| #ifndef Py_OBJECT_H |
| #define Py_OBJECT_H |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| /*********************************************************** |
| Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam, |
| The Netherlands. |
| |
| All Rights Reserved |
| |
| Permission to use, copy, modify, and distribute this software and its |
| documentation for any purpose and without fee is hereby granted, |
| provided that the above copyright notice appear in all copies and that |
| both that copyright notice and this permission notice appear in |
| supporting documentation, and that the names of Stichting Mathematisch |
| Centrum or CWI or Corporation for National Research Initiatives or |
| CNRI not be used in advertising or publicity pertaining to |
| distribution of the software without specific, written prior |
| permission. |
| |
| While CWI is the initial source for this software, a modified version |
| is made available by the Corporation for National Research Initiatives |
| (CNRI) at the Internet address ftp://ftp.python.org. |
| |
| STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH |
| REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF |
| MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH |
| CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL |
| DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
| PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER |
| TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR |
| PERFORMANCE OF THIS SOFTWARE. |
| |
| ******************************************************************/ |
| |
| /* Object and type object interface */ |
| |
| /* |
| 123456789-123456789-123456789-123456789-123456789-123456789-123456789-12 |
| |
| Objects are structures allocated on the heap. Special rules apply to |
| the use of objects to ensure they are properly garbage-collected. |
| Objects are never allocated statically or on the stack; they must be |
| accessed through special macros and functions only. (Type objects are |
| exceptions to the first rule; the standard types are represented by |
| statically initialized type objects.) |
| |
| An object has a 'reference count' that is increased or decreased when a |
| pointer to the object is copied or deleted; when the reference count |
| reaches zero there are no references to the object left and it can be |
| removed from the heap. |
| |
| An object has a 'type' that determines what it represents and what kind |
| of data it contains. An object's type is fixed when it is created. |
| Types themselves are represented as objects; an object contains a |
| pointer to the corresponding type object. The type itself has a type |
| pointer pointing to the object representing the type 'type', which |
| contains a pointer to itself!). |
| |
| Objects do not float around in memory; once allocated an object keeps |
| the same size and address. Objects that must hold variable-size data |
| can contain pointers to variable-size parts of the object. Not all |
| objects of the same type have the same size; but the size cannot change |
| after allocation. (These restrictions are made so a reference to an |
| object can be simply a pointer -- moving an object would require |
| updating all the pointers, and changing an object's size would require |
| moving it if there was another object right next to it.) |
| |
| Objects are always accessed through pointers of the type 'PyObject *'. |
| The type 'PyObject' is a structure that only contains the reference count |
| and the type pointer. The actual memory allocated for an object |
| contains other data that can only be accessed after casting the pointer |
