#ifndef Py_ABSTRACTOBJECT_H

#define Py_ABSTRACTOBJECT_H

#ifdef __cplusplus

extern "C" {

#endif

#ifdef PY_SSIZE_T_CLEAN

#define PyObject_CallFunction _PyObject_CallFunction_SizeT

#define PyObject_CallMethod _PyObject_CallMethod_SizeT

#endif

/* Abstract Object Interface (many thanks to Jim Fulton) */

/*

   PROPOSAL: A Generic Python Object Interface for Python C Modules

Problem

  Python modules written in C that must access Python objects must do

  so through routines whose interfaces are described by a set of

  include files.  Unfortunately, these routines vary according to the

  object accessed.  To use these routines, the C programmer must check

  the type of the object being used and must call a routine based on

  the object type.  For example, to access an element of a sequence,

  the programmer must determine whether the sequence is a list or a

  tuple:

    if(is_tupleobject(o))

      e=gettupleitem(o,i)

    else if(is_listitem(o))

      e=getlistitem(o,i)

  If the programmer wants to get an item from another type of object

  that provides sequence behavior, there is no clear way to do it

  correctly.  

  The persistent programmer may peruse object.h and find that the

  _typeobject structure provides a means of invoking up to (currently

  about) 41 special operators.  So, for example, a routine can get an

  item from any object that provides sequence behavior. However, to

  use this mechanism, the programmer must make their code dependent on

  the current Python implementation.

  Also, certain semantics, especially memory management semantics, may

  differ by the type of object being used.  Unfortunately, these

  semantics are not clearly described in the current include files.

  An abstract interface providing more consistent semantics is needed. 

Proposal

  I propose the creation of a standard interface (with an associated

  library of routines and/or macros) for generically obtaining the

  services of Python objects.  This proposal can be viewed as one

  components of a Python C interface consisting of several components.

  From the viewpoint of C access to Python services, we have (as

  suggested by Guido in off-line discussions):

  - "Very high level layer": two or three functions that let you exec or

    eval arbitrary Python code given as a string in a module whose name is

    given, passing C values in and getting C values out using

    mkvalue/getargs style format strings.  This does not require the user

    to declare any variables of type "PyObject *".  This should be enough

    to write a simple application that gets Python code from the user,

    execs it, and returns the output or errors.  (Error handling must also

    be part of this API.)

  - "Abstract objects layer": which is the subject of this proposal.

    It has many functions operating on objects, and lest you do many

    things from C that you can also write in Python, without going

    through the Python parser.

  - "Concrete objects layer": This is the public type-dependent

    interface provided by the standard built-in types, such as floats,

    strings, and lists.  This interface exists and is currently

    documented by the collection of include files provided with the

    Python distributions.

  From the point of view of Python accessing services provided by C

  modules: 

  - "Python module interface": this interface consist of the basic

    routines used to define modules and their members.  Most of the

    current extensions-writing guide deals with this interface.

  - "Built-in object interface": this is the interface that a new

    built-in type must provide and the mechanisms and rules that a

    developer of a new built-in type must use and follow.

  This proposal is a "first-cut" that is intended to spur

  discussion. See especially the lists of notes.

  The Python C object interface will provide four protocols: object,

  numeric, sequence, and mapping.  Each protocol consists of a

  collection of related operations.  If an operation that is not

  provided by a particular type is invoked, then a standard exception,

  NotImplementedError is raised with a operation name as an argument.

  In addition, for convenience this interface defines a set of

  constructors for building objects of built-in types.  This is needed

  so new objects can be returned from C functions that otherwise treat

  objects generically.

Memory Management

  For all of the functions described in this proposal, if a function

  retains a reference to a Python object passed as an argument, then the

  function will increase the reference count of the object.  It is

  unnecessary for the caller to increase the reference count of an

  argument in anticipation of the object's retention.

  All Python objects returned from functions should be treated as new

  objects.  Functions that return objects assume that the caller will

  retain a reference and the reference count of the object has already

  been incremented to account for this fact.  A caller that does not

  retain a reference to an object that is returned from a function

  must decrement the reference count of the object (using

  DECREF(object)) to prevent memory leaks.

