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Diffstat (limited to 'Mac/USING')
| -rw-r--r-- | Mac/USING | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/Mac/USING b/Mac/USING new file mode 100644 index 0000000..3c67fb7 --- /dev/null +++ b/Mac/USING @@ -0,0 +1,131 @@ +PYTHON RELEASE NOTES FOR THE MACINTOSH + +VERSION 1.0.2 + +For the most part, Python on the Mac works just like Python under UNIX. +The most important differences are: + +- Since there is no shell environment on the Mac, the start-up file + has a fixed name: PythonStartup. If a file by this name exists + (either in the current folder or in the system folder) it is executed + when an interactive interpreter is started. + +- The default search path for modules is different: first the current + directory is searched, then the subdirectories 'lib', 'lib:stdwin' and + 'demo'. As always, you can change this (e.g. in your PythonStartup + file) by assigning or appending to sys.path -- use Macintosh pathnames! + (The default contains no absolute paths because these are unlikely + to make sense on other people's hard disks.) + +- The user interface for typing interactive commands is different. + This is actually the THINK C console I/O module, which is based on + the Mac toolbox TextEdit. A standard Edit menu provides Cut, Copy, + Paste and Clear (Undo is only there for Desk Accessories). A minimal + File menu provides Quit, which immediately exits the application, + without the usual cleanup. You can Copy from previous output, + but you can't scroll back beyond the 24x80 screen. The TAB key + always brings you to the end of the current input line; indentation + must be entered with spaces (a single space is enough). + End-of-file is generated by Command-D; Command-Period interrupts. + There is an annoying limit in the length of an input line to a single + screen line (less the prompt). Use \ to input long statements. + Change your program if it requires long lines typed on input. + Even though there is no resize box, the window can be resized by + dragging its bottom right corner, but the maximum size is 24x80. + +- Tabs in module files are interpreted as 4 (four!) spaces. This is + consistent with most Mac editors that I know. For individual files + you can change the tab size with a comment like + + # vi:set tabsize=8: + + (exactly as shown here, including the colons!). If you are consistent + in always using tabs for indentation on UNIX, your files will be + parsed correctly on the Mac, although they may look funny if you + have nicely lined-up comments or tables using tabs. Never using tabs + also works. Mixing tabs and spaces to simulate 4-character indentation + levels is likely to fail. + +- You can start a script from the Finder by selecting the script and + the Python interpreter together and then double clicking. If you + make the owner of the script PYTH (the type should always be TEXT) + Python will be launched if you double click it! + There is no way to pass command line arguments to Python scripts. + +- The set of built-in modules is different: + + = Operating system functions for the 'os' module is provided by the + built-in module 'mac', not 'posix'. This doesn't have all the + functions from posix, for obvious reasons (if you know the Mac + O/S a little bit). The functions in os.path are provided by + macpath, they know about Mac pathnames etc. + + = None of the UNIX specific modules ('socket', 'pwd', 'grp' etc.) + exists. + + = Module 'stdwin' is always available. It uses the Mac version of + STDWIN, which interfaces directly with the Mac toolbox. The most + important difference is in the font names; setfont() has a second + argument specifying the point size and an optional third one + specifying the variation: a single letter character string, + 'i' for italics, 'b' for bold. Note that when STDWIN is waiting + for events, the standard File and Edit menus are inactive but + still visible, and (most annoyingly) the Apple menu is also inactive; + conversely, menus put up by STDWIN are not active when the Python is + reading from the keyboard. If you open Python together with a text + file containing a Python script, the script will be executed and + a console window is only generated when the script uses standard + input or output. A script that uses STDWIN exclusively for its I/O + will have a working Apple menu and no extraneous File/Edit menus. + (This is because both stdwin and stdio try to initialize the + windowing environment; whoever gets there first owns the Apple menu.) + LIMITATIONS: a few recent additions to STDWIN for X11 have not yet + been added to the Mac version. There are no bitmap objects, and + the setwinpos() and setwinsize() methods are non--functional. + +- Because launching an application on the Mac is so tedious, you will + want to edit your program with a desk accessory editor (e.g., Sigma + edit) and test the changed version without leaving Python. This is + possible but requires some care. Make sure the program is a module + file (filename must be a Python identifier followed by '.py'). You + can then import it when you test it for the first time. There are + now three possibilities: it contains a syntax error; it gets a runtime + error (unhandled exception); or it runs OK but gives wrong results. + (If it gives correct results, you are done testing and don't need + to read the rest of this paragraph. :-) Note that the following + is not Mac-specific -- it's just that on UNIX it's easier to restart + the entire script so it's rarely useful. + + Recovery from a syntax error is easy: edit the file and import it + again. + + Recovery from wrong output is almost as easy: edit the file and, + instead of importing it, call the function reload() with the module + name as argument (e.g., if your module is called foo, type + "reload(foo)"). + + Recovery from an exception is trickier. Once the syntax is correct, + a 'module' entry is placed in an internal table, and following import + statements will not re-read the file, even if the module's initialization + terminated with an error (one reason why this is done is so that + mutually recursive modules are initialized only once). You must + therefore force re-reading the module with reload(), however, if this + happens the first time you try to import the module, the import statement + itself has not completed, and your workspace does not know the module + name (even though the internal table of moduesl does!). The trick is + to first import the module again, then reload it. For instance, + "import foo; reload(foo)". Because the module object already exists + internally, the import statement does not attempt to execute the + module again -- it just places it in your workspace. + + When you edit a module you don't have to worry about the corresponding + '.pyc' file (a "compiled" version of the module, which loads much faster + than the textual version): the interpreter notices that the '.py' file + has changed (because its modification time has changed) and ignores the + '.pyc' file. When parsing is successful, a new '.pyc' file is written; + if this fails (no write permission, disk full or whatever) it is + silently skipped but attempted again the next time the same module + is loaded. (Thus, if you plan to place a Python library on a read-only + disk, it is advisable to "warm the cache" by making the disk writable + and importing all modules once. The standard module 'importall' helps + in doing this.) |