| to a pointer to a longer structure type. This longer type must start |
| with the reference count and type fields; the macro PyObject_HEAD should be |
| used for this (to accomodate for future changes). The implementation |
| of a particular object type can cast the object pointer to the proper |
| type and back. |
| |
| A standard interface exists for objects that contain an array of items |
| whose size is determined when the object is allocated. |
| |
| 123456789-123456789-123456789-123456789-123456789-123456789-123456789-12 |
| */ |
| |
| #ifdef Py_DEBUG |
| |
| /* Turn on heavy reference debugging */ |
| #define Py_TRACE_REFS |
| |
| /* Turn on reference counting */ |
| #define Py_REF_DEBUG |
| |
| #endif /* Py_DEBUG */ |
| |
| #ifdef Py_TRACE_REFS |
| #define PyObject_HEAD \ |
| struct _object *_ob_next, *_ob_prev; \ |
| int ob_refcnt; \ |
| struct _typeobject *ob_type; |
| #define PyObject_HEAD_INIT(type) 0, 0, 1, type, |
| #else /* !Py_TRACE_REFS */ |
| #define PyObject_HEAD \ |
| int ob_refcnt; \ |
| struct _typeobject *ob_type; |
| #define PyObject_HEAD_INIT(type) 1, type, |
| #endif /* !Py_TRACE_REFS */ |
| |
| #define PyObject_VAR_HEAD \ |
| PyObject_HEAD \ |
| int ob_size; /* Number of items in variable part */ |
| |
| typedef struct _object { |
| PyObject_HEAD |
| } PyObject; |
| |
| typedef struct { |
| PyObject_VAR_HEAD |
| } varobject; |
| |
| |
| /* |
| 123456789-123456789-123456789-123456789-123456789-123456789-123456789-12 |
| |
| Type objects contain a string containing the type name (to help somewhat |
| in debugging), the allocation parameters (see newobj() and newvarobj()), |
| and methods for accessing objects of the type. Methods are optional,a |
| nil pointer meaning that particular kind of access is not available for |
| this type. The Py_DECREF() macro uses the tp_dealloc method without |
| checking for a nil pointer; it should always be implemented except if |
| the implementation can guarantee that the reference count will never |
| reach zero (e.g., for type objects). |
| |
| NB: the methods for certain type groups are now contained in separate |
| method blocks. |
| */ |
| |
| typedef PyObject * (*unaryfunc) Py_PROTO((PyObject *)); |
| typedef PyObject * (*binaryfunc) Py_PROTO((PyObject *, PyObject *)); |
| typedef PyObject * (*ternaryfunc) Py_PROTO((PyObject *, PyObject *, PyObject *)); |
| typedef int (*inquiry) Py_PROTO((PyObject *)); |
| typedef int (*coercion) Py_PROTO((PyObject **, PyObject **)); |
| typedef PyObject *(*intargfunc) Py_PROTO((PyObject *, int)); |
| typedef PyObject *(*intintargfunc) Py_PROTO((PyObject *, int, int)); |
| typedef int(*intobjargproc) Py_PROTO((PyObject *, int, PyObject *)); |
| typedef int(*intintobjargproc) Py_PROTO((PyObject *, int, int, PyObject *)); |
| typedef int(*objobjargproc) Py_PROTO((PyObject *, PyObject *, PyObject *)); |
| typedef int (*getreadbufferproc) Py_PROTO((PyObject *, int, void **)); |
| typedef int (*getwritebufferproc) Py_PROTO((PyObject *, int, void **)); |
| typedef int (*getsegcountproc) Py_PROTO((PyObject *, int *)); |
| |
| typedef struct { |
| binaryfunc nb_add; |
| binaryfunc nb_subtract; |
| binaryfunc nb_multiply; |
| binaryfunc nb_divide; |
| binaryfunc nb_remainder; |
| binaryfunc nb_divmod; |
| ternaryfunc nb_power; |
| unaryfunc nb_negative; |
| unaryfunc nb_positive; |
| unaryfunc nb_absolute; |
| inquiry nb_nonzero; |
| unaryfunc nb_invert; |
| binaryfunc nb_lshift; |
| binaryfunc nb_rshift; |
| binaryfunc nb_and; |
| binaryfunc nb_xor; |
| binaryfunc nb_or; |
| coercion nb_coerce; |
| unaryfunc nb_int; |
| unaryfunc nb_long; |
| unaryfunc nb_float; |
| unaryfunc nb_oct; |
| unaryfunc nb_hex; |
| } PyNumberMethods; |
| |
| typedef struct { |
