When referring to namespaces, always say "namespaces" instead of

"name spaces".

Inconsistency noted by Keith Briggs <keith.briggs@bt.com>.
This commit is contained in:
Fred Drake 2000-09-12 16:23:48 +00:00
parent 81cccb7563
commit 1349437e4c
4 changed files with 54 additions and 53 deletions

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@ -480,9 +480,9 @@ in \code{cmp_op[\var{opname}]}.
\begin{opcodedesc}{IMPORT_NAME}{namei} \begin{opcodedesc}{IMPORT_NAME}{namei}
Imports the module \code{co_names[\var{namei}]}. The module object is Imports the module \code{co_names[\var{namei}]}. The module object is
pushed onto the stack. The current name space is not affected: for a pushed onto the stack. The current namespace is not affected: for a
proper import statement, a subsequent \code{STORE_FAST} instruction proper import statement, a subsequent \code{STORE_FAST} instruction
modifies the name space. modifies the namespace.
\end{opcodedesc} \end{opcodedesc}
\begin{opcodedesc}{IMPORT_FROM}{namei} \begin{opcodedesc}{IMPORT_FROM}{namei}

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@ -227,7 +227,7 @@ class instances are callable if they have a \method{__call__()} method.
The arguments are a file name and two optional dictionaries. The The arguments are a file name and two optional dictionaries. The
file is parsed and evaluated as a sequence of Python statements file is parsed and evaluated as a sequence of Python statements
(similarly to a module) using the \var{globals} and \var{locals} (similarly to a module) using the \var{globals} and \var{locals}
dictionaries as global and local name space. If the \var{locals} dictionaries as global and local namespace. If the \var{locals}
dictionary is omitted it defaults to the \var{globals} dictionary. dictionary is omitted it defaults to the \var{globals} dictionary.
If both dictionaries are omitted, the expression is executed in the If both dictionaries are omitted, the expression is executed in the
environment where \function{execfile()} is called. The return value is environment where \function{execfile()} is called. The return value is

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@ -888,7 +888,7 @@ different object types.
The implementation adds two special read-only attributes: The implementation adds two special read-only attributes:
\code{\var{f}.func_code} is a function's \dfn{code \code{\var{f}.func_code} is a function's \dfn{code
object}\obindex{code} (see below) and \code{\var{f}.func_globals} is object}\obindex{code} (see below) and \code{\var{f}.func_globals} is
the dictionary used as the function's global name space (this is the the dictionary used as the function's global namespace (this is the
same as \code{\var{m}.__dict__} where \var{m} is the module in which same as \code{\var{m}.__dict__} where \var{m} is the module in which
the function \var{f} was defined). the function \var{f} was defined).

