Get a strong reference to a constant.
Set an exception and return NULL if constant_id is invalid.
constant_id must be one of these constant identifiers:
Constant Identifier |
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Returned object |
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Numeric values are only given for projects which cannot use the constant identifiers.
Added in version 3.13.
CPython implementation detail: In CPython, all of these constants are immortal.
Similar to Py_GetConstant(), but return a borrowed
reference.
This function is primarily intended for backwards compatibility:
using Py_GetConstant() is recommended for new code.
The reference is borrowed from the interpreter, and is valid until the interpreter finalization.
Added in version 3.13.
The NotImplemented singleton, used to signal that an operation is
not implemented for the given type combination.
Properly handle returning Py_NotImplemented from within a C
function (that is, create a new strong reference
to NotImplemented and return it).
Flag to be used with multiple functions that print the object (like
PyObject_Print() and PyFile_WriteObject()).
If passed, these functions use the str() of the object
instead of the repr().
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; if given, the str() of the object is written
instead of the repr().
Returns 1 if o has the attribute attr_name, and 0 otherwise.
This is equivalent to the Python expression hasattr(o, attr_name).
On failure, return -1.
Added in version 3.13.
This is the same as PyObject_HasAttrWithError(), but attr_name is
specified as a const char* UTF-8 encoded bytes string,
rather than a PyObject*.
Added in version 3.13.
Returns 1 if o has the attribute attr_name, and 0 otherwise.
This function always succeeds.
Note
Exceptions that occur when this calls __getattr__() and
__getattribute__() methods aren’t propagated,
but instead given to sys.unraisablehook().
For proper error handling, use PyObject_HasAttrWithError(),
PyObject_GetOptionalAttr() or PyObject_GetAttr() instead.
This is the same as PyObject_HasAttr(), but attr_name is
specified as a const char* UTF-8 encoded bytes string,
rather than a PyObject*.
Note
Exceptions that occur when this calls __getattr__() and
__getattribute__() methods or while creating the temporary
str object are silently ignored.
For proper error handling, use PyObject_HasAttrStringWithError(),
PyObject_GetOptionalAttrString()
or PyObject_GetAttrString() instead.
Retrieve an attribute named attr_name from object o. Returns the attribute
value on success, or NULL on failure. This is the equivalent of the Python
expression o.attr_name.
If the missing attribute should not be treated as a failure, you can use
PyObject_GetOptionalAttr() instead.
This is the same as PyObject_GetAttr(), but attr_name is
specified as a const char* UTF-8 encoded bytes string,
rather than a PyObject*.
If the missing attribute should not be treated as a failure, you can use
PyObject_GetOptionalAttrString() instead.
Variant of PyObject_GetAttr() which doesn’t raise
AttributeError if the attribute is not found.
If the attribute is found, return 1 and set *result to a new
strong reference to the attribute.
If the attribute is not found, return 0 and set *result to NULL;
the AttributeError is silenced.
If an error other than AttributeError is raised, return -1 and
set *result to NULL.
Added in version 3.13.
This is the same as PyObject_GetOptionalAttr(), but attr_name is
specified as a const char* UTF-8 encoded bytes string,
rather than a PyObject*.
Added in version 3.13.
Generic attribute getter function that is meant to be put into a type
object’s tp_getattro slot. It looks for a descriptor in the dictionary
of classes in the object’s MRO as well as an attribute in the object’s
__dict__ (if present). As outlined in Implementing Descriptors,
data descriptors take preference over instance attributes, while non-data
descriptors don’t. Otherwise, an AttributeError is raised.
Set the value of the attribute named attr_name, for object o, to the value
v. Raise an exception and return -1 on failure;
return 0 on success. This is the equivalent of the Python statement
o.attr_name = v.
If v is NULL, the attribute is deleted. This behaviour is deprecated
in favour of using PyObject_DelAttr(), but there are currently no
plans to remove it.
This is the same as PyObject_SetAttr(), but attr_name is
specified as a const char* UTF-8 encoded bytes string,
rather than a PyObject*.
If v is NULL, the attribute is deleted, but this feature is
deprecated in favour of using PyObject_DelAttrString().
The number of different attribute names passed to this function
should be kept small, usually by using a statically allocated string
as attr_name.
For attribute names that aren’t known at compile time, prefer calling
PyUnicode_FromString() and PyObject_SetAttr() directly.
For more details, see PyUnicode_InternFromString(), which may be
used internally to create a key object.
