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Diffstat (limited to 'Doc/tutorial/interpreter.rst')
| -rw-r--r-- | Doc/tutorial/interpreter.rst | 73 |
1 files changed, 29 insertions, 44 deletions
diff --git a/Doc/tutorial/interpreter.rst b/Doc/tutorial/interpreter.rst index b78d296..b727be0 100644 --- a/Doc/tutorial/interpreter.rst +++ b/Doc/tutorial/interpreter.rst @@ -10,38 +10,38 @@ Using the Python Interpreter Invoking the Interpreter ======================== -The Python interpreter is usually installed as :file:`/usr/local/bin/python3.9` -on those machines where it is available; putting :file:`/usr/local/bin` in your -Unix shell's search path makes it possible to start it by typing the command: +The Python interpreter is usually installed as :file:`/usr/local/bin/python` on +those machines where it is available; putting :file:`/usr/local/bin` in your +Unix shell's search path makes it possible to start it by typing the command :: -.. code-block:: text + python - python3.9 +to the shell. Since the choice of the directory where the interpreter lives is +an installation option, other places are possible; check with your local Python +guru or system administrator. (E.g., :file:`/usr/local/python` is a popular +alternative location.) -to the shell. [#]_ Since the choice of the directory where the interpreter lives -is an installation option, other places are possible; check with your local -Python guru or system administrator. (E.g., :file:`/usr/local/python` is a -popular alternative location.) +On Windows machines, the Python installation is usually placed in +:file:`C:\\Python27`, though you can change this when you're running the +installer. To add this directory to your path, you can type the following +command into the command prompt in a DOS box:: -On Windows machines where you have installed Python from the :ref:`Microsoft Store -<windows-store>`, the :file:`python3.9` command will be available. If you have -the :ref:`py.exe launcher <launcher>` installed, you can use the :file:`py` -command. See :ref:`setting-envvars` for other ways to launch Python. + set path=%path%;C:\python27 Typing an end-of-file character (:kbd:`Control-D` on Unix, :kbd:`Control-Z` on Windows) at the primary prompt causes the interpreter to exit with a zero exit status. If that doesn't work, you can exit the interpreter by typing the following command: ``quit()``. -The interpreter's line-editing features include interactive editing, history -substitution and code completion on systems that support the `GNU Readline -<https://tiswww.case.edu/php/chet/readline/rltop.html>`_ library. -Perhaps the quickest check to see whether command line editing is supported is -typing :kbd:`Control-P` to the first Python prompt you get. If it beeps, you -have command line editing; see Appendix :ref:`tut-interacting` for an -introduction to the keys. If nothing appears to happen, or if ``^P`` is -echoed, command line editing isn't available; you'll only be able to use -backspace to remove characters from the current line. +The interpreter's line-editing features usually aren't very sophisticated. On +Unix, whoever installed the interpreter may have enabled support for the GNU +readline library, which adds more elaborate interactive editing and history +features. Perhaps the quickest check to see whether command line editing is +supported is typing :kbd:`Control-P` to the first Python prompt you get. If it beeps, +you have command line editing; see Appendix :ref:`tut-interacting` for an +introduction to the keys. If nothing appears to happen, or if ``^P`` is echoed, +command line editing isn't available; you'll only be able to use backspace to +remove characters from the current line. The interpreter operates somewhat like the Unix shell: when called with standard input connected to a tty device, it reads and executes commands interactively; @@ -62,7 +62,7 @@ When a script file is used, it is sometimes useful to be able to run the script and enter interactive mode afterwards. This can be done by passing :option:`-i` before the script. -All command line options are described in :ref:`using-on-general`. +All command-line options are described in :ref:`using-on-general`. .. _tut-argpassing: @@ -97,20 +97,17 @@ before printing the first prompt: .. code-block:: shell-session - $ python3.9 - Python 3.9 (default, June 4 2019, 09:25:04) - [GCC 4.8.2] on linux + python + Python 2.7 (#1, Feb 28 2010, 00:02:06) Type "help", "copyright", "credits" or "license" for more information. >>> -.. XXX update for new releases - Continuation lines are needed when entering a multi-line construct. As an example, take a look at this :keyword:`if` statement:: - >>> the_world_is_flat = True + >>> the_world_is_flat = 1 >>> if the_world_is_flat: - ... print("Be careful not to fall off!") + ... print "Be careful not to fall off!" ... Be careful not to fall off! @@ -129,14 +126,7 @@ The Interpreter and Its Environment Source Code Encoding -------------------- -By default, Python source files are treated as encoded in UTF-8. In that -encoding, characters of most languages in the world can be used simultaneously -in string literals, identifiers and comments --- although the standard library -only uses ASCII characters for identifiers, a convention that any portable code -should follow. To display all these characters properly, your editor must -recognize that the file is UTF-8, and it must use a font that supports all the -characters in the file. - +By default, Python source files are treated as encoded in ASCII. To declare an encoding other than the default one, a special comment line should be added as the *first* line of the file. The syntax is as follows:: @@ -153,11 +143,6 @@ One exception to the *first line* rule is when the source code starts with a :ref:`UNIX "shebang" line <tut-scripts>`. In this case, the encoding declaration should be added as the second line of the file. For example:: - #!/usr/bin/env python3 + #!/usr/bin/env python # -*- coding: cp1252 -*- -.. rubric:: Footnotes - -.. [#] On Unix, the Python 3.x interpreter is by default not installed with the - executable named ``python``, so that it does not conflict with a - simultaneously installed Python 2.x executable. |