From: Senthil Kumaran Date: Thu, 18 Sep 2014 13:37:26 +0000 (+0800) Subject: merge from 3.4 X-Git-Tag: v3.5.0a1~901 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2f2920a17f1b51f9536e5d4c8a9b557558c4a07a;p=python merge from 3.4 Issue #16827: Make Interpreter introduction section of the tutorial more focussed and move advanced section and customization information to a separate file called appendix. Patch credits: Jamayla Wiley, Ya-Ting Huang and James Brewer. --- 2f2920a17f1b51f9536e5d4c8a9b557558c4a07a diff --cc Doc/tutorial/appendix.rst index 0000000000,8670efc8e9..67262a1d80 mode 000000,100644..100644 --- a/Doc/tutorial/appendix.rst +++ b/Doc/tutorial/appendix.rst @@@ -1,0 -1,124 +1,124 @@@ + .. _tut-appendix: + + ******** + Appendix + ******** + + + .. _tut-interac: + + Interactive Mode + ================ + + .. _tut-error: + + Error Handling + -------------- + + When an error occurs, the interpreter prints an error message and a stack trace. + In interactive mode, it then returns to the primary prompt; when input came from + a file, it exits with a nonzero exit status after printing the stack trace. + (Exceptions handled by an :keyword:`except` clause in a :keyword:`try` statement + are not errors in this context.) Some errors are unconditionally fatal and + cause an exit with a nonzero exit; this applies to internal inconsistencies and + some cases of running out of memory. All error messages are written to the + standard error stream; normal output from executed commands is written to + standard output. + + Typing the interrupt character (usually Control-C or DEL) to the primary or + secondary prompt cancels the input and returns to the primary prompt. [#]_ + Typing an interrupt while a command is executing raises the + :exc:`KeyboardInterrupt` exception, which may be handled by a :keyword:`try` + statement. + + + .. _tut-scripts: + + Executable Python Scripts + ------------------------- + + On BSD'ish Unix systems, Python scripts can be made directly executable, like + shell scripts, by putting the line :: + - #!/usr/bin/env python3.4 ++ #!/usr/bin/env python3.5 + + (assuming that the interpreter is on the user's :envvar:`PATH`) at the beginning + of the script and giving the file an executable mode. The ``#!`` must be the + first two characters of the file. On some platforms, this first line must end + with a Unix-style line ending (``'\n'``), not a Windows (``'\r\n'``) line + ending. Note that the hash, or pound, character, ``'#'``, is used to start a + comment in Python. + + The script can be given an executable mode, or permission, using the + :program:`chmod` command. + + .. code-block:: bash + + $ chmod +x myscript.py + + On Windows systems, there is no notion of an "executable mode". The Python + installer automatically associates ``.py`` files with ``python.exe`` so that + a double-click on a Python file will run it as a script. The extension can + also be ``.pyw``, in that case, the console window that normally appears is + suppressed. + + + .. _tut-startup: + + The Interactive Startup File + ---------------------------- + + When you use Python interactively, it is frequently handy to have some standard + commands executed every time the interpreter is started. You can do this by + setting an environment variable named :envvar:`PYTHONSTARTUP` to the name of a + file containing your start-up commands. This is similar to the :file:`.profile` + feature of the Unix shells. + + This file is only read in interactive sessions, not when Python reads commands + from a script, and not when :file:`/dev/tty` is given as the explicit source of + commands (which otherwise behaves like an interactive session). It is executed + in the same namespace where interactive commands are executed, so that objects + that it defines or imports can be used without qualification in the interactive + session. You can also change the prompts ``sys.ps1`` and ``sys.ps2`` in this + file. + + If you want to read an additional start-up file from the current directory, you + can program this in the global start-up file using code like ``if + os.path.isfile('.pythonrc.py'): exec(open('.pythonrc.py').read())``. + If you want to use the startup file in a script, you must do this explicitly + in the script:: + + import os + filename = os.environ.get('PYTHONSTARTUP') + if filename and os.path.isfile(filename): + with open(filename) as fobj: + startup_file = fobj.read() + exec(startup_file) + + + .. _tut-customize: + + The Customization Modules + ------------------------- + + Python provides two hooks to let you customize it: :mod:`sitecustomize` and + :mod:`usercustomize`. To see how it works, you need first to find the location + of your user site-packages directory. Start Python and run this code:: + + >>> import site + >>> site.getusersitepackages() - '/home/user/.local/lib/python3.4/site-packages' ++ '/home/user/.local/lib/python3.5/site-packages' + + Now you can create a file named :file:`usercustomize.py` in that directory and + put anything you want in it. It will affect every invocation of Python, unless + it is started with the :option:`-s` option to disable the automatic import. + + :mod:`sitecustomize` works in the same way, but is typically created by an + administrator of the computer in the global site-packages directory, and is + imported before :mod:`usercustomize`. See the documentation of the :mod:`site` + module for more details. + + + .. rubric:: Footnotes + + .. [#] A problem with the GNU Readline package may prevent this.