze also knows about Python's new package import mechanism, and uses exactly the same rules to find imported modules and packages. One exception: if you write 'from package import *', Python will look into the __all__ variable of the package to determine which modules are to be imported, while Freeze will do a directory listing. One tricky issue: Freeze assumes that the Python interpreter and environment you're using to run Freeze is the same one that would be used to run your program, which should also be the same whose sources and installed files you will learn about in the next section. In particular, your PYTHONPATH setting should be the same as for running your program locally. (Tip: if the program doesn't run when you type "python hello.py" there's little chance of getting the frozen version to run.) How do I use Freeze? -------------------- Normally, you should be able to use it as follows: python freeze.py hello.py where hello.py is your program and freeze.py is the main file of Freeze (in actuality, you'll probably specify an absolute pathname such as /usr/joe/python/Tools/freeze/freeze.py). What do I do next? ------------------ Freeze creates a number of files: frozen.c, config.c and Makefile, plus one file for each Python module that gets included named M_.c. To produce the frozen version of your program, you can simply type "make". This should produce a binary file. If the filename argument to Freeze was "hello.py", the binary will be called "hello". Note: you can use the -o option to freeze to specify an alternative directory where these files are created. This makes it easier to clean up after you've shipped the frozen binary. You should invoke "make" in the given directory. Freezing Tkinter programs ------------------------- Unfortunately, it is currently not possible to freeze programs that use Tkinter. It *seems* to work, but when you ship the frozen program to a site without a Tcl/Tk installation, it will fail with a complaint about missing Tcl/Tk initialization files. A workaround would be possible, in which the Tcl/Tk library files are incorporated in a frozen Python module as string literals and written to a temporary location when the program runs; this is currently left as an exercise for the reader. (If you implement this, please post to the Python newsgroup!) Of course, you can also simply require that Tcl/Tk is required on the target installation. A warning against shared library modules ---------------------------------------- When your Python installation uses shared library modules, these will not be incorporated in the frozen program. Again, the frozen program will work when you test it, but it won't work when you ship it to a site without a Python installation. Freeze prints a warning when this is the case at the end of the freezing process: Warning: unknown modules remain: ... When this occurs, the best thing to do is usually to rebuild Python using static linking only. Troubleshooting --------------- If you have trouble using Freeze for a large program, it's probably best to start playing with a really simple program first (like the file hello.py). If you can't get that to work there's something fundamentally wrong -- perhaps you haven't installed Python. To do a proper install, you should do "make install" in the Python root directory. Usage under Windows 95 or NT ---------------------------- Under Windows 95 or NT, you *must* use the -p option and point it to the top of the Python source tree. WARNING: the resulting executable is not self-contained; it requires the Python DLL, currently PYTHON15.DLL (it does not require the standard library of .py files though). It may also require one or more extension modules loaded from .DLL or .PYD files; the module names are printed in the warning message about remaining unknown modules. The driver script generates a Makefile that works with the Microsoft command line C compiler (CL). To compile, run "nmake"; this will build a target "hello.exe" if the source was "hello.py". Only the files frozenmain.c and frozen.c are used; no config.c is generated or used, since the standard DLL is used. In order for this to work, you must have built Python using the VC++ (Developer Studio) 5.0 compiler. The provided project builds python15.lib in the subdirectory pcbuild\Release of thje Python source tree, and this is where the generated Makefile expects it to be. If this is not the case, you can edit the Makefile or (probably better) winmakemakefile.py (e.g., if you are using the 4.2 compiler, the python15.lib file is generated in the subdirectory vc40 of the Python source tree). You can freeze programs that use Tkinter, but Tcl/Tk must be installed on the target system. It is possible to create frozen programs that don't have a console window, by specifying the option '-s windows'. --Guido van Rossum (home page: http://www.python.org/~guido/)