| inquiry sq_length; |
| binaryfunc sq_concat; |
| intargfunc sq_repeat; |
| intargfunc sq_item; |
| intintargfunc sq_slice; |
| intobjargproc sq_ass_item; |
| intintobjargproc sq_ass_slice; |
| } PySequenceMethods; |
| |
| typedef struct { |
| inquiry mp_length; |
| binaryfunc mp_subscript; |
| objobjargproc mp_ass_subscript; |
| } PyMappingMethods; |
| |
| typedef struct { |
| getreadbufferproc bf_getreadbuffer; |
| getwritebufferproc bf_getwritebuffer; |
| getsegcountproc bf_getsegcount; |
| } PyBufferProcs; |
| |
| |
| typedef void (*destructor) Py_PROTO((PyObject *)); |
| typedef int (*printfunc) Py_PROTO((PyObject *, FILE *, int)); |
| typedef PyObject *(*getattrfunc) Py_PROTO((PyObject *, char *)); |
| typedef PyObject *(*getattrofunc) Py_PROTO((PyObject *, PyObject *)); |
| typedef int (*setattrfunc) Py_PROTO((PyObject *, char *, PyObject *)); |
| typedef int (*setattrofunc) Py_PROTO((PyObject *, PyObject *, PyObject *)); |
| typedef int (*cmpfunc) Py_PROTO((PyObject *, PyObject *)); |
| typedef PyObject *(*reprfunc) Py_PROTO((PyObject *)); |
| typedef long (*hashfunc) Py_PROTO((PyObject *)); |
| |
| typedef struct _typeobject { |
| PyObject_VAR_HEAD |
| char *tp_name; /* For printing */ |
| int tp_basicsize, tp_itemsize; /* For allocation */ |
| |
| /* Methods to implement standard operations */ |
| |
| destructor tp_dealloc; |
| printfunc tp_print; |
| getattrfunc tp_getattr; |
| setattrfunc tp_setattr; |
| cmpfunc tp_compare; |
| reprfunc tp_repr; |
| |
| /* Method suites for standard classes */ |
| |
| PyNumberMethods *tp_as_number; |
| PySequenceMethods *tp_as_sequence; |
| PyMappingMethods *tp_as_mapping; |
| |
| /* More standard operations (at end for binary compatibility) */ |
| |
| hashfunc tp_hash; |
| ternaryfunc tp_call; |
| reprfunc tp_str; |
| getattrofunc tp_getattro; |
| setattrofunc tp_setattro; |
| |
| /* Functions to access object as input/output buffer */ |
| PyBufferProcs *tp_as_buffer; |
| |
| /* Space for future expansion */ |
| long tp_xxx4; |
| |
| char *tp_doc; /* Documentation string */ |
| |
| #ifdef COUNT_ALLOCS |
| /* these must be last */ |
| int tp_alloc; |
| int tp_free; |
| int tp_maxalloc; |
| struct _typeobject *tp_next; |
| #endif |
| } PyTypeObject; |
| |
| extern DL_IMPORT(PyTypeObject) PyType_Type; /* The type of type objects */ |
| |
| #define PyType_Check(op) ((op)->ob_type == &PyType_Type) |
| |
| /* Generic operations on objects */ |
| extern int PyObject_Print Py_PROTO((PyObject *, FILE *, int)); |
| extern PyObject * PyObject_Repr Py_PROTO((PyObject *)); |
| extern PyObject * PyObject_Str Py_PROTO((PyObject *)); |
| extern int PyObject_Compare Py_PROTO((PyObject *, PyObject *)); |
| extern PyObject *PyObject_GetAttrString Py_PROTO((PyObject *, char *)); |
| extern int PyObject_SetAttrString Py_PROTO((PyObject *, char *, PyObject *)); |
| extern int PyObject_HasAttrString Py_PROTO((PyObject *, char *)); |
| extern PyObject *PyObject_GetAttr Py_PROTO((PyObject *, PyObject *)); |
| extern int PyObject_SetAttr Py_PROTO((PyObject *, PyObject *, PyObject *)); |
| extern long PyObject_Hash Py_PROTO((PyObject *)); |
| extern int PyObject_IsTrue Py_PROTO((PyObject *)); |
| extern int PyCallable_Check Py_PROTO((PyObject *)); |
| extern int PyNumber_Coerce Py_PROTO((PyObject **, PyObject **)); |
| |
| /* Flag bits for printing: */ |
| #define Py_PRINT_RAW 1 /* No string quotes etc. */ |
| |
| /* |
| 123456789-123456789-123456789-123456789-123456789-123456789-123456789-12 |
| |
| The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement |
| reference counts. Py_DECREF calls the object's deallocator function; for |
| objects that don't contain references to other objects or heap memory |
