Added documentation to type casting objects.

doc/advanced.rst

@@ -61,18 +61,18 @@ by the :func:`psycopg2.extensions.adapt()` function.
 
 The :meth:`cursor.execute()` method adapts its arguments to the
 :class:`psycopg2.extensions.ISQLQuote` protocol.  Objects that conform to this
-protocol expose a ``getquoted()`` method returning the SQL representation of
+protocol expose a :meth:`getquoted()` method returning the SQL representation
-the object as a string.
+of the object as a string.
 
 The easiest way to adapt an object to an SQL string is to register an adapter
 function via the :func:`psycopg2.extensions.register_adapter()` function.  The
 adapter function must take the value to be adapted as argument and return a
 conform object.  A convenient object is the :func:`psycopg2.extensions.AsIs`
-wrapper, whose ``getquoted()`` result is simply the ``str()``\ ingification of
+wrapper, whose :meth:`getquoted()` result is simply the ``str()``\ ing
-the wrapped object.
+conversion of the wrapped object.
 
-Example: mapping of a ``Point`` class into the ``point`` PostgreSQL geometric
+Example: mapping of a :data:`Point` class into the |point|_ PostgreSQL
-type::
+geometric type::
 
     from psycopg2.extensions import adapt, register_adapter, AsIs
 
@@ -89,6 +89,10 @@ type::
     curs.execute("INSERT INTO atable (apoint) VALUES (%s)",
                  (Point(1.23, 4.56),))
 
+
+.. |point| replace:: ``point``
+.. _point: http://www.postgresql.org/docs/8.4/static/datatype-geometric.html#AEN6084
+
 The above function call results in the SQL command::
 
     INSERT INTO atable (apoint) VALUES ((1.23, 4.56));
@@ -99,8 +103,8 @@ The above function call results in the SQL command::
 
 .. _type-casting-from-sql-to-python:
 
-Type casting of SQL types into Python values
+Type casting of SQL types into Python objects
---------------------------------------------
+---------------------------------------------
 
 PostgreSQL objects read from the database can be adapted to Python objects
 through an user-defined adapting function.  An adapter function takes two
@@ -111,13 +115,13 @@ previously defined ``Point`` class::
 
     def cast_point(value, curs):
         if value is not None:
-        	# Convert from (f1, f2) syntax using a regular expression.
+            # Convert from (f1, f2) syntax using a regular expression.
-            m = re.match("\((.*),(.*)\)", value) 
+            m = re.match(r"\(([^)]+),([^)]+)\)", value)
             if m:
                 return Point(float(m.group(1)), float(m.group(2)))
 
 To create a mapping from the PostgreSQL type (either standard or user-defined),
-its ``oid`` must be known. It can be retrieved either by the second column of
+its OID must be known. It can be retrieved either by the second column of
 the cursor description::
 
     curs.execute("SELECT NULL::point")
@@ -132,11 +136,11 @@ namespace for system objects is ``pg_catalog``)::
                  ON typnamespace = pg_namespace.oid
          WHERE typname = %(typename)s
            AND nspname = %(namespace)s""",
-                {'typename': 'point', 'namespace': 'pg_catalog'})
+        {'typename': 'point', 'namespace': 'pg_catalog'})
 
     point_oid = curs.fetchone()[0]
 
-After you know the object ``oid``, you must can and register the new type::
+After you know the object OID, you must can and register the new type::
 
     POINT = psycopg2.extensions.new_type((point_oid,), "POINT", cast_point)
     psycopg2.extensions.register_type(POINT)
@@ -144,7 +148,7 @@ After you know the object ``oid``, you must can and register the new type::
 The :func:`psycopg2.extensions.new_type()` function binds the object oids
 (more than one can be specified) to the adapter function.
 :func:`psycopg2.extensions.register_type()` completes the spell.  Conversion
-is automatically performed when a column whose type is a registered ``oid`` is
+is automatically performed when a column whose type is a registered OID is
 read::
 
     >>> curs.execute("SELECT '(10.2,20.3)'::point")

doc/extensions.rst

@@ -36,7 +36,167 @@ functionalities defined by the |DBAPI|.
     .. todo:: class lobject
 
