diff options
Diffstat (limited to 'Doc/tutorial')
| -rw-r--r-- | Doc/tutorial/classes.rst | 73 | ||||
| -rw-r--r-- | Doc/tutorial/controlflow.rst | 2 | ||||
| -rw-r--r-- | Doc/tutorial/datastructures.rst | 9 | ||||
| -rw-r--r-- | Doc/tutorial/errors.rst | 4 | ||||
| -rw-r--r-- | Doc/tutorial/interactive.rst | 153 | ||||
| -rw-r--r-- | Doc/tutorial/interpreter.rst | 35 | ||||
| -rw-r--r-- | Doc/tutorial/modules.rst | 45 | ||||
| -rw-r--r-- | Doc/tutorial/stdlib.rst | 4 | ||||
| -rw-r--r-- | Doc/tutorial/stdlib2.rst | 2 | ||||
| -rw-r--r-- | Doc/tutorial/whatnow.rst | 4 |
10 files changed, 146 insertions, 185 deletions
diff --git a/Doc/tutorial/classes.rst b/Doc/tutorial/classes.rst index 08072a3..11e07e3 100644 --- a/Doc/tutorial/classes.rst +++ b/Doc/tutorial/classes.rst @@ -387,6 +387,77 @@ object and the argument list, and the function object is called with this new argument list. +.. _tut-class-and-instance-variables: + +Class and Instance Variables +---------------------------- + +Generally speaking, instance variables are for data unique to each instance +and class variables are for attributes and methods shared by all instances +of the class:: + + class Dog: + + kind = 'canine' # class variable shared by all instances + + def __init__(self, name): + self.name = name # instance variable unique to each instance + + >>> d = Dog('Fido') + >>> e = Dog('Buddy') + >>> d.kind # shared by all dogs + 'canine' + >>> e.kind # shared by all dogs + 'canine' + >>> d.name # unique to d + 'Fido' + >>> e.name # unique to e + 'Buddy' + +As discussed in :ref:`tut-object`, shared data can have possibly surprising +effects with involving :term:`mutable` objects such as lists and dictionaries. +For example, the *tricks* list in the following code should not be used as a +class variable because just a single list would be shared by all *Dog* +instances:: + + class Dog: + + tricks = [] # mistaken use of a class variable + + def __init__(self, name): + self.name = name + + def add_trick(self, trick): + self.tricks.append(trick) + + >>> d = Dog('Fido') + >>> e = Dog('Buddy') + >>> d.add_trick('roll over') + >>> e.add_trick('play dead') + >>> d.tricks # unexpectedly shared by all dogs + ['roll over', 'play dead'] + +Correct design of the class should use an instance variable instead:: + + class Dog: + + def __init__(self, name): + self.name = name + self.tricks = [] # creates a new empty list for each dog + + def add_trick(self, trick): + self.tricks.append(trick) + + >>> d = Dog('Fido') + >>> e = Dog('Buddy') + >>> d.add_trick('roll over') + >>> e.add_trick('play dead') + >>> d.tricks + ['roll over'] + >>> e.tricks + ['play dead'] + + .. _tut-remarks: Random Remarks @@ -731,7 +802,7 @@ using a :keyword:`for` statement:: for char in "123": print(char) for line in open("myfile.txt"): - print(line) + print(line, end='') This style of access is clear, concise, and convenient. The use of iterators pervades and unifies Python. Behind the scenes, the :keyword:`for` statement diff --git a/Doc/tutorial/controlflow.rst b/Doc/tutorial/controlflow.rst index 97aea4f..ef50731 100644 --- a/Doc/tutorial/controlflow.rst +++ b/Doc/tutorial/controlflow.rst @@ -370,7 +370,7 @@ defined to allow. For example:: return False retries = retries - 1 if retries < 0: - raise IOError('uncooperative user') + raise OSError('uncooperative user') print(complaint) This function can be called in several ways: diff --git a/Doc/tutorial/datastructures.rst b/Doc/tutorial/datastructures.rst index 24d2d2e..f2b66f7 100644 --- a/Doc/tutorial/datastructures.rst +++ b/Doc/tutorial/datastructures.rst @@ -111,10 +111,15 @@ An example that uses most of the list methods:: >>> a.sort() >>> a [-1, 1, 66.25, 333, 333, 1234.5] + >>> a.pop() + 1234.5 + >>> a + [-1, 1, 66.25, 333, 333] You might have noticed that methods like ``insert``, ``remove`` or ``sort`` that -modify the list have no