diff options
Diffstat (limited to 'Doc/tutorial')
| -rw-r--r-- | Doc/tutorial/appetite.rst | 2 | ||||
| -rw-r--r-- | Doc/tutorial/classes.rst | 14 | ||||
| -rw-r--r-- | Doc/tutorial/controlflow.rst | 11 | ||||
| -rw-r--r-- | Doc/tutorial/datastructures.rst | 64 | ||||
| -rw-r--r-- | Doc/tutorial/inputoutput.rst | 4 | ||||
| -rw-r--r-- | Doc/tutorial/interpreter.rst | 4 | ||||
| -rw-r--r-- | Doc/tutorial/introduction.rst | 6 | ||||
| -rw-r--r-- | Doc/tutorial/modules.rst | 13 | ||||
| -rw-r--r-- | Doc/tutorial/whatnow.rst | 6 |
9 files changed, 83 insertions, 41 deletions
diff --git a/Doc/tutorial/appetite.rst b/Doc/tutorial/appetite.rst index f1c80e9..120955e 100644 --- a/Doc/tutorial/appetite.rst +++ b/Doc/tutorial/appetite.rst @@ -75,8 +75,6 @@ Now that you are all excited about Python, you'll want to examine it in some more detail. Since the best way to learn a language is to use it, the tutorial invites you to play with the Python interpreter as you read. -.. % \section{Where From Here \label{where}} - In the next chapter, the mechanics of using the interpreter are explained. This is rather mundane information, but essential for trying out the examples shown later. diff --git a/Doc/tutorial/classes.rst b/Doc/tutorial/classes.rst index eb1b609..0940a75 100644 --- a/Doc/tutorial/classes.rst +++ b/Doc/tutorial/classes.rst @@ -390,7 +390,7 @@ is called with this new argument list. Random Remarks ============== -.. % [These should perhaps be placed more carefully...] +.. These should perhaps be placed more carefully... Data attributes override method attributes with the same name; to avoid accidental name conflicts, which may cause hard-to-find bugs in large programs, @@ -506,7 +506,7 @@ Derived classes may override methods of their base classes. Because methods have no special privileges when calling other methods of the same object, a method of a base class that calls another method defined in the same base class may end up calling a method of a derived class that overrides it. (For C++ -programmers: all methods in Python are effectively :keyword:`virtual`.) +programmers: all methods in Python are effectively ``virtual``.) An overriding method in a derived class may in fact want to extend rather than simply replace the base class method of the same name. There is a simple way to @@ -617,12 +617,10 @@ instance, if you have a function that formats some data from a file object, you can define a class with methods :meth:`read` and :meth:`readline` that get the data from a string buffer instead, and pass it as an argument. -.. % (Unfortunately, this -.. % technique has its limitations: a class can't define operations that -.. % are accessed by special syntax such as sequence subscripting or -.. % arithmetic operators, and assigning such a ``pseudo-file'' to -.. % \code{sys.stdin} will not cause the interpreter to read further input -.. % from it.) +.. (Unfortunately, this technique has its limitations: a class can't define + operations that are accessed by special syntax such as sequence subscripting + or arithmetic operators, and assigning such a "pseudo-file" to sys.stdin will + not cause the interpreter to read further input from it.) Instance method objects have attributes, too: ``m.__self__`` is the instance object with the method :meth:`m`, and ``m.__func__`` is the function object diff --git a/Doc/tutorial/controlflow.rst b/Doc/tutorial/controlflow.rst index 5d815d6..f51b66c 100644 --- a/Doc/tutorial/controlflow.rst +++ b/Doc/tutorial/controlflow.rst @@ -31,11 +31,8 @@ example:: There can be zero or more :keyword:`elif` parts, and the :keyword:`else` part is optional. The keyword ':keyword:`elif`' is short for 'else if', and is useful to avoid excessive indentation. An :keyword:`if` ... :keyword:`elif` ... -:keyword:`elif` ... sequence is a substitute for the :keyword:`switch` or -:keyword:`case` statements found in other languages. - -.. % Weird spacings happen here if the wrapping of the source text -.. % gets changed in the wrong way. +:keyword:`elif` ... sequence is a substitute for the ``switch`` or +``case`` statements found in other languages. .. _tut-for: @@ -53,8 +50,8 @@ iteration step and halting condition (as C), Python's :keyword:`for` statement iterates over the items of any sequence (a list or a string), in the order that they appear in the sequence. For example (no pun intended): -.. % One suggestion was to give a real C example here, but that may only -.. % serve to confuse non-C programmers. +.. One suggestion was to give a real C example here, but that may only serve to + confuse non-C programmers. :: diff --git a/Doc/tutorial/datastructures.rst b/Doc/tutorial/datastructures.rst index cf9fea3..206f056 100644 --- a/Doc/tutorial/datastructures.rst +++ b/Doc/tutorial/datastructures.rst @@ -350,6 +350,70 @@ is assigned to it). We'll find other uses for :keyword:`del` later. +Tuples and Sequences +==================== + +We saw that lists and strings have many common properties, such as indexing and +slicing operations. They are two examples of *sequence* data types (see +:ref:`typesseq`). Since Python is an evolving language, other sequence data +types may be added. There is also another standard sequence data type: the +*tuple*. + +A tuple consists of a number of values separated by commas, for instance:: + + >>> t = 12345, 54321, 'hello!' + >>> t[0] + 12345 + >>> t + (12345, 54321, 'hello!') + >>> # Tuples may be nested: + ... u = t, (1, 2, 3, 4, 5) + >>> u + ((12345, 54321, 'hello!'), (1, 2, 3, 4, 5)) + +As you see, on output tuples are always enclosed in parentheses, so that nested +tuples are interpreted correctly; they may be input with or without surrounding +parentheses, although often parentheses are necessary anyway (if the tuple is +part of a larger expression). + +Tuples have many uses. For example: (x, y) coordinate pairs, employee records +from a database, etc. Tuples, like strings, are immutable: it is not possible +to assign to the individual items of a tuple (you can simulate much of the same +effect with slicing and concatenation, though). It is also possible to create +tuples which contain mutable objects, such as lists. + +A special problem is the construction of tuples containing 0 or 1 items: the +syntax has some extra quirks to accommodate these. Empty tuples are constructed +by an empty pair of parentheses; a tuple with one item is constructed by +following a value with a comma (it is not sufficient to enclose a single value +in parentheses). Ugly, but effective. For example:: + + >>> empty = () + >>> singleton = 'hello', # <-- note trailing comma + >>> len(empty) + 0 + >>> len(singleton) + 1 + >>> singleton + ('hello',) + +The statement ``t = 12345, 54321, 'hello!'`` is an example of *tuple packing*: +the values ``12345``, ``54321`` and ``'hello!'`` are packed together in a tuple. +The reverse operation is also possible:: + + >>> x, y, z = t + +This is called, appropriately enough, *sequence unpacking*. Sequence unpacking +requires the list of variables on the left to have the same number of elements +as the length of the sequence. Note that multiple assignment is really just a +combination of tuple packing and sequence unpacking! + +There is a small bit of asymmetry here: packing multiple values always creates +a tuple, and unpacking works for any sequence. + +.. XXX Add a bit on the difference between tuples and lists. + + .. _tut-sets: Sets diff --git a/Doc/tutorial/inputoutput.rst b/Doc/tutorial/inputoutput.rst index cfea7bb..d4cad87 100644 --- a/Doc/tutorial/inputoutput.rst +++ b/Doc/tutorial/inputoutput.rst @@ -180,11 +180,9 @@ Reading and Writing Files :func:`open` returns a file object, and is most commonly used with two arguments: ``open(filename, mode)``. -.. % Opening files - :: - >>> f=open('/tmp/workfile', 'w') + >>> f = open('/tmp/workfile', 'w') >>> print(f) <open file '/tmp/workfile', mode 'w' at 80a0960> diff --git a/Doc/tutorial/interpreter.rst b/Doc/tutorial/interpreter.rst index 5c67ba9..7b1730e 100644 --- a/Doc/tutorial/interpreter.rst +++ b/Doc/tutorial/interpreter.rst @@ -212,8 +212,8 @@ 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. -.. % XXX This should probably be dumped in an appendix, since most people -.. % don't use Python interactively in non-trivial ways. +.. XXX This should probably be dumped in an appendix, since most people + don't use Python interactively in non-trivial ways. 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 diff --git a/Doc/tutorial/introduction.rst b/Doc/tutorial/introduction.rst index 4226ffd..a99e7d2 100644 --- a/Doc/tutorial/introduction.rst +++ b/Doc/tutorial/introduction.rst @@ -13,9 +13,9 @@ end a multi-line command. Many of the examples in this manual, even those entered at the interactive prompt, include comments. Comments in Python start with the hash character, -``'#'``, and extend to the end of the physical line. A comment may appear at +``#``, and extend to the end of the physical line. A comment may appear at the start of a line or following whitespace or code, but not within a string -literal. A hash character within a string literal is just a hash character. +literal. A hash character within a string literal is just a hash character. Some examples:: @@ -608,5 +608,3 @@ This example introduces several new features. Note that nothing appeared after the loop ended, until we printed a newline. - - diff --git a/Doc/tutorial/modules.rst b/Doc/tutorial/modules.rst index 2a14b35..279afc8 100644 --- a/Doc/tutorial/modules.rst +++ b/Doc/tutorial/modules.rst @@ -223,11 +223,6 @@ Some tips for experts: * The module :mod:`compileall` can create :file:`.pyc` files (or :file:`.pyo` files when :option:`-O` is used) for all modules in a directory. -* If using Python in a parallel processing system with a shared file system, - you need to patch Python to disable the creation of the compiled files - because otherwise the multiple Python interpreters will encounter race - conditions in creating them. - .. _tut-standardmodules: @@ -246,11 +241,7 @@ depends on the underlying platform For example, the :mod:`winreg` module is only provided on Windows systems. One particular module deserves some attention: :mod:`sys`, which is built into every Python interpreter. The variables ``sys.ps1`` and ``sys.ps2`` define the strings used as primary and secondary -prompts: - -.. % - -:: +prompts:: >>> import sys >>> sys.ps1 @@ -455,8 +446,6 @@ filename! On these platforms, there is no guaranteed way to know whether a file file names with a capitalized first letter.) The DOS 8+3 filename restriction adds another interesting problem for long module names. -.. % The \code{__all__} Attribute - The only solution is for the package author to provide an explicit index of the package. The import statement uses the following convention: if a package's :file:`__init__.py` code defines a list named ``__all__``, it is taken to be the diff --git a/Doc/tutorial/whatnow.rst b/Doc/tutorial/whatnow.rst index 69fa9c3..25d42a8 100644 --- a/Doc/tutorial/whatnow.rst +++ b/Doc/tutorial/whatnow.rst @@ -66,8 +66,8 @@ archives are available at http://mail.python.org/pipermail/. The FAQ answers many of the questions that come up again and again, and may already contain the solution for your problem. -.. % Postings figure based on average of last six months activity as -.. % reported by www.egroups.com; Jan. 2000 - June 2000: 21272 msgs / 182 -.. % days = 116.9 msgs / day and steadily increasing. +.. Postings figure based on average of last six months activity as + reported by www.egroups.com; Jan. 2000 - June 2000: 21272 msgs / 182 + days = 116.9 msgs / day and steadily increasing. (XXX up to date figures?) |