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| <TITLE>Creating standalone applications with Python</TITLE> |
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| <H1>Creating standalone applications with Python</H1> |
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| With the <EM>macfreeze</EM> script you can <i>freeze</i> a Python |
| script: create a fullblown Macintosh application that is completely |
| self-contained. A frozen application is similar to an applet (see <a |
| href="example2.html">Example 2</a> for information on creating applets), |
| but where an applet depends on an existing Python installation for its |
| standard modules and interpreter core, a frozen program does not, |
| because it incorporates everything in a single binary. This means you |
| can copy a frozen program to a machine that does not have Python |
| installed and it will work, which is not true for an applet. <p> |
| |
| There are two ways to create a frozen application: through the |
| CodeWarrior development environment or without any development |
| environment. The former method is more versatile and may result in |
| smaller binaries, because you can better customize what is included in |
| your eventual application. The latter method builds an application by |
| glueing together the various <em>.slb</em> shared libraries that come |
| with a binary Python installation into a single file. This method of |
| freezing, which does not require you to spend money on a development |
| environment, is unique to MacPython, incidentally, on other platforms |
| you will always need a C compiler and linker. <p> |
| |
| <h2>Common steps</h2> |
| |
| The two processes have a number of steps in common. When you start |
| <code>Mac:Tools:macfreeze:macfreeze.py</code> you are asked for the |
| script file, and you can select which type of freeze to do. The first |
| time you should always choose <em>report only</em>, which will produce a |
| listing of modules and where they are included from in the console |
| window. Macfreeze actually parses all modules, so it may crash in the |
| process. If it does try again with a higher debug value, this should |
| show you where it crashes. <p> |
| |
| For more elaborate programs you will often see that freeze includes |
| modules you don't need (because they are for a different platform, for |
| instance) or that it cannot find all your modules (because you modify |
| <code>sys.path</code> early in your initialization). It is possible to |
| include directives to tell macfreeze to add items to the search path and |
| include or exclude certain modules. All your directives should be in the |
| main script file. <p> |
| |
| Directives have the following form: |
| <pre> |
| # macfreeze: command argument |
| </pre> |
| The trigger <code>macfreeze:</code> must be spelled exactly like that, |
| but the whitespace can be any combination of spaces and tabs. Macfreeze |
| understands the following directives: |
| |
| <DL> |
| <DT> <code>path</code> |
| <DD> Prepend a folder to <code>sys.path</code>. The argument is a |
| pathname, which should probably be relative (starting with a colon) and |
| is interpreted relative to the folder where the script lives. |
| |
| <DT> <code>include</code> |
| <DD> Include a module. The module can either be given by filename or by |
| module name, in which case it is looked up through the normal method. |
| |
| <DT> <code>exclude</code> |
| <DD> Exclude a module. The module must be given by modulename. Even when |
| freeze deems the module necessary it will not be included in the |
| application. |
| |
| </DL> |
| |
| There is actually a fourth way that macfreeze can operate: it can be used |
| to generate only the resource file containing the compiled <code>PYC</code> |
| resources. This may be useful if you have embedded Python in your own |
| application. The resource file generated is the same as for the CodeWarrior |
| generation process. <p> |
| |
| <h2>Freezing with CodeWarrior</h2> |
| |
| To freeze with CodeWarrior you need CodeWarrior, obviously, and a full |
| source distribution of Python. You select the <em>Codewarrior source and |
| project</em> option. You specify an output folder, which is by default |
| the name of your script with <code>.py</code> removed and |
| <code>build.</code> prepended. If the output folder does not exist yet |
| it is created, and a template project file and bundle resource file are |
| deposited there. Next, a source file <code>macfreezeconfig.c</code> is |
| created which includes all builtin modules your script uses, and a |
| resource file <code>frozenmodules.rsrc</code> which contains the |
| <code>PYC</code> resources for all your Python modules. <p> |
| |
| The project expects to live in a folder one level below the Python root |
| folder, so the next thing you should do is move the build folder there. |
| It is a good idea to leave an alias with the same name in the original |
| location: when you run freeze again it will regenerate the |
| <code>frozenmodules.rsrc</code> file but not the project and bundle |
| files. This is probably what you want: if you modify your python sources |
| you have to re-freeze, but you may have changed the project and bundle |
| files, so you don't want to regenrate them. <p> |
| |
| An alternative is to leave the build folder where it is, but then you |
| have to adapt the search path in the project. <p> |
| |
| The project is set up to include all the standard builtin modules, but |
| the CW linker is smart enough to exclude any object code that isn't |
| referenced. Still, it may be worthwhile to remove any sources for |
| modules that you are sure are not used to cut back on compilation time. |
| You may also want to examine the various resource files (for Tcl/Tk, for |
| instance): the loader has no way to know that these aren't used. <p> |
| |
| You may also need to add sourcefiles if your script uses non-standard |
| builtin modules, like anything from the <code>Extensions</code> folder. <p> |
| |
| The <code>frozenbundle.rsrc</code> resource file contains the bundle |
| information. It is almost identical to the bundle file used for applets, |
| with the exception that it sets the <code>sys.path</code> initialization |
| to <code>$(APPLICATION)</code> only. This means that all modules will only |
| be looked for in PYC resources in your application. <p> |
| |
| <h2>Freezing without CodeWarrior</h2> |
| |
| This does not work yet. |
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