  Note that the behavior mentioned here is different from the current

  behavior for some objects (e.g. lists and tuples) when certain

  type-specific routines are called directly (e.g. setlistitem).  The

  proposed abstraction layer will provide a consistent memory

  management interface, correcting for inconsistent behavior for some

  built-in types.

Protocols

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/

/*  Object Protocol: */

     /* Implemented elsewhere:

     int PyObject_Print(PyObject *o, FILE *fp, int flags);

         Print an object, o, on file, fp.  Returns -1 on

	 error.  The flags argument is used to enable certain printing

	 options. The only option currently supported is Py_Print_RAW. 

         (What should be said about Py_Print_RAW?)	

       */

     /* Implemented elsewhere:

     int PyObject_HasAttrString(PyObject *o, char *attr_name);

         Returns 1 if o has the attribute attr_name, and 0 otherwise.

	 This is equivalent to the Python expression:

	 hasattr(o,attr_name). 

	 This function always succeeds.

       */

     /* Implemented elsewhere:

     PyObject* PyObject_GetAttrString(PyObject *o, char *attr_name);

	 Retrieve an attributed named attr_name form object o.

	 Returns the attribute value on success, or NULL on failure.

	 This is the equivalent of the Python expression: o.attr_name.

       */

     /* Implemented elsewhere:

     int PyObject_HasAttr(PyObject *o, PyObject *attr_name);

         Returns 1 if o has the attribute attr_name, and 0 otherwise.

	 This is equivalent to the Python expression:

	 hasattr(o,attr_name). 

	 This function always succeeds.

       */

     /* Implemented elsewhere:

     PyObject* PyObject_GetAttr(PyObject *o, PyObject *attr_name);

	 Retrieve an attributed named attr_name form object o.

	 Returns the attribute value on success, or NULL on failure.

	 This is the equivalent of the Python expression: o.attr_name.

       */

     /* Implemented elsewhere:

     int PyObject_SetAttrString(PyObject *o, char *attr_name, PyObject *v);

	 Set the value of the attribute named attr_name, for object o,

	 to the value, v. Returns -1 on failure.  This is

	 the equivalent of the Python statement: o.attr_name=v.

       */

     /* Implemented elsewhere:

     int PyObject_SetAttr(PyObject *o, PyObject *attr_name, PyObject *v);

	 Set the value of the attribute named attr_name, for object o,

	 to the value, v. Returns -1 on failure.  This is

	 the equivalent of the Python statement: o.attr_name=v.

       */

     /* implemented as a macro:

     int PyObject_DelAttrString(PyObject *o, char *attr_name);

	 Delete attribute named attr_name, for object o. Returns

	 -1 on failure.  This is the equivalent of the Python

	 statement: del o.attr_name.

       */

#define  PyObject_DelAttrString(O,A) PyObject_SetAttrString((O),(A),NULL)

     /* implemented as a macro:

     int PyObject_DelAttr(PyObject *o, PyObject *attr_name);

	 Delete attribute named attr_name, for object o. Returns -1

	 on failure.  This is the equivalent of the Python

	 statement: del o.attr_name.

       */

#define  PyObject_DelAttr(O,A) PyObject_SetAttr((O),(A),NULL)

     PyAPI_FUNC(int) PyObject_Cmp(PyObject *o1, PyObject *o2, int *result);

       /*

	 Compare the values of o1 and o2 using a routine provided by

	 o1, if one exists, otherwise with a routine provided by o2.

	 The result of the comparison is returned in result.  Returns

	 -1 on failure.  This is the equivalent of the Python

	 statement: result=cmp(o1,o2).

       */

     /* Implemented elsewhere:

     int PyObject_Compare(PyObject *o1, PyObject *o2);

	 Compare the values of o1 and o2 using a routine provided by

	 o1, if one exists, otherwise with a routine provided by o2.

	 Returns the result of the comparison on success.  On error,

	 the value returned is undefined. This is equivalent to the

	 Python expression: cmp(o1,o2).

       */

     /* Implemented elsewhere:

     PyObject *PyObject_Repr(PyObject *o);

	 Compute the string representation of object, o.  Returns the

	 string representation on success, NULL on failure.  This is

	 the equivalent of the Python expression: repr(o).

