Dictionary Objects¶

typePyDictObject¶

This subtype ofPyObject represents a Python dictionary object.

PyTypeObjectPyDict_Type¶

Part of theStable ABI.

This instance ofPyTypeObject represents the Python dictionarytype. This is the same object asdict in the Python layer.

intPyDict_Check(PyObject*p)¶

Return true ifp is a dict object or an instance of a subtype of the dicttype. This function always succeeds.

intPyDict_CheckExact(PyObject*p)¶

Return true ifp is a dict object, but not an instance of a subtype ofthe dict type. This function always succeeds.

PyObject*PyDict_New()¶

Return value: New reference. Part of theStable ABI.

Return a new empty dictionary, orNULL on failure.

PyObject*PyDictProxy_New(PyObject*mapping)¶

Return value: New reference. Part of theStable ABI.

Return atypes.MappingProxyType object for a mapping whichenforces read-only behavior. This is normally used to create a view toprevent modification of the dictionary for non-dynamic class types.

voidPyDict_Clear(PyObject*p)¶

Part of theStable ABI.

Empty an existing dictionary of all key-value pairs.

intPyDict_Contains(PyObject*p,PyObject*key)¶

Part of theStable ABI.

Determine if dictionaryp containskey. If an item inp is matcheskey, return1, otherwise return0. On error, return-1.This is equivalent to the Python expressionkeyinp.

intPyDict_ContainsString(PyObject*p,constchar*key)¶

This is the same asPyDict_Contains(), butkey is specified as aconstchar* UTF-8 encoded bytes string, rather than aPyObject*.

Added in version 3.13.

PyObject*PyDict_Copy(PyObject*p)¶

Return value: New reference. Part of theStable ABI.

Return a new dictionary that contains the same key-value pairs asp.

intPyDict_SetItem(PyObject*p,PyObject*key,PyObject*val)¶

Part of theStable ABI.

Insertval into the dictionaryp with a key ofkey.key must behashable; if it isn’t,TypeError will be raised. Return0 on success or-1 on failure. This functiondoes not steal areference toval.

intPyDict_SetItemString(PyObject*p,constchar*key,PyObject*val)¶

Part of theStable ABI.

This is the same asPyDict_SetItem(), butkey isspecified as aconstchar* UTF-8 encoded bytes string,rather than aPyObject*.

intPyDict_DelItem(PyObject*p,PyObject*key)¶

Part of theStable ABI.

Remove the entry in dictionaryp with keykey.key must behashable;if it isn’t,TypeError is raised.Ifkey is not in the dictionary,KeyError is raised.Return0 on success or-1 on failure.

intPyDict_DelItemString(PyObject*p,constchar*key)¶

Part of theStable ABI.

This is the same asPyDict_DelItem(), butkey isspecified as aconstchar* UTF-8 encoded bytes string,rather than aPyObject*.

intPyDict_GetItemRef(PyObject*p,PyObject*key,PyObject**result)¶

Part of theStable ABI since version 3.13.

Return a newstrong reference to the object from dictionarypwhich has a keykey:

• If the key is present, set*result to a newstrong referenceto the value and return1.

• If the key is missing, set*result toNULL and return0.

• On error, raise an exception and return-1.

Added in version 3.13.

See also thePyObject_GetItem() function.

PyObject*PyDict_GetItem(PyObject*p,PyObject*key)¶

Return value: Borrowed reference. Part of theStable ABI.

Return aborrowed reference to the object from dictionaryp whichhas a keykey. ReturnNULL if the keykey is missingwithoutsetting an exception.

Note

Exceptions that occur while this calls__hash__() and__eq__() methods are silently ignored.Prefer thePyDict_GetItemWithError() function instead.

Changed in version 3.10:Calling this API withoutGIL held had been allowed for historicalreason. It is no longer allowed.

PyObject*PyDict_GetItemWithError(PyObject*p,PyObject*key)¶

Return value: Borrowed reference. Part of theStable ABI.

Variant ofPyDict_GetItem() that does not suppressexceptions. ReturnNULLwith an exception set if an exceptionoccurred. ReturnNULLwithout an exception set if the keywasn’t present.

