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(python2.1-lib.info)pprint

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Data pretty printer
===================

Data pretty printer.  This module was written by Fred L. Drake, Jr.
<fdrake@acm.org>.
This manual section was written by Fred L. Drake, Jr. <fdrake@acm.org>.
The `pprint' module provides a capability to "pretty-print" arbitrary
Python data structures in a form which can be used as input to the
interpreter.  If the formatted structures include objects which are not
fundamental Python types, the representation may not be loadable.  This
may be the case if objects such as files, sockets, classes, or
instances are included, as well as many other builtin objects which are
not representable as Python constants.

The formatted representation keeps objects on a single line if it can,
and breaks them onto multiple lines if they don't fit within the
allowed width.  Construct `PrettyPrinter' objects explicitly if you
need to adjust the width constraint.

The `pprint' module defines one class:

`PrettyPrinter(...)'
     Construct a `PrettyPrinter' instance.  This constructor
     understands several keyword parameters.  An output stream may be
     set using the STREAM keyword; the only method used on the stream
     object is the file protocol's `write()' method.  If not specified,
     the `PrettyPrinter' adopts `sys.stdout'.  Three additional
     parameters may be used to control the formatted representation.
     The keywords are INDENT, DEPTH, and WIDTH.  The amount of
     indentation added for each recursive level is specified by INDENT;
     the default is one.  Other values can cause output to look a
     little odd, but can make nesting easier to spot.  The number of
     levels which may be printed is controlled by DEPTH; if the data
     structure being printed is too deep, the next contained level is
     replaced by `...'.  By default, there is no constraint on the
     depth of the objects being formatted.  The desired output width is
     constrained using the WIDTH parameter; the default is eighty
     characters.  If a structure cannot be formatted within the
     constrained width, a best effort will be made.

          >>> import pprint, sys
          >>> stuff = sys.path[:]
          >>> stuff.insert(0, stuff[:])
          >>> pp = pprint.PrettyPrinter(indent=4)
          >>> pp.pprint(stuff)
          [   [   '',
                  '/usr/local/lib/python1.5',
                  '/usr/local/lib/python1.5/test',
                  '/usr/local/lib/python1.5/sunos5',
                  '/usr/local/lib/python1.5/sharedmodules',
                  '/usr/local/lib/python1.5/tkinter'],
              '',
              '/usr/local/lib/python1.5',
              '/usr/local/lib/python1.5/test',
              '/usr/local/lib/python1.5/sunos5',
              '/usr/local/lib/python1.5/sharedmodules',
              '/usr/local/lib/python1.5/tkinter']
          >>>
          >>> import parser
          >>> tup = parser.ast2tuple(
          ...     parser.suite(open('pprint.py').read()))[1][1][1]
          >>> pp = pprint.PrettyPrinter(depth=6)
          >>> pp.pprint(tup)
          (266, (267, (307, (287, (288, (...))))))

The `PrettyPrinter' class supports several derivative functions:

`pformat(object)'
     Return the formatted representation of OBJECT as a string.  The
     default parameters for formatting are used.

`pprint(object[, stream])'
     Prints the formatted representation of OBJECT on STREAM, followed
     by a newline.  If STREAM is omitted, `sys.stdout' is used.  This
     may be used in the interactive interpreter instead of a `print'
     statement for inspecting values.  The default parameters for
     formatting are used.

          >>> stuff = sys.path[:]
          >>> stuff.insert(0, stuff)
          >>> pprint.pprint(stuff)
          [<Recursion on list with id=869440>,
           '',
           '/usr/local/lib/python1.5',
           '/usr/local/lib/python1.5/test',
           '/usr/local/lib/python1.5/sunos5',
           '/usr/local/lib/python1.5/sharedmodules',
           '/usr/local/lib/python1.5/tkinter']

`isreadable(object)'
     Determine if the formatted representation of OBJECT is "readable,"
     or can be used to reconstruct the value using `eval()' .  This
     always returns false for recursive objects.

          >>> pprint.isreadable(stuff)
          0

`isrecursive(object)'
     Determine if OBJECT requires a recursive representation.

One more support function is also defined:

`saferepr(object)'
     Return a string representation of OBJECT, protected against
     recursive data structures.  If the representation of OBJECT
     exposes a recursive entry, the recursive reference will be
     represented as `<Recursion on TYPENAME with id=NUMBER>'.  The
     representation is not otherwise formatted.

     >>> pprint.saferepr(stuff)
     "[<Recursion on list with id=682968>, '', '/usr/local/lib/python1.5', '/usr/loca
     l/lib/python1.5/test', '/usr/local/lib/python1.5/sunos5', '/usr/local/lib/python
     1.5/sharedmodules', '/usr/local/lib/python1.5/tkinter']"

PrettyPrinter Objects