cpython/Tools/freeze

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_<module>.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 without a Tcl/Tk installation. The best way to ship a
frozen Tkinter program is to decide in advance where you are going
to place the Tcl and Tk library files in the distributed setup, and
then declare these directories in your frozen Python program using
the TCL_LIBRARY and TK_LIBRARY environment variables.

For example, assume you will ship your frozen program in the directory
<root>/bin/windows-x86 and will place your Tcl library files
in <root>/lib/tcl8.2 and your Tk library files in <root>/lib/tk8.2. Then
placing the following lines in your frozen Python script before importing
tkinter would set the environment correctly for Tcl/Tk:

import os
import os.path
RootDir = os.path.dirname(os.path.dirname(os.getcwd()))

import sys
if sys.platform == "win32":
   sys.path = ['', '..\\..\\lib\\python-2.0']
   os.environ['TCL_LIBRARY'] = RootDir + '\\lib\\tcl8.2'
   os.environ['TK_LIBRARY'] = RootDir + '\\lib\\tk8.2'
elif sys.platform == "linux2":
   sys.path = ['', '../../lib/python-2.0']
   os.environ['TCL_LIBRARY'] = RootDir + '/lib/tcl8.2'
   os.environ['TK_LIBRARY'] = RootDir + '/lib/tk8.2'
elif sys.platform == "solaris":
   sys.path = ['', '../../lib/python-2.0']
   os.environ['TCL_LIBRARY'] = RootDir + '/lib/tcl8.2'
   os.environ['TK_LIBRARY'] = RootDir + '/lib/tk8.2'

This also adds <root>/lib/python-2.0 to your Python path
for any Python files such as _tkinter.pyd you may need.

Note that the dynamic libraries (such as tcl82.dll tk82.dll python20.dll
under Windows, or libtcl8.2.so and libtcl8.2.so under Unix) are required
at program load time, and are searched by the operating system loader
before Python can be started. Under Windows, the environment
variable PATH is consulted, and under Unix, it may be the
environment variable LD_LIBRARY_PATH and/or the system
shared library cache (ld.so). An additional preferred directory for
finding the dynamic libraries is built into the .dll or .so files at
compile time - see the LIB_RUNTIME_DIR variable in the Tcl makefile.
The OS must find the dynamic libraries or your frozen program won't start.
Usually I make sure that the .so or .dll files are in the same directory
as the executable, but this may not be foolproof.

A workaround to installing your Tcl library files with your frozen
executable 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.  An easier approach is to freeze the
Tcl/Tk code into the dynamic libraries using the Tcl ET code.
Of course, you can also simply require that Tcl/Tk is required on the
target installation, but be careful that the version corresponds.

There are some caveats using frozen Tkinter applications:
	Under Windows if you use the -s windows option, writing
to stdout or stderr is an error.
	The Tcl [info nameofexecutable] will be set to where the
program was frozen, not where it is run from.
	The global variables argc and argv do not exist.


A warning about shared library modules
--------------------------------------

When your Python installation uses shared library modules such as
_tkinter.pyd, 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. Or use the approach described in the previous
section to declare a library path using sys.path, and place the modules
such as _tkinter.pyd there.


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 PYTHON20.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
python20.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
python20.lib file is generated in the subdirectory vc40 of the Python
source tree).

It is possible to create frozen programs that don't have a console
window, by specifying the option '-s windows'. See the Usage below.

Usage under macOS
-----------------

On macOS the freeze tool is not supported for framework builds.

Usage
-----

Here is a list of all of the options (taken from freeze.__doc__):

usage: freeze [options...] script [module]...

Options:
-p prefix:    This is the prefix used when you ran ``make install''
              in the Python build directory.
              (If you never ran this, freeze won't work.)
              The default is whatever sys.prefix evaluates to.
              It can also be the top directory of the Python source
              tree; then -P must point to the build tree.

-P exec_prefix: Like -p but this is the 'exec_prefix', used to
                install objects etc.  The default is whatever sys.exec_prefix
                evaluates to, or the -p argument if given.
                If -p points to the Python source tree, -P must point
                to the build tree, if different.

-e extension: A directory containing additional .o files that
              may be used to resolve modules.  This directory
              should also have a Setup file describing the .o files.
              On Windows, the name of a .INI file describing one
              or more extensions is passed.
              More than one -e option may be given.

-o dir:       Directory where the output files are created; default '.'.

-m:           Additional arguments are module names instead of filenames.

-a package=dir: Additional directories to be added to the package's
                __path__.  Used to simulate directories added by the
                package at runtime (eg, by OpenGL and win32com).
                More than one -a option may be given for each package.

-l file:      Pass the file to the linker (windows only)

-d:           Debugging mode for the module finder.

-q:           Make the module finder totally quiet.

-h:           Print this help message.

-x module     Exclude the specified module.

-i filename:  Include a file with additional command line options.  Used
              to prevent command lines growing beyond the capabilities of
              the shell/OS.  All arguments specified in filename
              are read and the -i option replaced with the parsed
              params (note - quoting args in this file is NOT supported)

-s subsystem: Specify the subsystem (For Windows only.);
              'console' (default), 'windows', 'service' or 'com_dll'

-w:           Toggle Windows (NT or 95) behavior.
              (For debugging only -- on a win32 platform, win32 behavior
              is automatic.)

Arguments:

script:       The Python script to be executed by the resulting binary.

module ...:   Additional Python modules (referenced by pathname)
              that will be included in the resulting binary.  These
              may be .py or .pyc files.  If -m is specified, these are
              module names that are search in the path instead.



--Guido van Rossum (home page: https://www.python.org/~guido/)