558 lines
27 KiB
ReStructuredText
558 lines
27 KiB
ReStructuredText
.. _glossary:
|
|
|
|
********
|
|
Glossary
|
|
********
|
|
|
|
.. if you add new entries, keep the alphabetical sorting!
|
|
|
|
.. glossary::
|
|
|
|
``>>>``
|
|
The default Python prompt of the interactive shell. Often seen for code
|
|
examples which can be executed interactively in the interpreter.
|
|
|
|
``...``
|
|
The default Python prompt of the interactive shell when entering code for
|
|
an indented code block or within a pair of matching left and right
|
|
delimiters (parentheses, square brackets or curly braces).
|
|
|
|
2to3
|
|
A tool that tries to convert Python 2.x code to Python 3.x code by
|
|
handling most of the incompatibilites which can be detected by parsing the
|
|
source and traversing the parse tree.
|
|
|
|
2to3 is available in the standard library as :mod:`lib2to3`; a standalone
|
|
entry point is provided as :file:`Tools/scripts/2to3`. See
|
|
:ref:`2to3-reference`.
|
|
|
|
abstract base class
|
|
Abstract Base Classes (abbreviated ABCs) complement :term:`duck-typing` by
|
|
providing a way to define interfaces when other techniques like
|
|
:func:`hasattr` would be clumsy. Python comes with many built-in ABCs for
|
|
data structures (in the :mod:`collections` module), numbers (in the
|
|
:mod:`numbers` module), and streams (in the :mod:`io` module). You can
|
|
create your own ABC with the :mod:`abc` module.
|
|
|
|
argument
|
|
A value passed to a function or method, assigned to a named local
|
|
variable in the function body. A function or method may have both
|
|
positional arguments and keyword arguments in its definition.
|
|
Positional and keyword arguments may be variable-length: ``*`` accepts
|
|
or passes (if in the function definition or call) several positional
|
|
arguments in a list, while ``**`` does the same for keyword arguments
|
|
in a dictionary.
|
|
|
|
Any expression may be used within the argument list, and the evaluated
|
|
value is passed to the local variable.
|
|
|
|
attribute
|
|
A value associated with an object which is referenced by name using
|
|
dotted expressions. For example, if an object *o* has an attribute
|
|
*a* it would be referenced as *o.a*.
|
|
|
|
BDFL
|
|
Benevolent Dictator For Life, a.k.a. `Guido van Rossum
|
|
<http://www.python.org/~guido/>`_, Python's creator.
|
|
|
|
bytecode
|
|
Python source code is compiled into bytecode, the internal representation
|
|
of a Python program in the interpreter. The bytecode is also cached in
|
|
``.pyc`` and ``.pyo`` files so that executing the same file is faster the
|
|
second time (recompilation from source to bytecode can be avoided). This
|
|
"intermediate language" is said to run on a :term:`virtual machine`
|
|
that executes the machine code corresponding to each bytecode.
|
|
|
|
class
|
|
A template for creating user-defined objects. Class definitions
|
|
normally contain method definitions which operate on instances of the
|
|
class.
|
|
|
|
classic class
|
|
Any class which does not inherit from :class:`object`. See
|
|
:term:`new-style class`. Classic classes will be removed in Python 3.0.
|
|
|
|
coercion
|
|
The implicit conversion of an instance of one type to another during an
|
|
operation which involves two arguments of the same type. For example,
|
|
``int(3.15)`` converts the floating point number to the integer ``3``, but
|
|
in ``3+4.5``, each argument is of a different type (one int, one float),
|
|
and both must be converted to the same type before they can be added or it
|
|
will raise a ``TypeError``. Coercion between two operands can be
|
|
performed with the ``coerce`` built-in function; thus, ``3+4.5`` is
|
|
equivalent to calling ``operator.add(*coerce(3, 4.5))`` and results in
|
|
``operator.add(3.0, 4.5)``. Without coercion, all arguments of even
|
|
compatible types would have to be normalized to the same value by the
|
|
programmer, e.g., ``float(3)+4.5`` rather than just ``3+4.5``.
|
|
|
|
complex number
|
|
An extension of the familiar real number system in which all numbers are
|
|
expressed as a sum of a real part and an imaginary part. Imaginary
|
|
numbers are real multiples of the imaginary unit (the square root of
|
|
``-1``), often written ``i`` in mathematics or ``j`` in
|
|
engineering. Python has built-in support for complex numbers, which are
|
|
written with this latter notation; the imaginary part is written with a
|
|
``j`` suffix, e.g., ``3+1j``. To get access to complex equivalents of the
|
|
:mod:`math` module, use :mod:`cmath`. Use of complex numbers is a fairly
|
|
advanced mathematical feature. If you're not aware of a need for them,
|
|
it's almost certain you can safely ignore them.