PyObject*PyDict_GetItemString(PyObject*p,constchar*key)¶

Return value: Borrowed reference. Part of theStable ABI.

This is the same asPyDict_GetItem(), butkey is specified as aconstchar* UTF-8 encoded bytes string, rather than aPyObject*.

Note

Exceptions that occur while this calls__hash__() and__eq__() methods or while creating the temporarystrobject are silently ignored.Prefer using thePyDict_GetItemWithError() function with your ownPyUnicode_FromString()key instead.

intPyDict_GetItemStringRef(PyObject*p,constchar*key,PyObject**result)¶

Part of theStable ABI since version 3.13.

Similar toPyDict_GetItemRef(), butkey is specified as aconstchar* UTF-8 encoded bytes string, rather than aPyObject*.

Added in version 3.13.

PyObject*PyDict_SetDefault(PyObject*p,PyObject*key,PyObject*defaultobj)¶

Return value: Borrowed reference.

This is the same as the Python-leveldict.setdefault(). If present, itreturns the value corresponding tokey from the dictionaryp. If the keyis not in the dict, it is inserted with valuedefaultobj anddefaultobjis returned. This function evaluates the hash function ofkey only once,instead of evaluating it independently for the lookup and the insertion.

Added in version 3.4.

intPyDict_SetDefaultRef(PyObject*p,PyObject*key,PyObject*default_value,PyObject**result)¶

Insertsdefault_value into the dictionaryp with a key ofkey if thekey is not already present in the dictionary. Ifresult is notNULL,then*result is set to astrong reference to eitherdefault_value, if the key was not present, or the existing value, ifkeywas already present in the dictionary.Returns1 if the key was present anddefault_value was not inserted,or0 if the key was not present anddefault_value was inserted.On failure, returns-1, sets an exception, and sets*resulttoNULL.

For clarity: if you have a strong reference todefault_value beforecalling this function, then after it returns, you hold a strong referenceto bothdefault_value and*result (if it’s notNULL).These may refer to the same object: in that case you hold two separatereferences to it.

Added in version 3.13.

intPyDict_Pop(PyObject*p,PyObject*key,PyObject**result)¶

Removekey from dictionaryp and optionally return the removed value.Do not raiseKeyError if the key missing.

• If the key is present, set*result to a new reference to the removedvalue ifresult is notNULL, and return1.

• If the key is missing, set*result toNULL ifresult is notNULL, and return0.

• On error, raise an exception and return-1.

Similar todict.pop(), but without the default value andnot raisingKeyError if the key missing.

Added in version 3.13.

intPyDict_PopString(PyObject*p,constchar*key,PyObject**result)¶

Similar toPyDict_Pop(), butkey is specified as aconstchar* UTF-8 encoded bytes string, rather than aPyObject*.

Added in version 3.13.

PyObject*PyDict_Items(PyObject*p)¶

Return value: New reference. Part of theStable ABI.

Return aPyListObject containing all the items from the dictionary.

PyObject*PyDict_Keys(PyObject*p)¶

Return value: New reference. Part of theStable ABI.

Return aPyListObject containing all the keys from the dictionary.

PyObject*PyDict_Values(PyObject*p)¶

Return value: New reference. Part of theStable ABI.

Return aPyListObject containing all the values from the dictionaryp.

Py_ssize_tPyDict_Size(PyObject*p)¶

Part of theStable ABI.

Return the number of items in the dictionary. This is equivalent tolen(p) on a dictionary.

intPyDict_Next(PyObject*p,Py_ssize_t*ppos,PyObject**pkey,PyObject**pvalue)¶

Part of theStable ABI.

Iterate over all key-value pairs in the dictionaryp. ThePy_ssize_t referred to byppos must be initialized to0prior to the first call to this function to start the iteration; thefunction returns true for each pair in the dictionary, and false once allpairs have been reported. The parameterspkey andpvalue should eitherpoint toPyObject* variables that will be filled in with each keyand value, respectively, or may beNULL. Any references returned throughthem are borrowed.ppos should not be altered during iteration. Itsvalue represents offsets within the internal dictionary structure, andsince the structure is sparse, the offsets are not consecutive.