	 Called by the repr() built-in function and by reverse quotes.

       */

     /* Implemented elsewhere:

     PyObject *PyObject_Str(PyObject *o);

	 Compute the string representation of object, o.  Returns the

	 string representation on success, NULL on failure.  This is

	 the equivalent of the Python expression: str(o).)

	 Called by the str() built-in function and by the print

	 statement.

       */

     /* Implemented elsewhere:

     PyObject *PyObject_Unicode(PyObject *o);

	 Compute the unicode representation of object, o.  Returns the

	 unicode representation on success, NULL on failure.  This is

	 the equivalent of the Python expression: unistr(o).)

	 Called by the unistr() built-in function.

       */

       /* Declared elsewhere

     PyAPI_FUNC(int) PyCallable_Check(PyObject *o);

	 Determine if the object, o, is callable.  Return 1 if the

	 object is callable and 0 otherwise.

	 This function always succeeds.

       */

     PyAPI_FUNC(PyObject *) PyObject_Call(PyObject *callable_object,

					 PyObject *args, PyObject *kw);

       /*

	 Call a callable Python object, callable_object, with

	 arguments and keywords arguments.  The 'args' argument can not be

	 NULL, but the 'kw' argument can be NULL.

       */

     PyAPI_FUNC(PyObject *) PyObject_CallObject(PyObject *callable_object,

                                               PyObject *args);

       /*

	 Call a callable Python object, callable_object, with

	 arguments given by the tuple, args.  If no arguments are

	 needed, then args may be NULL.  Returns the result of the

	 call on success, or NULL on failure.  This is the equivalent

	 of the Python expression: apply(o,args).

       */

     PyAPI_FUNC(PyObject *) PyObject_CallFunction(PyObject *callable_object,

                                                 char *format, ...);

       /*

	 Call a callable Python object, callable_object, with a

	 variable number of C arguments. The C arguments are described

	 using a mkvalue-style format string. The format may be NULL,

	 indicating that no arguments are provided.  Returns the

	 result of the call on success, or NULL on failure.  This is

	 the equivalent of the Python expression: apply(o,args).

       */

     PyAPI_FUNC(PyObject *) PyObject_CallMethod(PyObject *o, char *m,

                                               char *format, ...);

       /*

	 Call the method named m of object o with a variable number of

	 C arguments.  The C arguments are described by a mkvalue

	 format string.  The format may be NULL, indicating that no

	 arguments are provided. Returns the result of the call on

	 success, or NULL on failure.  This is the equivalent of the

	 Python expression: o.method(args).

       */

     PyAPI_FUNC(PyObject *) _PyObject_CallFunction_SizeT(PyObject *callable,

							 char *format, ...);

     PyAPI_FUNC(PyObject *) _PyObject_CallMethod_SizeT(PyObject *o,

						       char *name,

						       char *format, ...);

     PyAPI_FUNC(PyObject *) PyObject_CallFunctionObjArgs(PyObject *callable,

                                                        ...);

       /*

	 Call a callable Python object, callable_object, with a

	 variable number of C arguments.  The C arguments are provided

	 as PyObject * values, terminated by a NULL.  Returns the

	 result of the call on success, or NULL on failure.  This is

	 the equivalent of the Python expression: apply(o,args).

       */

     PyAPI_FUNC(PyObject *) PyObject_CallMethodObjArgs(PyObject *o,

                                                      PyObject *m, ...);

       /*

	 Call the method named m of object o with a variable number of

	 C arguments.  The C arguments are provided as PyObject *

	 values, terminated by NULL.  Returns the result of the call

	 on success, or NULL on failure.  This is the equivalent of

	 the Python expression: o.method(args).

       */

     /* Implemented elsewhere:

     long PyObject_Hash(PyObject *o);

         Compute and return the hash, hash_value, of an object, o.  On

	 failure, return -1.  This is the equivalent of the Python

	 expression: hash(o).