|
|
|
|
context manager
|
|
An object which controls the environment seen in a :keyword:`with`
|
|
statement by defining :meth:`__enter__` and :meth:`__exit__` methods.
|
|
See :pep:`343`.
|
|
|
|
CPython
|
|
The canonical implementation of the Python programming language. The
|
|
term "CPython" is used in contexts when necessary to distinguish this
|
|
implementation from others such as Jython or IronPython.
|
|
|
|
decorator
|
|
A function returning another function, usually applied as a function
|
|
transformation using the ``@wrapper`` syntax. Common examples for
|
|
decorators are :func:`classmethod` and :func:`staticmethod`.
|
|
|
|
The decorator syntax is merely syntactic sugar, the following two
|
|
function definitions are semantically equivalent::
|
|
|
|
def f(...):
|
|
...
|
|
f = staticmethod(f)
|
|
|
|
@staticmethod
|
|
def f(...):
|
|
...
|
|
|
|
See :ref:`the documentation for function definition <function>` for more
|
|
about decorators.
|
|
|
|
descriptor
|
|
Any *new-style* object which defines the methods :meth:`__get__`,
|
|
:meth:`__set__`, or :meth:`__delete__`. When a class attribute is a
|
|
descriptor, its special binding behavior is triggered upon attribute
|
|
lookup. Normally, using *a.b* to get, set or delete an attribute looks up
|
|
the object named *b* in the class dictionary for *a*, but if *b* is a
|
|
descriptor, the respective descriptor method gets called. Understanding
|
|
descriptors is a key to a deep understanding of Python because they are
|
|
the basis for many features including functions, methods, properties,
|
|
class methods, static methods, and reference to super classes.
|
|
|
|
For more information about descriptors' methods, see :ref:`descriptors`.
|
|
|
|
dictionary
|
|
An associative array, where arbitrary keys are mapped to values. The use
|
|
of :class:`dict` closely resembles that for :class:`list`, but the keys can
|
|
be any object with a :meth:`__hash__` function, not just integers.
|
|
Called a hash in Perl.
|
|
|
|
docstring
|
|
A string literal which appears as the first expression in a class,
|
|
function or module. While ignored when the suite is executed, it is
|
|
recognized by the compiler and put into the :attr:`__doc__` attribute
|
|
of the enclosing class, function or module. Since it is available via
|
|
introspection, it is the canonical place for documentation of the
|
|
object.
|
|
|
|
duck-typing
|
|
A pythonic programming style which determines an object's type by inspection
|
|
of its method or attribute signature rather than by explicit relationship
|
|
to some type object ("If it looks like a duck and quacks like a duck, it
|
|
must be a duck.") By emphasizing interfaces rather than specific types,
|
|
well-designed code improves its flexibility by allowing polymorphic
|
|
substitution. Duck-typing avoids tests using :func:`type` or
|
|
:func:`isinstance`. (Note, however, that duck-typing can be complemented
|
|
with abstract base classes.) Instead, it typically employs :func:`hasattr`
|
|
tests or :term:`EAFP` programming.
|
|
|
|
EAFP
|
|
Easier to ask for forgiveness than permission. This common Python coding
|
|
style assumes the existence of valid keys or attributes and catches
|
|
exceptions if the assumption proves false. This clean and fast style is
|
|
characterized by the presence of many :keyword:`try` and :keyword:`except`
|
|
statements. The technique contrasts with the :term:`LBYL` style
|
|
common to many other languages such as C.
|
|
|
|
expression
|
|
A piece of syntax which can be evaluated to some value. In other words,
|
|
an expression is an accumulation of expression elements like literals, names,
|
|
attribute access, operators or function calls which all return a value.
|
|
In contrast to many other languages, not all language constructs are expressions.
|
|
There are also :term:`statement`\s which cannot be used as expressions,
|
|
such as :keyword:`print` or :keyword:`if`. Assignments are also statements,
|
|
not expressions.
|
|
|
|
extension module
|
|
A module written in C or C++, using Python's C API to interact with the core and
|
|
with user code.