Generic attribute setter and deleter function that is meant
to be put into a type object’s tp_setattro
slot. It looks for a data descriptor in the
dictionary of classes in the object’s MRO, and if found it takes preference
over setting or deleting the attribute in the instance dictionary. Otherwise, the
attribute is set or deleted in the object’s __dict__ (if present).
On success, 0 is returned, otherwise an AttributeError
is raised and -1 is returned.
Delete attribute named attr_name, for object o. Returns -1 on failure.
This is the equivalent of the Python statement del o.attr_name.
This is the same as PyObject_DelAttr(), but attr_name is
specified as a const char* UTF-8 encoded bytes string,
rather than a PyObject*.
The number of different attribute names passed to this function
should be kept small, usually by using a statically allocated string
as attr_name.
For attribute names that aren’t known at compile time, prefer calling
PyUnicode_FromString() and PyObject_DelAttr() directly.
For more details, see PyUnicode_InternFromString(), which may be
used internally to create a key object for lookup.
A generic implementation for the getter of a __dict__ descriptor. It
creates the dictionary if necessary.
This function may also be called to get the __dict__
of the object o. Pass NULL for context when calling it.
Since this function may need to allocate memory for the
dictionary, it may be more efficient to call PyObject_GetAttr()
when accessing an attribute on the object.
On failure, returns NULL with an exception set.
Added in version 3.3.
A generic implementation for the setter of a __dict__ descriptor. This
implementation does not allow the dictionary to be deleted.
Added in version 3.3.
Return a pointer to __dict__ of the object obj.
If there is no __dict__, return NULL without setting an exception.
This function may need to allocate memory for the
dictionary, so it may be more efficient to call PyObject_GetAttr()
when accessing an attribute on the object.
Compare the values of o1 and o2 using the operation specified by opid,
which must be one of Py_LT, Py_LE, Py_EQ,
Py_NE, Py_GT, or Py_GE, corresponding to <,
<=, ==, !=, >, or >= respectively. This is the equivalent of
the Python expression o1 op o2, where op is the operator corresponding
to opid. Returns the value of the comparison on success, or NULL on failure.
Compare the values of o1 and o2 using the operation specified by opid,
like PyObject_RichCompare(), but returns -1 on error, 0 if
the result is false, 1 otherwise.
Note
If o1 and o2 are the same object, PyObject_RichCompareBool()
will always return 1 for Py_EQ and 0 for Py_NE.
Format obj using format_spec. This is equivalent to the Python
expression format(obj, format_spec).
format_spec may be NULL. In this case the call is equivalent
to format(obj).
Returns the formatted string on success, NULL on failure.
Compute a 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.
Changed in version 3.4: This function now includes a debug assertion to help ensure that it does not silently discard an active exception.
As PyObject_Repr(), compute a string representation of object o, but
escape the non-ASCII characters in the string returned by
PyObject_Repr() with \x, \u or \U escapes. This generates
a string similar to that returned by PyObject_Repr() in Python 2.
Called by the ascii() built-in function.
Compute a 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, therefore, by the print() function.
Changed in version 3.4: This function now includes a debug assertion to help ensure that it does not silently discard an active exception.
Compute a bytes representation of object o. NULL is returned on
failure and a bytes object on success. This is equivalent to the Python
expression bytes(o), when o is not an integer. Unlike bytes(o),
a TypeError is raised when o is an integer instead of a zero-initialized
bytes object.
Return 1 if the class derived is identical to or derived from the class
cls, otherwise return 0. In case of an error, return -1.
If cls is a tuple, the check will be done against every entry in cls.
The result will be 1 when at least one of the checks returns 1,
otherwise it will be 0.
If cls has a __subclasscheck__() method, it will be called to
determine the subclass status as described in PEP 3119. Otherwise,
derived is a subclass of cls if it is a direct or indirect subclass,
i.e. contained in cls.__mro__.
Normally only class objects, i.e. instances of type or a derived
class, are considered classes. However, objects can override this by having
a __bases__ attribute (which must be a tuple of base classes).
Return 1 if inst is an instance of the class cls or a subclass of
cls, or 0 if not. On error, returns -1 and sets an exception.
If cls is a tuple, the check will be done against every entry in cls.
The result will be 1 when at least one of the checks returns 1,
otherwise it will be 0.
If cls has a __instancecheck__() method, it will be called to
determine the subclass status as described in PEP 3119. Otherwise, inst
is an instance of cls if its class is a subclass of cls.
An instance inst can override what is considered its class by having a
__class__ attribute.
An object cls can override if it is considered a class, and what its base
classes are, by having a __bases__ attribute (which must be a tuple
of base classes).
Compute and return the hash value of an object o. On failure, return -1.
This is the equivalent of the Python expression hash(o).
Changed in version 3.2: The return type is now Py_hash_t. This is a signed integer the same size
as Py_ssize_t.
Set a TypeError indicating that type(o) is not hashable and return -1.
This function receives special treatment when stored in a tp_hash slot,
allowing a type to explicitly indicate to the interpreter that it is not
hashable.
Returns 1 if the object o is considered to be true, and 0 otherwise.
This is equivalent to the Python expression not not o. On failure, return
-1.
Returns 0 if the object o is considered to be true, and 1 otherwise.
This is equivalent to the Python expression not o. On failure, return
-1.
When o is non-NULL, returns a type object corresponding to the object type
of object o. On failure, raises SystemError and returns NULL. This
is equivalent to the Python expression type(o).
This function creates a new strong reference to the return value.
There’s really no reason to use this
function instead of the Py_TYPE() function, which returns a
pointer of type PyTypeObject*, except when a new
strong reference is needed.
Return non-zero if the object o is of type type or a subtype of type, and
0 otherwise. Both parameters must be non-NULL.
Return the length of object o. If the object o provides either the sequence
and mapping protocols, the sequence length is returned. On error, -1 is
returned. This is the equivalent to the Python expression len(o).
Return an estimated length for the object o. First try to return its
actual length, then an estimate using __length_hint__(), and
finally return the default value. On error return -1. This is the
equivalent to the Python expression operator.length_hint(o, defaultvalue).
Added in version 3.4.
Return element of o corresponding to the object key or NULL on failure.
This is the equivalent of the Python expression o[key].
Map the object key to the value v. Raise an exception and
return -1 on failure; return 0 on success. This is the
equivalent of the Python statement o[key] = v. This function does
not steal a reference to v.
Remove the mapping for the object key from the object o. Return -1
on failure. This is equivalent to the Python statement del o[key].
This is the same as PyObject_DelItem(), but key is
specified as a const char* UTF-8 encoded bytes string,
rather than a PyObject*.
This is equivalent to the Python expression dir(o), returning a (possibly
empty) list of strings appropriate for the object argument, or NULL if there
was an error. If the argument is NULL, this is like the Python dir(),
returning the names of the current locals; in this case, if no execution frame
is active then NULL is returned but PyErr_Occurred() will return false.
This is equivalent to the Python expression iter(o). It returns a new
iterator for the object argument, or the object itself if the object is already
an iterator. Raises TypeError and returns NULL if the object cannot be
iterated.
This is equivalent to the Python __iter__(self): return self method.
It is intended for iterator types, to be used in the PyTypeObject.tp_iter slot.
This is the equivalent to the Python expression aiter(o). Takes an
AsyncIterable object and returns an AsyncIterator for it.
This is typically a new iterator but if the argument is an
AsyncIterator, this returns itself. Raises TypeError and
returns NULL if the object cannot be iterated.
Added in version 3.10.
Get a pointer to subclass-specific data reserved for cls.
The object o must be an instance of cls, and cls must have been
created using negative PyType_Spec.basicsize.
Python does not check this.
On error, set an exception and return NULL.
Added in version 3.12.
Return the size of the instance memory space reserved for cls, i.e. the size of the
memory PyObject_GetTypeData() returns.
This may be larger than requested using -PyType_Spec.basicsize;
it is safe to use this larger size (e.g. with memset()).
The type cls must have been created using
negative PyType_Spec.basicsize.
Python does not check this.
On error, set an exception and return a negative value.
Added in version 3.12.
Get a pointer to per-item data for a class with
Py_TPFLAGS_ITEMS_AT_END.
On error, set an exception and return NULL.
TypeError is raised if o does not have
Py_TPFLAGS_ITEMS_AT_END set.
Added in version 3.12.
Visit the managed dictionary of obj.
This function must only be called in a traverse function of the type which
has the Py_TPFLAGS_MANAGED_DICT flag set.
Added in version 3.13.
Clear the managed dictionary of obj.
This function must only be called in a clear function of the type which
has the Py_TPFLAGS_MANAGED_DICT flag set.
Added in version 3.13.