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@ -317,7 +317,7 @@ commands. This is similar to the \file{.profile} feature of the
This file is only read in interactive sessions, not when Python reads 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 commands from a script, and not when \file{/dev/tty} is given as the
explicit source of commands (which otherwise behaves like an explicit source of commands (which otherwise behaves like an
interactive session). It is executed in the same name space where interactive session). It is executed in the same namespace where
interactive commands are executed, so that objects that it defines or interactive commands are executed, so that objects that it defines or
imports can be used without qualification in the interactive session. imports can be used without qualification in the interactive session.
You can also change the prompts \code{sys.ps1} and \code{sys.ps2} in You can also change the prompts \code{sys.ps1} and \code{sys.ps2} in
@ -3236,24 +3236,24 @@ Pascal.
Before introducing classes, I first have to tell you something about Before introducing classes, I first have to tell you something about
Python's scope rules. Class definitions play some neat tricks with Python's scope rules. Class definitions play some neat tricks with
name spaces, and you need to know how scopes and name spaces work to namespaces, and you need to know how scopes and namespaces work to
fully understand what's going on. Incidentally, knowledge about this fully understand what's going on. Incidentally, knowledge about this
subject is useful for any advanced Python programmer. subject is useful for any advanced Python programmer.
Let's begin with some definitions. Let's begin with some definitions.
A \emph{name space} is a mapping from names to objects. Most name A \emph{namespace} is a mapping from names to objects. Most
spaces are currently implemented as Python dictionaries, but that's namespaces are currently implemented as Python dictionaries, but
normally not noticeable in any way (except for performance), and it that's normally not noticeable in any way (except for performance),
may change in the future. Examples of name spaces are: the set of and it may change in the future. Examples of namespaces are: the set
built-in names (functions such as \function{abs()}, and built-in exception of built-in names (functions such as \function{abs()}, and built-in
names); the global names in a module; and the local names in a exception names); the global names in a module; and the local names in
function invocation. In a sense the set of attributes of an object a function invocation. In a sense the set of attributes of an object
also form a name space. The important thing to know about name also form a namespace. The important thing to know about namespaces
spaces is that there is absolutely no relation between names in is that there is absolutely no relation between names in different
different name spaces; for instance, two different modules may both namespaces; for instance, two different modules may both define a
define a function ``maximize'' without confusion --- users of the function ``maximize'' without confusion --- users of the modules must
modules must prefix it with the module name. prefix it with the module name.
By the way, I use the word \emph{attribute} for any name following a By the way, I use the word \emph{attribute} for any name following a
dot --- for example, in the expression \code{z.real}, \code{real} is dot --- for example, in the expression \code{z.real}, \code{real} is
@ -3262,13 +3262,13 @@ names in modules are attribute references: in the expression
\code{modname.funcname}, \code{modname} is a module object and \code{modname.funcname}, \code{modname} is a module object and
\code{funcname} is an attribute of it. In this case there happens to \code{funcname} is an attribute of it. In this case there happens to
be a straightforward mapping between the module's attributes and the be a straightforward mapping between the module's attributes and the
global names defined in the module: they share the same name global names defined in the module: they share the same namespace!
space!\footnote{ \footnote{
Except for one thing. Module objects have a secret read-only Except for one thing. Module objects have a secret read-only
attribute called \code{__dict__} which returns the dictionary attribute called \member{__dict__} which returns the dictionary
used to implement the module's name space; the name used to implement the module's namespace; the name
\code{__dict__} is an attribute but not a global name. \member{__dict__} is an attribute but not a global name.
Obviously, using this violates the abstraction of name space Obviously, using this violates the abstraction of namespace
implementation, and should be restricted to things like implementation, and should be restricted to things like
post-mortem debuggers. post-mortem debuggers.
} }
@ -3280,54 +3280,54 @@ also be deleted with the \keyword{del} statement, e.g.
\samp{del modname.the_answer}. \samp{del modname.the_answer}.
Name spaces are created at different moments and have different Name spaces are created at different moments and have different
lifetimes. The name space containing the built-in names is created lifetimes. The namespace containing the built-in names is created
when the Python interpreter starts up, and is never deleted. The when the Python interpreter starts up, and is never deleted. The
global name space for a module is created when the module definition global namespace for a module is created when the module definition
is read in; normally, module name spaces also last until the is read in; normally, module namespaces also last until the
interpreter quits. The statements executed by the top-level interpreter quits. The statements executed by the top-level
invocation of the interpreter, either read from a script file or invocation of the interpreter, either read from a script file or
interactively, are considered part of a module called interactively, are considered part of a module called
\module{__main__}, so they have their own global name space. (The \module{__main__}, so they have their own global namespace. (The
built-in names actually also live in a module; this is called built-in names actually also live in a module; this is called
\module{__builtin__}.) \module{__builtin__}.)
The local name space for a function is created when the function is The local namespace for a function is created when the function is
called, and deleted when the function returns or raises an exception called, and deleted when the function returns or raises an exception
that is not handled within the function. (Actually, forgetting would that is not handled within the function. (Actually, forgetting would