|
|
|
|
finder
|
|
An object that tries to find the :term:`loader` for a module. It must
|
|
implement a method named :meth:`find_module`. See :pep:`302` for
|
|
details.
|
|
|
|
function
|
|
A series of statements which returns some value to a caller. It can also
|
|
be passed zero or more arguments which may be used in the execution of
|
|
the body. See also :term:`argument` and :term:`method`.
|
|
|
|
__future__
|
|
A pseudo module which programmers can use to enable new language features
|
|
which are not compatible with the current interpreter. For example, the
|
|
expression ``11/4`` currently evaluates to ``2``. If the module in which
|
|
it is executed had enabled *true division* by executing::
|
|
|
|
from __future__ import division
|
|
|
|
the expression ``11/4`` would evaluate to ``2.75``. By importing the
|
|
:mod:`__future__` module and evaluating its variables, you can see when a
|
|
new feature was first added to the language and when it will become the
|
|
default::
|
|
|
|
>>> import __future__
|
|
>>> __future__.division
|
|
_Feature((2, 2, 0, 'alpha', 2), (3, 0, 0, 'alpha', 0), 8192)
|
|
|
|
garbage collection
|
|
The process of freeing memory when it is not used anymore. Python
|
|
performs garbage collection via reference counting and a cyclic garbage
|
|
collector that is able to detect and break reference cycles.
|
|
|
|
generator
|
|
A function which returns an iterator. It looks like a normal function
|
|
except that values are returned to the caller using a :keyword:`yield`
|
|
statement instead of a :keyword:`return` statement. Generator functions
|
|
often contain one or more :keyword:`for` or :keyword:`while` loops which
|
|
:keyword:`yield` elements back to the caller. The function execution is
|
|
stopped at the :keyword:`yield` keyword (returning the result) and is
|
|
resumed there when the next element is requested by calling the
|
|
:meth:`next` method of the returned iterator.
|
|
|
|
.. index:: single: generator expression
|
|
|
|
generator expression
|
|
An expression that returns a generator. It looks like a normal expression
|
|
followed by a :keyword:`for` expression defining a loop variable, range,
|
|
and an optional :keyword:`if` expression. The combined expression
|
|
generates values for an enclosing function::
|
|
|
|
>>> sum(i*i for i in range(10)) # sum of squares 0, 1, 4, ... 81
|
|
285
|
|
|
|
GIL
|
|
See :term:`global interpreter lock`.
|
|
|
|
global interpreter lock
|
|
The lock used by Python threads to assure that only one thread
|
|
executes in the :term:`CPython` :term:`virtual machine` at a time.
|
|
This simplifies the CPython implementation by assuring that no two
|
|
processes can access the same memory at the same time. Locking the
|
|
entire interpreter makes it easier for the interpreter to be
|
|
multi-threaded, at the expense of much of the parallelism afforded by
|
|
multi-processor machines. Efforts have been made in the past to
|
|
create a "free-threaded" interpreter (one which locks shared data at a
|
|
much finer granularity), but so far none have been successful because
|
|
performance suffered in the common single-processor case.
|
|
|
|
hashable
|
|
An object is *hashable* if it has a hash value which never changes during
|
|
its lifetime (it needs a :meth:`__hash__` method), and can be compared to
|
|
other objects (it needs an :meth:`__eq__` or :meth:`__cmp__` method).
|
|
Hashable objects which compare equal must have the same hash value.
|
|
|
|
Hashability makes an object usable as a dictionary key and a set member,
|
|
because these data structures use the hash value internally.
|
|
|
|
All of Python's immutable built-in objects are hashable, while no mutable
|
|
containers (such as lists or dictionaries) are. Objects which are
|
|
instances of user-defined classes are hashable by default; they all
|
|
compare unequal, and their hash value is their :func:`id`.
|
|
|
|
IDLE
|
|
An Integrated Development Environment for Python. IDLE is a basic editor
|
|
and interpreter environment which ships with the standard distribution of
|
|
Python. Good for beginners, it also serves as clear example code for
|
|
those wanting to implement a moderately sophisticated, multi-platform GUI
|
|
application.
|
|
|
|
immutable
|
|
An object with a fixed value. Immutable objects include numbers, strings and
|
|
tuples. Such an object cannot be altered. A new object has to
|
|
be created if a different value has to be stored. They play an important
|
|
role in places where a constant hash value is needed, for example as a key
|
|
in a dictionary.