 
-.. todo:: finish module extensions
+
+.. _sql-adaptation-objects:
+
+SQL adaptation protocol objects
+-------------------------------
+
+Psycopg provides a flexible system to adapt Python objects to the SQL syntax
+(inspired to the :pep:`246`), allowing serialization in PostgreSQL. See
+:ref:`adapting-new-types` for a detailed description.  The following objects
+deal with Python objects adaptation:
+
+.. function:: adapt(obj)
+
+    Return the SQL representation of :obj:`obj` as a string.  Raise a
+    :exc:`ProgrammingError` if how to adapt the object is unknown.  In order
+    to allow new objects to be adapted, register a new adapter for it using
+    the :func:`register_adapter` function.
+
+    The function is the entry point of the adaptation mechanism: it can be
+    used to write adapters for complex objects by recursively calling
+    :func:`adapt` on its components.
+
+.. function:: register_adapter(class, adapter)
+
+    Register a new adapter for the objects of class :data:`class`.
+
+    :data:`adapter` should be a function taking a single argument (the object
+    to adapt) and returning an object conforming the :class:`ISQLQuote`
+    protocol (e.g. exposing a :meth:`getquoted` method).  The :class:`AsIs` is
+    often useful for this task.
+
+    Once an object is registered, it can be safely used in SQL queries and by
+    the :func:`adapt` function.
+
+.. class:: ISQLQuote
+
+    Represents the SQL adaptation protocol. Objects conforming this protocol
+    should implement a :meth:`getquoted` method.
+
+    .. todo:: has Psycopg user ever to explicitely use this object?
+
+    .. todo::
+        what the ISQLQuote methods are for? In my understanding the
+        class is only used as symbol to dispatch adaptation and not to be
+        instantiated.
+
+.. class:: AsIs
+
+    Adapter conform to the :class:`ISQLQuote` protocol useful for objects
+    whose string representation is already valid as SQL representation.
+
+    .. method:: getquoted()
+
+        Return the ``str()`` conversion of the wrapped object. ::
+
+            >>> AsIs(42).getquoted()
+            '42'
+
+.. class:: QuotedString
+
+    Adapter conform to the :class:`ISQLQuote` protocol for string-like
+    objects.
+
+    .. method:: getquoted()
+
+        Return the string enclosed in single quotes.  Any single quote
+        appearing in the the string is escaped by doubling it according to SQL
+        string constants syntax.  Backslashes are escaped too.
+
+            >>> QuotedString(r"O'Reilly").getquoted()
+            "'O''Reilly'"
+
+.. class:: Binary
+
+    Adapter conform to the :class:`ISQLQuote` protocol for binary objects.
+
+    .. method:: getquoted()
+
+        Return the string enclosed in single quotes.  It performs the same
+        escaping of the :class:`QuotedString` adapter, plus it knows how to
+        escape non-printable chars.
+
+            >>> Binary("\x00\x08\x0F").getquoted()
+            "'\\\\000\\\\010\\\\017'"
+
+    .. todo::
+
+        this class is actually not importd in module extensions: I'd say this
+        is a bug.
+
+
+.. data:: Boolean
+.. data:: Float
+
+Specialized adapters for builtin objects.
+
+.. data:: DateFromPy
+.. data:: TimeFromPy
+.. data:: TimestampFromPy
+.. data:: IntervalFromPy
+
+Specialized adapters for Python datetime objects.
+
+.. data:: DateFromMx
+.. data:: TimeFromMx
+.. data:: TimestampFromMx
+.. data:: IntervalFromMx
+
+Specialized adapters for `mx.DateTime`_ objects.
+
+.. data:: adapters
+
+    Dictionary of the currently registered object adapters.  Use
+    :func:`register_adapter` to add an adapter for a new type.
+
+
+
+Database types casting functions
+--------------------------------
+
+These functions are used to manipulate type casters to convert from PostgreSQL
+types to Python objects.  See :ref:`type-casting-from-sql-to-python` for
+details.
+
+.. function:: new_type(oids, name, adapter)
+
+    Create a new type caster to convert from a PostgreSQL type to a Python
+    object.  The created object must be registered using
+    :func:`register_type` to be used.
+
+    :param oids: tuple of OIDs of the PostgreSQL type to convert.
+    :param name: the name of the new type adapter.
+    :param adapter: the adaptation function.
+
+    The object OID can be read from the :data:`cursor.description` or directly
+    from the PostgreSQL catalog.
+
+    :data:`adapter` should have signature ``fun(value, cur)`` where
+    ``value`` is the string representation returned by PostgreSQL and ``cur``
+    is the cursor from which data are read. In case of ``NULL``, ``value`` is
+    ``None``. The adapter should return the converted object.
+
+    See :ref:`type-casting-from-sql-to-python` for an usage example.
+
+.. function:: register_type(obj [, scope])
+
+    Register a type caster created using :func:`new_type`.
+
+    If :obj:`scope` is specified, it should be a :class:`connection` or a
+    :class:`cursor`: the type caster will be effective only limited to the
+    specified object.  Otherwise it will be globally registered.
+
+    .. todo:: Please confirm the above behaviour.
+
+.. data:: string_types
+
+    The global register of type casters.
+
+.. data:: binary_types
+
+    .. todo:: is this used?
 
 
 

doc/usage.rst

@@ -306,7 +306,14 @@ the SQL string that would be sent to the database.
     SQL doesn't allow an empty list in the IN operator, so your code should
     guard against empty tuples.
 
+  .. note::
 
+    In order to use the tuple adapter, your application must import the module
+    :mod:`psycopg2.extensions`.
+
+    .. todo:: is this a bug or a feature?
+
+  .. versionadded:: 2.0.6
 
 .. index::
     pair: Server side; Cursor