       */

     /* Implemented elsewhere:

     int PyObject_IsTrue(PyObject *o);

	 Returns 1 if the object, o, is considered to be true, 0 if o is

	 considered to be false and -1 on failure. This is equivalent to the

	 Python expression: not not o

       */

     /* Implemented elsewhere:

     int PyObject_Not(PyObject *o);

	 Returns 0 if the object, o, is considered to be true, 1 if o is

	 considered to be false and -1 on failure. This is equivalent to the

	 Python expression: not o

       */

     PyAPI_FUNC(PyObject *) PyObject_Type(PyObject *o);

       /*

	 On success, returns a type object corresponding to the object

	 type of object o. On failure, returns NULL.  This is

	 equivalent to the Python expression: type(o).

       */

     PyAPI_FUNC(Py_ssize_t) PyObject_Size(PyObject *o);

       /*

         Return the size of object o.  If the object, o, provides

	 both sequence and mapping protocols, the sequence size is

	 returned. On error, -1 is returned.  This is the equivalent

	 to the Python expression: len(o).

       */

       /* For DLL compatibility */

#undef PyObject_Length

     PyAPI_FUNC(Py_ssize_t) PyObject_Length(PyObject *o);

#define PyObject_Length PyObject_Size

     PyAPI_FUNC(Py_ssize_t) _PyObject_LengthHint(PyObject *o);

       /*

         Return the size of object o.  If the object, o, provides

	 both sequence and mapping protocols, the sequence size is

	 returned. On error, -1 is returned.  If the object provides

	 a __length_hint__() method, its value is returned.  This is an

	 internal undocumented API provided for performance reasons;

	 for compatibility, don't use it outside the core.  This is the

	 equivalent to the Python expression: 

		try:

			return len(o)

		except (AttributeError, TypeError):

			exc_type, exc_value, exc_tb = sys.exc_info()

			try:

				return o.__length_hint__()

			except:

				pass

			raise exc_type, exc_value, exc_tb

       */

     PyAPI_FUNC(PyObject *) PyObject_GetItem(PyObject *o, PyObject *key);

       /*

	 Return element of o corresponding to the object, key, or NULL

	 on failure. This is the equivalent of the Python expression:

	 o[key].

       */

     PyAPI_FUNC(int) PyObject_SetItem(PyObject *o, PyObject *key, PyObject *v);

       /*

	 Map the object, key, to the value, v.  Returns

	 -1 on failure.  This is the equivalent of the Python

	 statement: o[key]=v.

       */

     PyAPI_FUNC(int) PyObject_DelItemString(PyObject *o, char *key);

       /*

         Remove the mapping for object, key, from the object *o.

         Returns -1 on failure.  This is equivalent to

         the Python statement: del o[key].

       */

     PyAPI_FUNC(int) PyObject_DelItem(PyObject *o, PyObject *key);

       /*

	 Delete the mapping for key from *o.  Returns -1 on failure.

	 This is the equivalent of the Python statement: del o[key].

       */

     PyAPI_FUNC(int) PyObject_AsCharBuffer(PyObject *obj,

					  const char **buffer,

					  Py_ssize_t *buffer_len);

       /* 

	  Takes an arbitrary object which must support the (character,

	  single segment) buffer interface and returns a pointer to a

	  read-only memory location useable as character based input

	  for subsequent processing.

	  0 is returned on success.  buffer and buffer_len are only

	  set in case no error occurs. Otherwise, -1 is returned and

	  an exception set.

       */

     PyAPI_FUNC(int) PyObject_CheckReadBuffer(PyObject *obj);

      /*  

	  Checks whether an arbitrary object supports the (character,

	  single segment) buffer interface.  Returns 1 on success, 0

	  on failure.

      */

     PyAPI_FUNC(int) PyObject_AsReadBuffer(PyObject *obj,

					  const void **buffer,

					  Py_ssize_t *buffer_len);

       /* 

	  Same as PyObject_AsCharBuffer() except that this API expects

	  (readable, single segment) buffer interface and returns a

	  pointer to a read-only memory location which can contain

	  arbitrary data.

	  0 is returned on success.  buffer and buffer_len are only

	  set in case no error occurrs.  Otherwise, -1 is returned and

	  an exception set.

       */