|
|
|
|
integer division
|
|
Mathematical division discarding any remainder. For example, the
|
|
expression ``11/4`` currently evaluates to ``2`` in contrast to the
|
|
``2.75`` returned by float division. Also called *floor division*.
|
|
When dividing two integers the outcome will always be another integer
|
|
(having the floor function applied to it). However, if one of the operands
|
|
is another numeric type (such as a :class:`float`), the result will be
|
|
coerced (see :term:`coercion`) to a common type. For example, an integer
|
|
divided by a float will result in a float value, possibly with a decimal
|
|
fraction. Integer division can be forced by using the ``//`` operator
|
|
instead of the ``/`` operator. See also :term:`__future__`.
|
|
|
|
importer
|
|
An object that both finds and loads a module; both a
|
|
:term:`finder` and :term:`loader` object.
|
|
|
|
interactive
|
|
Python has an interactive interpreter which means you can enter
|
|
statements and expressions at the interpreter prompt, immediately
|
|
execute them and see their results. Just launch ``python`` with no
|
|
arguments (possibly by selecting it from your computer's main
|
|
menu). It is a very powerful way to test out new ideas or inspect
|
|
modules and packages (remember ``help(x)``).
|
|
|
|
interpreted
|
|
Python is an interpreted language, as opposed to a compiled one,
|
|
though the distinction can be blurry because of the presence of the
|
|
bytecode compiler. This means that source files can be run directly
|
|
without explicitly creating an executable which is then run.
|
|
Interpreted languages typically have a shorter development/debug cycle
|
|
than compiled ones, though their programs generally also run more
|
|
slowly. See also :term:`interactive`.
|
|
|
|
iterable
|
|
A container object capable of returning its members one at a
|
|
time. Examples of iterables include all sequence types (such as
|
|
:class:`list`, :class:`str`, and :class:`tuple`) and some non-sequence
|
|
types like :class:`dict` and :class:`file` and objects of any classes you
|
|
define with an :meth:`__iter__` or :meth:`__getitem__` method. Iterables
|
|
can be used in a :keyword:`for` loop and in many other places where a
|
|
sequence is needed (:func:`zip`, :func:`map`, ...). When an iterable
|
|
object is passed as an argument to the built-in function :func:`iter`, it
|
|
returns an iterator for the object. This iterator is good for one pass
|
|
over the set of values. When using iterables, it is usually not necessary
|
|
to call :func:`iter` or deal with iterator objects yourself. The ``for``
|
|
statement does that automatically for you, creating a temporary unnamed
|
|
variable to hold the iterator for the duration of the loop. See also
|
|
:term:`iterator`, :term:`sequence`, and :term:`generator`.
|
|
|
|
iterator
|
|
An object representing a stream of data. Repeated calls to the iterator's
|
|
:meth:`next` method return successive items in the stream. When no more
|
|
data are available a :exc:`StopIteration` exception is raised instead. At
|
|
this point, the iterator object is exhausted and any further calls to its
|
|
:meth:`next` method just raise :exc:`StopIteration` again. Iterators are
|
|
required to have an :meth:`__iter__` method that returns the iterator
|
|
object itself so every iterator is also iterable and may be used in most
|
|
places where other iterables are accepted. One notable exception is code
|
|
which attempts multiple iteration passes. A container object (such as a
|
|
:class:`list`) produces a fresh new iterator each time you pass it to the
|
|
:func:`iter` function or use it in a :keyword:`for` loop. Attempting this
|
|
with an iterator will just return the same exhausted iterator object used
|
|
in the previous iteration pass, making it appear like an empty container.
|
|
|
|
More information can be found in :ref:`typeiter`.
|
|
|
|
keyword argument
|
|
Arguments which are preceded with a ``variable_name=`` in the call.
|
|
The variable name designates the local name in the function to which the
|
|
value is assigned. ``**`` is used to accept or pass a dictionary of
|
|
keyword arguments. See :term:`argument`.
|
|
|
|
lambda
|
|
An anonymous inline function consisting of a single :term:`expression`
|
|
which is evaluated when the function is called. The syntax to create
|
|
a lambda function is ``lambda [arguments]: expression``
|
|
|
|
LBYL
|
|
Look before you leap. This coding style explicitly tests for
|
|
pre-conditions before making calls or lookups. This style contrasts with
|
|
the :term:`EAFP` approach and is characterized by the presence of many
|
|
:keyword:`if` statements.
|
|
|
|
list
|
|
A built-in Python :term:`sequence`. Despite its name it is more akin
|
|
to an array in other languages than to a linked list since access to
|
|
elements are O(1).