be a better way to describe what actually happens.) Of course, be a better way to describe what actually happens.) Of course,
recursive invocations each have their own local name space. recursive invocations each have their own local namespace.
A \emph{scope} is a textual region of a Python program where a name space A \emph{scope} is a textual region of a Python program where a
is directly accessible. ``Directly accessible'' here means that an namespace is directly accessible. ``Directly accessible'' here means
unqualified reference to a name attempts to find the name in the name that an unqualified reference to a name attempts to find the name in
space. the namespace.
Although scopes are determined statically, they are used dynamically. Although scopes are determined statically, they are used dynamically.
At any time during execution, exactly three nested scopes are in use At any time during execution, exactly three nested scopes are in use
(i.e., exactly three name spaces are directly accessible): the (i.e., exactly three namespaces are directly accessible): the
innermost scope, which is searched first, contains the local names, innermost scope, which is searched first, contains the local names,
the middle scope, searched next, contains the current module's global the middle scope, searched next, contains the current module's global
names, and the outermost scope (searched last) is the name space names, and the outermost scope (searched last) is the namespace
containing built-in names. containing built-in names.
Usually, the local scope references the local names of the (textually) Usually, the local scope references the local names of the (textually)
current function. Outside of functions, the local scope references current function. Outside of functions, the local scope references
the same name space as the global scope: the module's name space. the same namespace as the global scope: the module's namespace.
Class definitions place yet another name space in the local scope. Class definitions place yet another namespace in the local scope.
It is important to realize that scopes are determined textually: the It is important to realize that scopes are determined textually: the
global scope of a function defined in a module is that module's name global scope of a function defined in a module is that module's
space, no matter from where or by what alias the function is called. namespace, no matter from where or by what alias the function is
On the other hand, the actual search for names is done dynamically, at called. On the other hand, the actual search for names is done
run time --- however, the language definition is evolving towards dynamically, at run time --- however, the language definition is
static name resolution, at ``compile'' time, so don't rely on dynamic evolving towards static name resolution, at ``compile'' time, so don't
name resolution! (In fact, local variables are already determined rely on dynamic name resolution! (In fact, local variables are
statically.) already determined statically.)
A special quirk of Python is that assignments always go into the A special quirk of Python is that assignments always go into the
innermost scope. Assignments do not copy data --- they just innermost scope. Assignments do not copy data --- they just
bind names to objects. The same is true for deletions: the statement bind names to objects. The same is true for deletions: the statement
\samp{del x} removes the binding of \code{x} from the name space \samp{del x} removes the binding of \code{x} from the namespace
referenced by the local scope. In fact, all operations that introduce referenced by the local scope. In fact, all operations that introduce
new names use the local scope: in particular, import statements and new names use the local scope: in particular, import statements and
function definitions bind the module or function name in the local function definitions bind the module or function name in the local
@ -3366,14 +3366,14 @@ inside a class normally have a peculiar form of argument list,
dictated by the calling conventions for methods --- again, this is dictated by the calling conventions for methods --- again, this is
explained later. explained later.
When a class definition is entered, a new name space is created, and When a class definition is entered, a new namespace is created, and
used as the local scope --- thus, all assignments to local variables used as the local scope --- thus, all assignments to local variables
go into this new name space. In particular, function definitions bind go into this new namespace. In particular, function definitions bind
the name of the new function here. the name of the new function here.
When a class definition is left normally (via the end), a \emph{class When a class definition is left normally (via the end), a \emph{class
object} is created. This is basically a wrapper around the contents object} is created. This is basically a wrapper around the contents
of the name space created by the class definition; we'll learn more of the namespace created by the class definition; we'll learn more
about class objects in the next section. The original local scope about class objects in the next section. The original local scope
(the one in effect just before the class definitions was entered) is (the one in effect just before the class definitions was entered) is
reinstated, and the class object is bound here to the class name given reinstated, and the class object is bound here to the class name given
@ -3387,7 +3387,7 @@ and instantiation.
\emph{Attribute references} use the standard syntax used for all \emph{Attribute references} use the standard syntax used for all
attribute references in Python: \code{obj.name}. Valid attribute attribute references in Python: \code{obj.name}. Valid attribute
names are all the names that were in the class's name space when the names are all the names that were in the class's namespace when the
class object was created. So, if the class definition looked like class object was created. So, if the class definition looked like
this: this:
@ -3766,9 +3766,10 @@ code that is byte-compiled together. The same restriction applies to
when referencing \code{__dict__} directly. when referencing \code{__dict__} directly.
Here's an example of a class that implements its own Here's an example of a class that implements its own
\code{__getattr__} and \code{__setattr__} methods and stores all \method{__getattr__()} and \method{__setattr__()} methods and stores
attributes in a private variable, in a way that works in Python 1.4 as all attributes in a private variable, in a way that works in all
well as in previous versions: versions of Python, including those available before this feature was
added:
\begin{verbatim} \begin{verbatim}
class VirtualAttributes: class VirtualAttributes: