Add the 'bool' type and its values 'False' and 'True', as described in

PEP 285.  Everything described in the PEP is here, and there is even
some documentation.  I had to fix 12 unit tests; all but one of these
were printing Boolean outcomes that changed from 0/1 to False/True.
(The exception is test_unicode.py, which did a type(x) == type(y)
style comparison.  I could've fixed that with a single line using
issubtype(x, type(y)), but instead chose to be explicit about those
places where a bool is expected.

Still to do: perhaps more documentation; change standard library
modules to return False/True from predicates.

3 files changed, 58 insertions, 13 deletions

diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index a2407d7..814b26b 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -77,6 +77,16 @@ def my_import(name):
   to \code{\var{function}(*\var{args}, **\var{keywords})}.
 \end{funcdesc}
 
+\begin{funcdesc}{bool}{x}
+  Convert a value to a Boolean, using the standard truth testing
+  procedure.  If \code{x} is false, this returns \code{False};
+  otherwise it returns \code{True}.  \code{bool} is also a class,
+  which is a subclass of \code{int}.  Class \code{bool} cannot be
+  subclassed further.  Its only instances are \code{False} and
+  \code{True}.
+\indexii{Boolean}{type}
+\end{funcdesc}
+
 \begin{funcdesc}{buffer}{object\optional{, offset\optional{, size}}}
   The \var{object} argument must be an object that supports the buffer
   call interface (such as strings, arrays, and buffers).  A new buffer
diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex
index 2bd6420..d63e4d5 100644
--- a/Doc/lib/libstdtypes.tex
+++ b/Doc/lib/libstdtypes.tex
@@ -2,10 +2,8 @@
 
 The following sections describe the standard types that are built into
 the interpreter.  These are the numeric types, sequence types, and
-several others, including types themselves.  There is no explicit
-Boolean type; use integers instead.
+several others, including types themselves.
 \indexii{built-in}{types}
-\indexii{Boolean}{type}
 
 Some operations are supported by several object types; in particular,
 all objects can be compared, tested for truth value, and converted to
@@ -30,6 +28,9 @@ The following values are considered false:
 \item	\code{None}
 	\withsubitem{(Built-in object)}{\ttindex{None}}
 
+\item	\code{False}
+	\withsubitem{(Built-in object)}{\ttindex{False}}
+
 \item	zero of any numeric type, for example, \code{0}, \code{0L},
         \code{0.0}, \code{0j}.
 
@@ -50,11 +51,12 @@ always true.
 \index{true}
 
 Operations and built-in functions that have a Boolean result always
-return \code{0} for false and \code{1} for true, unless otherwise
-stated.  (Important exception: the Boolean operations
-\samp{or}\opindex{or} and \samp{and}\opindex{and} always return one of
-their operands.)
-
+return \code{0} or \code{False} for false and \code{1} or \code{True}
+for true, unless otherwise stated.  (Important exception: the Boolean
+operations \samp{or}\opindex{or} and \samp{and}\opindex{and} always
+return one of their operands.)
+\index{False}
+\index{True}
 
 \subsection{Boolean Operations \label{boolean}}
 
@@ -68,7 +70,7 @@ These are the Boolean operations, ordered by ascending priority:
           {if \var{x} is false, then \var{x}, else \var{y}}{(1)}
   \hline
   \lineiii{not \var{x}}
-          {if \var{x} is false, then \code{1}, else \code{0}}{(2)}
+          {if \var{x} is false, then \code{True}, else \code{False}}{(2)}
 \end{tableiii}
 \opindex{and}
 \opindex{or}
@@ -161,8 +163,10 @@ only by sequence types (below).
 
 \subsection{Numeric Types \label{typesnumeric}}
 
-There are four numeric types: \dfn{plain integers}, \dfn{long integers},
+There are four distinct numeric types: \dfn{plain integers},
+\dfn{long integers}, 
 \dfn{floating point numbers}, and \dfn{complex numbers}.
+In addition, Booleans are a subtype of plain integers.
 Plain integers (also just called \dfn{integers})
 are implemented using \ctype{long} in C, which gives them at least 32
 bits of precision.  Long integers have unlimited precision.  Floating
@@ -170,6 +174,7 @@ point numbers are implemented using \ctype{double} in C.  All bets on
 their precision are off unless you happen to know the machine you are
 working with.
 \obindex{numeric}
+\obindex{Boolean}
 \obindex{integer}
 \obindex{long integer}
 \obindex{floating point}
@@ -1389,6 +1394,22 @@ special operations.  There is exactly one ellipsis object, named
 
 It is written as \code{Ellipsis}.
 
+\subsubsection{Boolean Values}
+
+Boolean values are the two constant objects \code{False} and
+\code{True}.  They are used to represent truth values (although other
+values can also be considered false or true).  In numeric contexts
+(for example when used as the argument to an arithmetic operator),
+they behave like the integers 0 and 1, respectively.  The built-in
+function \function{bool()} can be used to cast any value to a Boolean,
+if the value can be interpreted as a truth value (see section Truth
+Value Testing above).
+
+They are written as \code{False} and \code{True}, respectively.
+\index{False}
+\index{True}
+\indexii{Boolean}{values}
+
 
 \subsubsection{Internal Objects \label{typesinternal}}
 
diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex
index d355b69..2056a6c 100644
--- a/Doc/ref/ref3.tex
+++ b/Doc/ref/ref3.tex
@@ -162,7 +162,7 @@ complex numbers:
 These represent elements from the mathematical set of whole numbers.
 \obindex{integer}
 
-There are two types of integers:
+There are three types of integers:
 
 \begin{description}
 
@@ -187,6 +187,17 @@ represented in a variant of 2's complement which gives the illusion of
 an infinite string of sign bits extending to the left.
 \obindex{long integer}
 
+\item[Booleans]
+These represent the truth values False and True.  The two objects
+representing the values False and True are the only Boolean objects.
+The Boolean type is a subtype of plain integers, and Boolean values
+behave like the values 0 and 1, respectively, in almost all contexts,
+the exception being that when converted to a string, the strings
+\code{"False"} or \code{"True"} are returned, respectively.
+\obindex{Boolean}
+\ttindex{False}
+\ttindex{True}
+
 \end{description} % Integers
 
 The rules for integer representation are intended to give the most
@@ -222,6 +233,7 @@ and \code{z.imag}.
 
 \end{description} % Numbers
 
+
 \item[Sequences]
 These represent finite ordered sets indexed by non-negative numbers.
 The built-in function \function{len()}\bifuncindex{len} returns the
@@ -1074,8 +1086,10 @@ wrong hash bucket).
 \end{methoddesc}
 
 \begin{methoddesc}[object]{__nonzero__}{self}
-Called to implement truth value testing; should return \code{0} or
-\code{1}.  When this method is not defined, \method{__len__()} is
+Called to implement truth value testing, and the built-in operation
+\code{bool()}; should return \code{False} or \code{True}, or their
+integer equivalents \code{0} or \code{1}.
+When this method is not defined, \method{__len__()} is
 called, if it is defined (see below).  If a class defines neither
 \method{__len__()} nor \method{__nonzero__()}, all its instances are
 considered true.