|
|
|
|
list comprehension
|
|
A compact way to process all or part of the elements in a sequence and
|
|
return a list with the results. ``result = ["0x%02x" % x for x in
|
|
range(256) if x % 2 == 0]`` generates a list of strings containing
|
|
even hex numbers (0x..) in the range from 0 to 255. The :keyword:`if`
|
|
clause is optional. If omitted, all elements in ``range(256)`` are
|
|
processed.
|
|
|
|
loader
|
|
An object that loads a module. It must define a method named
|
|
:meth:`load_module`. A loader is typically returned by a
|
|
:term:`finder`. See :pep:`302` for details.
|
|
|
|
mapping
|
|
A container object (such as :class:`dict`) which supports arbitrary key
|
|
lookups using the special method :meth:`__getitem__`.
|
|
|
|
metaclass
|
|
The class of a class. Class definitions create a class name, a class
|
|
dictionary, and a list of base classes. The metaclass is responsible for
|
|
taking those three arguments and creating the class. Most object oriented
|
|
programming languages provide a default implementation. What makes Python
|
|
special is that it is possible to create custom metaclasses. Most users
|
|
never need this tool, but when the need arises, metaclasses can provide
|
|
powerful, elegant solutions. They have been used for logging attribute
|
|
access, adding thread-safety, tracking object creation, implementing
|
|
singletons, and many other tasks.
|
|
|
|
More information can be found in :ref:`metaclasses`.
|
|
|
|
method
|
|
A function which is defined inside a class body. If called as an attribute
|
|
of an instance of that class, the method will get the instance object as
|
|
its first :term:`argument` (which is usually called ``self``).
|
|
See :term:`function` and :term:`nested scope`.
|
|
|
|
mutable
|
|
Mutable objects can change their value but keep their :func:`id`. See
|
|
also :term:`immutable`.
|
|
|
|
named tuple
|
|
Any tuple-like class whose indexable elements are also accessible using
|
|
named attributes (for example, :func:`time.localtime` returns a
|
|
tuple-like object where the *year* is accessible either with an
|
|
index such as ``t[0]`` or with a named attribute like ``t.tm_year``).
|
|
|
|
A named tuple can be a built-in type such as :class:`time.struct_time`,
|
|
or it can be created with a regular class definition. A full featured
|
|
named tuple can also be created with the factory function
|
|
:func:`collections.namedtuple`. The latter approach automatically
|
|
provides extra features such as a self-documenting representation like
|
|
``Employee(name='jones', title='programmer')``.
|
|
|
|
namespace
|
|
The place where a variable is stored. Namespaces are implemented as
|
|
dictionaries. There are the local, global and built-in namespaces as well
|
|
as nested namespaces in objects (in methods). Namespaces support
|
|
modularity by preventing naming conflicts. For instance, the functions
|
|
:func:`__builtin__.open` and :func:`os.open` are distinguished by their
|
|
namespaces. Namespaces also aid readability and maintainability by making
|
|
it clear which module implements a function. For instance, writing
|
|
:func:`random.seed` or :func:`itertools.izip` makes it clear that those
|
|
functions are implemented by the :mod:`random` and :mod:`itertools`
|
|
modules, respectively.
|
|
|
|
nested scope
|
|
The ability to refer to a variable in an enclosing definition. For
|
|
instance, a function defined inside another function can refer to
|
|
variables in the outer function. Note that nested scopes work only for
|
|
reference and not for assignment which will always write to the innermost
|
|
scope. In contrast, local variables both read and write in the innermost
|
|
scope. Likewise, global variables read and write to the global namespace.
|
|
|
|
new-style class
|
|
Any class which inherits from :class:`object`. This includes all built-in
|
|
types like :class:`list` and :class:`dict`. Only new-style classes can
|
|
use Python's newer, versatile features like :attr:`__slots__`,
|
|
descriptors, properties, and :meth:`__getattribute__`.
|
|
|
|
More information can be found in :ref:`newstyle`.
|
|
|
|
object
|
|
Any data with state (attributes or value) and defined behavior
|
|
(methods). Also the ultimate base class of any :term:`new-style
|
|
class`.
|
|
|
|
positional argument
|
|
The arguments assigned to local names inside a function or method,
|
|
determined by the order in which they were given in the call. ``*`` is
|
|
used to either accept multiple positional arguments (when in the
|
|
definition), or pass several arguments as a list to a function. See
|
|
:term:`argument`.