return value printed -- they return ``None``. [1]_ This -is a design principle for all mutable data structures in Python. +only modify the list have no return value printed -- they return the default +``None``. [1]_ This is a design principle for all mutable data structures in +Python. .. _tut-lists-as-stacks: diff --git a/Doc/tutorial/errors.rst b/Doc/tutorial/errors.rst index 4282151..d048ae9 100644 --- a/Doc/tutorial/errors.rst +++ b/Doc/tutorial/errors.rst @@ -131,8 +131,8 @@ the exception (allowing a caller to handle the exception as well):: f = open('myfile.txt') s = f.readline() i = int(s.strip()) - except IOError as err: - print("I/O error: {0}".format(err)) + except OSError as err: + print("OS error: {0}".format(err)) except ValueError: print("Could not convert data to an integer.") except: diff --git a/Doc/tutorial/interactive.rst b/Doc/tutorial/interactive.rst index 36acb06..abf30f0 100644 --- a/Doc/tutorial/interactive.rst +++ b/Doc/tutorial/interactive.rst @@ -7,140 +7,27 @@ Interactive Input Editing and History Substitution Some versions of the Python interpreter support editing of the current input line and history substitution, similar to facilities found in the Korn shell and the GNU Bash shell. This is implemented using the `GNU Readline`_ library, -which supports Emacs-style and vi-style editing. This library has its own -documentation which I won't duplicate here; however, the basics are easily -explained. The interactive editing and history described here are optionally -available in the Unix and Cygwin versions of the interpreter. - -This chapter does *not* document the editing facilities of Mark Hammond's -PythonWin package or the Tk-based environment, IDLE, distributed with Python. -The command line history recall which operates within DOS boxes on NT and some -other DOS and Windows flavors is yet another beast. - - -.. _tut-lineediting: - -Line Editing -============ - -If supported, input line editing is active whenever the interpreter prints a -primary or secondary prompt. The current line can be edited using the -conventional Emacs control characters. The most important of these are: -:kbd:`C-A` (Control-A) moves the cursor to the beginning of the line, :kbd:`C-E` -to the end, :kbd:`C-B` moves it one position to the left, :kbd:`C-F` to the -right. Backspace erases the character to the left of the cursor, :kbd:`C-D` the -character to its right. :kbd:`C-K` kills (erases) the rest of the line to the -right of the cursor, :kbd:`C-Y` yanks back the last killed string. -:kbd:`C-underscore` undoes the last change you made; it can be repeated for -cumulative effect. - - -.. _tut-history: - -History Substitution -==================== - -History substitution works as follows. All non-empty input lines issued are -saved in a history buffer, and when a new prompt is given you are positioned on -a new line at the bottom of this buffer. :kbd:`C-P` moves one line up (back) in -the history buffer, :kbd:`C-N` moves one down. Any line in the history buffer -can be edited; an asterisk appears in front of the prompt to mark a line as -modified. Pressing the :kbd:`Return` key passes the current line to the -interpreter. :kbd:`C-R` starts an incremental reverse search; :kbd:`C-S` starts -a forward search. +which supports various styles of editing. This library has its own +documentation which we won't duplicate here. .. _tut-keybindings: -Key Bindings -============ - -The key bindings and some other parameters of the Readline library can be -customized by placing commands in an initialization file called -:file:`~/.inputrc`. Key bindings have the form :: - - key-name: function-name - -or :: - - "string": function-name - -and options can be set with :: - - set option-name value - -For example:: - - # I prefer vi-style editing: - set editing-mode vi - - # Edit using a single line: - set horizontal-scroll-mode On +Tab Completion and History Editing +================================== - # Rebind some keys: - Meta-h: backward-kill-word - "\C-u": universal-argument - "\C-x\C-r": re-read-init-file - -Note that the default binding for :kbd:`Tab` in Python is to insert a :kbd:`Tab` -character instead of Readline's default filename completion function. If you -insist, you can override this by putting :: - - Tab: complete - -in your :file:`~/.inputrc`. (Of course, this makes it harder to type indented -continuation lines if you're accustomed to using :kbd:`Tab` for that purpose.) - -.. index:: - module: rlcompleter - module: readline - -Automatic completion of variable and module names is optionally available. To -enable it in the interpreter's interactive mode, add the following to your -startup file: [#]_ :: - - import rlcompleter, readline - readline.parse_and_bind('tab: complete') - -This binds the :kbd:`Tab` key to the completion function, so hitting the -:kbd:`Tab` key twice suggests completions; it looks at Python statement names, -the current local variables, and the available module names. For dotted -expressions such as ``string.a``, it will evaluate the expression up to the -final ``'.'`` and then suggest completions from the attributes of the resulting -object. Note that this may execute application-defined code if an object with a -:meth:`__getattr__` method is part of the expression. - -A more capable startup file might look like this example. Note that this -deletes the names it creates once they are no longer needed; this is done since -the startup file is executed in the same namespace as the interactive commands, -and removing the names avoids creating side effects in the interactive -environment. You may find it convenient to keep some of the imported modules, -such as :mod:`os`, which turn out to be needed in most sessions with the -interpreter. :: - - # Add auto-completion and a stored history file of commands to your Python - # interactive interpreter. Requires Python 2.0+, readline. Autocomplete is - # bound to the Esc key by default (you can change it - see readline docs). - # - # Store the file in ~/.pystartup, and set an environment variable to point - # to it: "export PYTHONSTARTUP=~/.pystartup" in bash. - - import atexit - import os - import readline - import rlcompleter - - historyPath = os.path.expanduser("~/.pyhistory") - - def save_history(historyPath=historyPath): - import readline - readline.write_history_file(historyPath) - - if os.path.exists(historyPath): - readline.read_history_file(historyPath) - - atexit.register(save_history) - del os, atexit, readline, rlcompleter, save_history, historyPath +Completion of variable and module names is +:ref:`automatically enabled <rlcompleter-config>` at interpreter startup so +that the :kbd:`Tab` key invokes the completion function; it looks at +Python statement names, the current local variables, and the available +module names. For dotted expressions such as ``string.a``, it will evaluate +the expression up to the final ``'.'`` and then suggest completions from +the attributes of the resulting object. Note that this may execute +application-defined code if an object with a :meth:`__getattr__` method +is part of the expression. The default configuration also saves your +history into a file named :file:`.python_history` in your user directory. +The history will be available again during the next interactive interpreter +session. .. _tut-commentary: @@ -162,14 +49,6 @@ into other applications. Another similar enhanced interactive environment is bpython_. -.. rubric:: Footnotes - -.. [#] Python will execute the contents of a file identified by the - :envvar:`PYTHONSTARTUP` environment variable when you start an interactive - interpreter. To customize Python even for non-interactive mode, see - :ref:`tut-customize`. - - .. _GNU Readline: http://tiswww.case.edu/php/chet/readline/rltop.html .. _IPython: http://ipython.scipy.org/ .. _bpython: http://www.bpython-interpreter.org/ diff --git a/Doc/tutorial/interpreter.rst b/Doc/tutorial/interpreter.rst index cdc2bf2..44dc6d1 100644 --- a/Doc/tutorial/interpreter.rst +++ b/Doc/tutorial/interpreter.rst @@ -10,13 +10,13 @@ Using the Python Interpreter Invoking the Interpreter ======================== -The Python interpreter is usually installed as :file:`/usr/local/bin/python3.3` +The Python interpreter is usually installed as :file:`/usr/local/bin/python3.4` 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 - python3.3 + python3.4 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 @@ -24,26 +24,25 @@ 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:\\Python33`, though you can change this when you're running the +:file:`C:\\Python34`, 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:: - set path=%path%;C:\python33 + set path=%path%;C:\python34 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 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 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 include interactive editing, history +substitution and code completion on systems that support readline. Perhaps the +quickest check to see whether command line editing is supported is typing +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; @@ -95,9 +94,9 @@ with the *secondary prompt*, by default three dots (``...``). The interpreter prints a welcome message stating its version number and a copyright notice before printing the first prompt:: - $ python3.3 - Python 3.3 (default, Sep 24 2012, 09:25:04) - [GCC 4.6.3] on linux2 + $ python3.4 + Python 3.4 (default, Mar 16 2014, 09:25:04) + [GCC 4.8.2] on linux Type "help", "copyright", "credits" or "license" for more information. >>> @@ -106,7 +105,7 @@ before printing the first prompt:: 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 = 1 + >>> the_world_is_flat = True >>> if the_world_is_flat: ... print("Be careful not to fall off!") ... @@ -149,7 +148,7 @@ 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 python3.3 + #! /usr/bin/env python3.4 (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 diff --git a/Doc/tutorial/modules.rst b/Doc/tutorial/modules.rst index 1902964..fd361ae 100644 --- a/Doc/tutorial/modules.rst +++ b/Doc/tutorial/modules.rst @@ -165,10 +165,16 @@ a built-in module with that name. If not found, it then searches for a file named :file:`spam.py` in a list of directories given by the variable :data:`sys.path`. :data:`sys.path` is initialized from these locations: -* the directory containing the input script (or the current directory). +* The directory containing the input script (or the current directory when no + file is specified). * :envvar:`PYTHONPATH` (a list of directory names, with the same syntax as the shell variable :envvar:`PATH`). -* the installation-dependent default. +* The installation-dependent default. + +.. note:: + On file systems which support symlinks, the directory containing the input + script is calculated after the symlink is followed. In other words the + directory containing the symlink is **not** added to the module search path. After initialization, Python programs can modify :data:`sys.path`. The directory containing the script being run is placed at the beginning of the @@ -278,24 +284,23 @@ defines. It returns a sorted list of strings:: >>> dir(fibo) ['__name__', 'fib', 'fib2'] >>> dir(sys) # doctest: +NORMALIZE_WHITESPACE - ['__displayhook__', '__doc__', '__egginsert', '__excepthook__', - '__loader__', '__name__', '__package__', '__plen', '__stderr__', - '__stdin__', '__stdout__', '_clear_type_cache', '_current_frames', - '_debugmallocstats', '_getframe', '_home', '_mercurial', '_xoptions', - 'abiflags', 'api_version', 'argv', 'base_exec_prefix', 'base_prefix', - 'builtin_module_names', 'byteorder', 'call_tracing', 'callstats', - 'copyright', 'displayhook', 'dont_write_bytecode', 'exc_info', - 'excepthook', 'exec_prefix', 'executable', 'exit', 'flags', 'float_info', - 'float_repr_style', 'getcheckinterval', 'getdefaultencoding', - 'getdlopenflags', 'getfilesystemencoding', 'getobjects', 'getprofile', - 'getrecursionlimit', 'getrefcount', 'getsizeof', 'getswitchinterval', - 'gettotalrefcount', 'gettrace', 'hash_info', 'hexversion', - 'implementation', 'int_info', 'intern', 'maxsize', 'maxunicode', - 'meta_path', 'modules', 'path', 'path_hooks', 'path_importer_cache', - 'platform', 'prefix', 'ps1', 'setcheckinterval', 'setdlopenflags', - 'setprofile', 'setrecursionlimit', 'setswitchinterval', 'settrace', - 'stderr', 'stdin', 'stdout', 'thread_info', 'version', 'version_info', - 'warnoptions'] + ['__displayhook__', '__doc__', '__excepthook__', '__loader__', '__name__', + '__package__', '__stderr__', '__stdin__', '__stdout__', + '_clear_type_cache', '_current_frames', '_debugmallocstats', '_getframe', + '_home', '_mercurial', '_xoptions', 'abiflags', 'api_version', 'argv', + 'base_exec_prefix', 'base_prefix', 'builtin_module_names', 'byteorder', + 'call_tracing', 'callstats', 'copyright', 'displayhook', + 'dont_write_bytecode', 'exc_info', 'excepthook', 'exec_prefix', + 'executable', 'exit', 'flags', 'float_info', 'float_repr_style', + 'getcheckinterval', 'getdefaultencoding', 'getdlopenflags', + 'getfilesystemencoding', 'getobjects', 'getprofile', 'getrecursionlimit', + 'getrefcount', 'getsizeof', 'getswitchinterval', 'gettotalrefcount', + 'gettrace', 'hash_info', 'hexversion', 'implementation', 'int_info', + 'intern', 'maxsize', 'maxunicode', 'meta_path', 'modules', 'path', + 'path_hooks', 'path_importer_cache', 'platform', 'prefix', 'ps1', + 'setcheckinterval', 'setdlopenflags', 'setprofile', 'setrecursionlimit', + 'setswitchinterval', 'settrace', 'stderr', 'stdin', 'stdout', + 'thread_info', 'version', 'version_info', 'warnoptions'] Without arguments, :func:`dir` lists the names you have defined currently:: diff --git a/Doc/tutorial/stdlib.rst b/Doc/tutorial/stdlib.rst index 7e7a154..cd73bc2 100644 --- a/Doc/tutorial/stdlib.rst +++ b/Doc/tutorial/stdlib.rst @@ -15,7 +15,7 @@ operating system:: >>> import os >>> os.getcwd() # Return the current working directory - 'C:\\Python33' + 'C:\\Python34' >>> os.chdir('/server/accesslogs') # Change current working directory >>> os.system('mkdir today') # Run the command mkdir in the system shell 0 @@ -40,7 +40,9 @@ a higher level interface that is easier to use:: >>> import shutil >>> shutil.copyfile('data.db', 'archive.db') + 'archive.db' >>> shutil.move('/build/executables', 'installdir') + 'installdir' .. _tut-file-wildcards: diff --git a/Doc/tutorial/stdlib2.rst b/Doc/tutorial/stdlib2.rst index c1dd69a..c0197ea 100644 --- a/Doc/tutorial/stdlib2.rst +++ b/Doc/tutorial/stdlib2.rst @@ -277,7 +277,7 @@ applications include caching objects that are expensive to create:: Traceback (most recent call last): File "<stdin>", line 1, in <module> d['primary'] # entry was automatically removed - File "C:/python33/lib/weakref.py", line 46, in __getitem__ + File "C:/python34/lib/weakref.py", line 46, in __getitem__ o = self.data[key]() KeyError: 'primary' diff --git a/Doc/tutorial/whatnow.rst b/Doc/tutorial/whatnow.rst index 7fcbdc3f..979f587 100644 --- a/Doc/tutorial/whatnow.rst +++ b/Doc/tutorial/whatnow.rst @@ -21,8 +21,8 @@ the set are: and many other tasks. Skimming through the Library Reference will give you an idea of what's available. -* :ref:`install-index` explains how to install external modules written by other - Python users. +* :ref:`installing-index` explains how to install additional modules written + by other Python users. * :ref:`reference-index`: A detailed explanation of Python's syntax and semantics. It's heavy reading, but is useful as a complete guide to the |