| this can be the standard function free(). Both macros can be used |
| whereever a void expression is allowed. The argument shouldn't be a |
| NIL pointer. The macro _Py_NewReference(op) is used only to initialize |
| reference counts to 1; it is defined here for convenience. |
| |
| We assume that the reference count field can never overflow; this can |
| be proven when the size of the field is the same as the pointer size |
| but even with a 16-bit reference count field it is pretty unlikely so |
| we ignore the possibility. (If you are paranoid, make it a long.) |
| |
| Type objects should never be deallocated; the type pointer in an object |
| is not considered to be a reference to the type object, to save |
| complications in the deallocation function. (This is actually a |
| decision that's up to the implementer of each new type so if you want, |
| you can count such references to the type object.) |
| |
| *** WARNING*** The Py_DECREF macro must have a side-effect-free argument |
| since it may evaluate its argument multiple times. (The alternative |
| would be to mace it a proper function or assign it to a global temporary |
| variable first, both of which are slower; and in a multi-threaded |
| environment the global variable trick is not safe.) |
| */ |
| |
| #ifdef Py_TRACE_REFS |
| #ifndef Py_REF_DEBUG |
| #define Py_REF_DEBUG |
| #endif |
| #endif |
| |
| #ifdef Py_TRACE_REFS |
| extern void _Py_Dealloc Py_PROTO((PyObject *)); |
| extern void _Py_NewReference Py_PROTO((PyObject *)); |
| extern void _Py_ForgetReference Py_PROTO((PyObject *)); |
| extern void _Py_PrintReferences Py_PROTO((FILE *)); |
| #endif |
| |
| #ifndef Py_TRACE_REFS |
| #ifdef COUNT_ALLOCS |
| #define _Py_Dealloc(op) ((op)->ob_type->tp_free++, (*(op)->ob_type->tp_dealloc)((PyObject *)(op))) |
| #define _Py_ForgetReference(op) ((op)->ob_type->tp_free++) |
| #else /* !COUNT_ALLOCS */ |
| #define _Py_Dealloc(op) (*(op)->ob_type->tp_dealloc)((PyObject *)(op)) |
| #define _Py_ForgetReference(op) /*empty*/ |
| #endif /* !COUNT_ALLOCS */ |
| #endif /* !Py_TRACE_REFS */ |
| |
| #ifdef COUNT_ALLOCS |
| extern void inc_count Py_PROTO((PyTypeObject *)); |
| #endif |
| |
| #ifdef Py_REF_DEBUG |
| |
| extern long _Py_RefTotal; |
| |
| #ifndef Py_TRACE_REFS |
| #ifdef COUNT_ALLOCS |
| #define _Py_NewReference(op) (inc_count((op)->ob_type), _Py_RefTotal++, (op)->ob_refcnt = 1) |
| #else |
| #define _Py_NewReference(op) (_Py_RefTotal++, (op)->ob_refcnt = 1) |
| #endif |
| #endif /* !Py_TRACE_REFS */ |
| |
| #define Py_INCREF(op) (_Py_RefTotal++, (op)->ob_refcnt++) |
| #define Py_DECREF(op) \ |
| if (--_Py_RefTotal, --(op)->ob_refcnt != 0) \ |
| ; \ |
| else \ |
| _Py_Dealloc(op) |
| #else /* !Py_REF_DEBUG */ |
| |
| #ifdef COUNT_ALLOCS |
| #define _Py_NewReference(op) (inc_count((op)->ob_type), (op)->ob_refcnt = 1) |
| #else |
| #define _Py_NewReference(op) ((op)->ob_refcnt = 1) |
| #endif |
| |
| #define Py_INCREF(op) ((op)->ob_refcnt++) |
| #define Py_DECREF(op) \ |
| if (--(op)->ob_refcnt != 0) \ |
| ; \ |
| else \ |
| _Py_Dealloc(op) |
| #endif /* !Py_REF_DEBUG */ |
| |
| /* Macros to use in case the object pointer may be NULL: */ |
| |
| #define Py_XINCREF(op) if ((op) == NULL) ; else Py_INCREF(op) |
| #define Py_XDECREF(op) if ((op) == NULL) ; else Py_DECREF(op) |
| |
| /* Definition of NULL, so you don't have to include <stdio.h> */ |
| |
| #ifndef NULL |
| #define NULL 0 |
| #endif |
| |
| |
| /* |
| _Py_NoneStruct is an object of undefined type which can be used in contexts |
| where NULL (nil) is not suitable (since NULL often means 'error'). |
| |
| Don't forget to apply Py_INCREF() when returning this value!!! |
| */ |
| |
| extern DL_IMPORT(PyObject) _Py_NoneStruct; /* Don't use this directly */ |
| |
| #define Py_None (&_Py_NoneStruct) |
| |
| |
| /* |
| A common programming style in Python requires the forward declaration |
| of static, initialized structures, e.g. for a type object that is used |
| by the functions whose address must be used in the initializer. |
| Some compilers (notably SCO ODT 3.0, I seem to remember early AIX as |
| well) botch this if you use the static keyword for both declarations |
| (they allocate two objects, and use the first, uninitialized one until |
| the second declaration is encountered). Therefore, the forward |
| declaration should use the 'forwardstatic' keyword. This expands to |
| static on most systems, but to extern on a few. The actual storage |
| and name will still be static because the second declaration is |
| static, so no linker visible symbols will be generated. (Standard C |
| compilers take offense to the extern forward declaration of a static |
| object, so I can't just put extern in all cases. :-( ) |
| */ |
| |
| #ifdef BAD_STATIC_FORWARD |
| #define staticforward extern |
| #ifdef __SC__ |
| #define statichere |
| #else |
| #define statichere static |
| #endif /* __SC__ */ |
| #else /* !BAD_STATIC_FORWARD */ |
| #define staticforward static |
| #define statichere static |
| #endif /* !BAD_STATIC_FORWARD */ |
| |
| |
| /* |
| 123456789-123456789-123456789-123456789-123456789-123456789-123456789-12 |
| |
| More conventions |
| ================ |
| |
| Argument Checking |
| ----------------- |
| |
| Functions that take objects as arguments normally don't check for nil |
| arguments, but they do check the type of the argument, and return an |
| error if the function doesn't apply to the type. |
| |
| Failure Modes |
| ------------- |
| |
| Functions may fail for a variety of reasons, including running out of |
| memory. This is communicated to the caller in two ways: an error string |
| is set (see errors.h), and the function result differs: functions that |
| normally return a pointer return NULL for failure, functions returning |
| an integer return -1 (which could be a legal return value too!), and |
| other functions return 0 for success and -1 for failure. |
| Callers should always check for errors before using the result. |
| |
| Reference Counts |
| ---------------- |
| |
| It takes a while to get used to the proper usage of reference counts. |
| |
| Functions that create an object set the reference count to 1; such new |
| objects must be stored somewhere or destroyed again with Py_DECREF(). |
| Functions that 'store' objects such as PyTuple_SetItem() and |
| PyDict_SetItemString() |
| don't increment the reference count of the object, since the most |
| frequent use is to store a fresh object. Functions that 'retrieve' |
| objects such as PyTuple_GetItem() and PyDict_GetItemString() also |
| don't increment |
| the reference count, since most frequently the object is only looked at |
| quickly. Thus, to retrieve an object and store it again, the caller |
| must call Py_INCREF() explicitly. |
| |
| NOTE: functions that 'consume' a reference count like |
| PyDict_SetItemString() even |
| consume the reference if the object wasn't stored, to simplify error |
| handling. |
| |
| It seems attractive to make other functions that take an object as |
| argument consume a reference count; however this may quickly get |
| confusing (even the current practice is already confusing). Consider |
| it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at |
| times. |
| |
| 123456789-123456789-123456789-123456789-123456789-123456789-123456789-12 |
| */ |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| #endif /* !Py_OBJECT_H */ |