|
|
|
|
Python 3000
|
|
Nickname for the next major Python version, 3.0 (coined long ago
|
|
when the release of version 3 was something in the distant future.) This
|
|
is also abbreviated "Py3k".
|
|
|
|
Pythonic
|
|
An idea or piece of code which closely follows the most common idioms
|
|
of the Python language, rather than implementing code using concepts
|
|
common to other languages. For example, a common idiom in Python is
|
|
to loop over all elements of an iterable using a :keyword:`for`
|
|
statement. Many other languages don't have this type of construct, so
|
|
people unfamiliar with Python sometimes use a numerical counter instead::
|
|
|
|
for i in range(len(food)):
|
|
print food[i]
|
|
|
|
As opposed to the cleaner, Pythonic method::
|
|
|
|
for piece in food:
|
|
print piece
|
|
|
|
reference count
|
|
The number of references to an object. When the reference count of an
|
|
object drops to zero, it is deallocated. Reference counting is
|
|
generally not visible to Python code, but it is a key element of the
|
|
:term:`CPython` implementation. The :mod:`sys` module defines a
|
|
:func:`getrefcount` function that programmers can call to return the
|
|
reference count for a particular object.
|
|
|
|
__slots__
|
|
A declaration inside a :term:`new-style class` that saves memory by
|
|
pre-declaring space for instance attributes and eliminating instance
|
|
dictionaries. Though popular, the technique is somewhat tricky to get
|
|
right and is best reserved for rare cases where there are large numbers of
|
|
instances in a memory-critical application.
|
|
|
|
sequence
|
|
An :term:`iterable` which supports efficient element access using integer
|
|
indices via the :meth:`__getitem__` special method and defines a
|
|
:meth:`len` method that returns the length of the sequence.
|
|
Some built-in sequence types are :class:`list`, :class:`str`,
|
|
:class:`tuple`, and :class:`unicode`. Note that :class:`dict` also
|
|
supports :meth:`__getitem__` and :meth:`__len__`, but is considered a
|
|
mapping rather than a sequence because the lookups use arbitrary
|
|
:term:`immutable` keys rather than integers.
|
|
|
|
slice
|
|
An object usually containing a portion of a :term:`sequence`. A slice is
|
|
created using the subscript notation, ``[]`` with colons between numbers
|
|
when several are given, such as in ``variable_name[1:3:5]``. The bracket
|
|
(subscript) notation uses :class:`slice` objects internally (or in older
|
|
versions, :meth:`__getslice__` and :meth:`__setslice__`).
|
|
|
|
special method
|
|
A method that is called implicitly by Python to execute a certain
|
|
operation on a type, such as addition. Such methods have names starting
|
|
and ending with double underscores. Special methods are documented in
|
|
:ref:`specialnames`.
|
|
|
|
statement
|
|
A statement is part of a suite (a "block" of code). A statement is either
|
|
an :term:`expression` or a one of several constructs with a keyword, such
|
|
as :keyword:`if`, :keyword:`while` or :keyword:`print`.
|
|
|
|
triple-quoted string
|
|
A string which is bound by three instances of either a quotation mark
|
|
(") or an apostrophe ('). While they don't provide any functionality
|
|
not available with single-quoted strings, they are useful for a number
|
|
of reasons. They allow you to include unescaped single and double
|
|
quotes within a string and they can span multiple lines without the
|
|
use of the continuation character, making them especially useful when
|
|
writing docstrings.
|
|
|
|
type
|
|
The type of a Python object determines what kind of object it is; every
|
|
object has a type. An object's type is accessible as its
|
|
:attr:`__class__` attribute or can be retrieved with ``type(obj)``.
|
|
|
|
view
|
|
The objects returned from :meth:`dict.viewkeys`, :meth:`dict.viewvalues`,
|
|
and :meth:`dict.viewitems` are called dictionary views. They are lazy
|
|
sequences that will see changes in the underlying dictionary. To force
|
|
the dictionary view to become a full list use ``list(dictview)``. See
|
|
:ref:`dict-views`.
|
|
|
|
virtual machine
|
|
A computer defined entirely in software. Python's virtual machine
|
|
executes the :term:`bytecode` emitted by the bytecode compiler.
|
|
|
|
Zen of Python
|
|
Listing of Python design principles and philosophies that are helpful in
|
|
understanding and using the language. The listing can be found by typing
|
|
"``import this``" at the interactive prompt.
|