Enable deferred reference counting on obj, if supported by the runtime. In the free-threaded build, this allows the interpreter to avoid reference count adjustments to obj, which may improve multi-threaded performance. The tradeoff is that obj will only be deallocated by the tracing garbage collector, and not when the interpreter no longer has any references to it.
This function returns 1 if deferred reference counting is enabled on obj,
and 0 if deferred reference counting is not supported or if the hint was
ignored by the interpreter, such as when deferred reference counting is already
enabled on obj. This function is thread-safe, and cannot fail.
This function does nothing on builds with the GIL enabled, which do
not support deferred reference counting. This also does nothing if obj is not
an object tracked by the garbage collector (see gc.is_tracked() and
PyObject_GC_IsTracked()).
This function is intended to be used soon after obj is created,
by the code that creates it, such as in the object’s tp_new
slot.
Added in version 3.14.
Check if obj is a unique temporary object.
Returns 1 if obj is known to be a unique temporary object,
and 0 otherwise. This function cannot fail, but the check is
conservative, and may return 0 in some cases even if obj is a unique
temporary object.
If an object is a unique temporary, it is guaranteed that the current code
has the only reference to the object. For arguments to C functions, this
should be used instead of checking if the reference count is 1. Starting
with Python 3.14, the interpreter internally avoids some reference count
modifications when loading objects onto the operands stack by
borrowing references when possible, which means
that a reference count of 1 by itself does not guarantee that a function
argument uniquely referenced.
In the example below, my_func is called with a unique temporary object
as its argument:
my_func([1, 2, 3])
In the example below, my_func is not called with a unique temporary
object as its argument, even if its refcount is 1:
my_list = [1, 2, 3]
my_func(my_list)
See also the function Py_REFCNT().
Added in version 3.14.
This function returns non-zero if obj is immortal, and zero otherwise. This function cannot fail.
Note
Objects that are immortal in one CPython version are not guaranteed to be immortal in another.
Added in version 3.14.
Increments the reference count of obj if it is not zero. Returns 1
if the object’s reference count was successfully incremented. Otherwise,
this function returns 0.
PyUnstable_EnableTryIncRef() must have been called
earlier on obj or this function may spuriously return 0 in the
free threading build.
This function is logically equivalent to the following C code, except that it behaves atomically in the free threading build:
if (Py_REFCNT(op) > 0) {
Py_INCREF(op);
return 1;
}
return 0;
This is intended as a building block for managing weak references without the overhead of a Python weak reference object.
Typically, correct use of this function requires support from obj’s
deallocator (tp_dealloc).
For example, the following sketch could be adapted to implement a
“weakmap” that works like a WeakValueDictionary
for a specific type:
PyMutex mutex;
PyObject *
add_entry(weakmap_key_type *key, PyObject *value)
{
PyUnstable_EnableTryIncRef(value);
weakmap_type weakmap = ...;
PyMutex_Lock(&mutex);
weakmap_add_entry(weakmap, key, value);
PyMutex_Unlock(&mutex);
Py_RETURN_NONE;
}
PyObject *
get_value(weakmap_key_type *key)
{
weakmap_type weakmap = ...;
PyMutex_Lock(&mutex);
PyObject *result = weakmap_find(weakmap, key);
if (PyUnstable_TryIncRef(result)) {
// `result` is safe to use
PyMutex_Unlock(&mutex);
return result;
}
// if we get here, `result` is starting to be garbage-collected,
// but has not been removed from the weakmap yet
PyMutex_Unlock(&mutex);
return NULL;
}
// tp_dealloc function for weakmap values
void
value_dealloc(PyObject *value)
{
weakmap_type weakmap = ...;
PyMutex_Lock(&mutex);
weakmap_remove_value(weakmap, value);
...
PyMutex_Unlock(&mutex);
}
Added in version 3.14.
Enables subsequent uses of PyUnstable_TryIncRef() on obj. The
caller must hold a strong reference to obj when calling this.
Added in version 3.14.
Determine if op only has one reference.
On GIL-enabled builds, this function is equivalent to Py_REFCNT(op) == 1.
On a free threaded build, this checks if op’s reference count is equal to one and additionally checks if op is only used by this thread. Py_REFCNT(op) == 1 is not thread-safe on free threaded builds; prefer this function.
The caller must hold an attached thread state, despite the fact that this function doesn’t call into the Python interpreter. This function cannot fail.
Added in version 3.14.