New python module gdb.printing, and new commands info pretty-printer,

enable pretty-printer, disable pretty-printer.
	* NEWS: Mention them.
	* data-directory/Makefile.in (PYTHON_FILES): Add gdb/printing.py,
	gdb/command/__init__.py, gdb/command/pretty_printers.py.
	* python/lib/gdb/__init__.py: Install pretty-printer commands.
	* python/lib/gdb/printing.py: New file.
	* python/lib/gdb/command/__init__.py: New file.
	* python/lib/gdb/command/pretty_printers.py: New file.

	doc/
	* gdb.texinfo (Pretty Printing): Expand into three sections,
	introduction, example, and commands.
	(Python API): Delete section Disabling Pretty-Printers, merge into
	Selecting Pretty-Printers.
	(Writing a Pretty-Printer): New section.  Move the pretty-printer
	example here, and reformat to match python coding style.  Add a second
	example using the gdb.printing module.
	(Python modules): Add gdb.printing.

	testsuite/
	* gdb.python/py-pp-maint.c: New file.
	* gdb.python/py-pp-maint.exp: New file.
	* gdb.python/py-pp-maint.py: New file.

gdb/testsuite/gdb.python/py-pp-maint.py

@@ -0,0 +1,74 @@
+# Copyright (C) 2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the GDB testsuite.  It tests python pretty
+# printers.
+
+import re
+import gdb.types
+import gdb.printing
+
+
+def lookup_function_lookup_test(val):
+    class PrintFunctionLookup(object):
+        def __init__(self, val):
+            self.val = val
+
+        def to_string(self):
+            return ("x=<" + str(self.val["x"]) +
+                    "> y=<" + str(self.val["y"]) + ">")
+
+    typename = gdb.types.get_basic_type(val.type).tag
+    # Note: typename could be None.
+    if typename == "function_lookup_test":
+        return PrintFunctionLookup(val)
+    return None
+
+
+class pp_s:
+    def __init__(self, val):
+        self.val = val
+
+    def to_string(self):
+        a = self.val["a"]
+        b = self.val["b"]
+        if a.address != b:
+            raise Exception("&a(%s) != b(%s)" % (str(a.address), str(b)))
+        return "a=<" + str(self.val["a"]) + "> b=<" + str(self.val["b"]) + ">"
+
+
+class pp_ss:
+    def __init__(self, val):
+        self.val = val
+
+    def to_string(self):
+        return "a=<" + str(self.val["a"]) + "> b=<" + str(self.val["b"]) + ">"
+
+
+def build_pretty_printer():
+    pp = gdb.printing.RegexpCollectionPrettyPrinter("pp-test")
+
+    pp.add_printer('struct s', '^struct s$', pp_s)
+    pp.add_printer('s', '^s$', pp_s)
+
+    # Use a lambda this time to exercise doing things this way.
+    pp.add_printer('struct ss', '^struct ss$', lambda val: pp_ss(val))
+    pp.add_printer('ss', '^ss$', lambda val: pp_ss(val))
+
+    return pp
+
+
+gdb.printing.register_pretty_printer(gdb, lookup_function_lookup_test)
+gdb.printing.register_pretty_printer(gdb, build_pretty_printer())