For example:

PyObject*key,*value;Py_ssize_tpos=0;while(PyDict_Next(self->dict,&pos,&key,&value)){/* do something interesting with the values... */...}

The dictionaryp should not be mutated during iteration. It is safe tomodify the values of the keys as you iterate over the dictionary, but onlyso long as the set of keys does not change. For example:

PyObject*key,*value;Py_ssize_tpos=0;while(PyDict_Next(self->dict,&pos,&key,&value)){longi=PyLong_AsLong(value);if(i==-1&&PyErr_Occurred()){return-1;}PyObject*o=PyLong_FromLong(i+1);if(o==NULL)return-1;if(PyDict_SetItem(self->dict,key,o)<0){Py_DECREF(o);return-1;}Py_DECREF(o);}

The function is not thread-safe in thefree-threadedbuild without external synchronization. You can usePy_BEGIN_CRITICAL_SECTION to lock the dictionary while iteratingover it:

Py_BEGIN_CRITICAL_SECTION(self->dict);while(PyDict_Next(self->dict,&pos,&key,&value)){...}Py_END_CRITICAL_SECTION();

intPyDict_Merge(PyObject*a,PyObject*b,intoverride)¶

Part of theStable ABI.

Iterate over mapping objectb adding key-value pairs to dictionarya.b may be a dictionary, or any object supportingPyMapping_Keys()andPyObject_GetItem(). Ifoverride is true, existing pairs inawill be replaced if a matching key is found inb, otherwise pairs willonly be added if there is not a matching key ina. Return0 onsuccess or-1 if an exception was raised.

intPyDict_Update(PyObject*a,PyObject*b)¶

Part of theStable ABI.

This is the same asPyDict_Merge(a,b,1) in C, and is similar toa.update(b) in Python except thatPyDict_Update() doesn’t fallback to the iterating over a sequence of key value pairs if the secondargument has no “keys” attribute. Return0 on success or-1 if anexception was raised.

intPyDict_MergeFromSeq2(PyObject*a,PyObject*seq2,intoverride)¶

Part of theStable ABI.

Update or merge into dictionarya, from the key-value pairs inseq2.seq2 must be an iterable object producing iterable objects of length 2,viewed as key-value pairs. In case of duplicate keys, the last wins ifoverride is true, else the first wins. Return0 on success or-1if an exception was raised. Equivalent Python (except for the returnvalue):

defPyDict_MergeFromSeq2(a,seq2,override):forkey,valueinseq2:ifoverrideorkeynotina:a[key]=value

intPyDict_AddWatcher(PyDict_WatchCallbackcallback)¶

Registercallback as a dictionary watcher. Return a non-negative integerid which must be passed to future calls toPyDict_Watch(). In caseof error (e.g. no more watcher IDs available), return-1 and set anexception.

Added in version 3.12.

intPyDict_ClearWatcher(intwatcher_id)¶

Clear watcher identified bywatcher_id previously returned fromPyDict_AddWatcher(). Return0 on success,-1 on error (e.g.if the givenwatcher_id was never registered.)

Added in version 3.12.

intPyDict_Watch(intwatcher_id,PyObject*dict)¶

Mark dictionarydict as watched. The callback grantedwatcher_id byPyDict_AddWatcher() will be called whendict is modified ordeallocated. Return0 on success or-1 on error.

Added in version 3.12.

intPyDict_Unwatch(intwatcher_id,PyObject*dict)¶

Mark dictionarydict as no longer watched. The callback grantedwatcher_id byPyDict_AddWatcher() will no longer be called whendict is modified or deallocated. The dict must previously have beenwatched by this watcher. Return0 on success or-1 on error.

Added in version 3.12.

typePyDict_WatchEvent¶

Enumeration of possible dictionary watcher events:PyDict_EVENT_ADDED,PyDict_EVENT_MODIFIED,PyDict_EVENT_DELETED,PyDict_EVENT_CLONED,PyDict_EVENT_CLEARED, orPyDict_EVENT_DEALLOCATED.

Added in version 3.12.

typedefint(*PyDict_WatchCallback)(PyDict_WatchEventevent,PyObject*dict,PyObject*key,PyObject*new_value)¶

Type of a dict watcher callback function.

Ifevent isPyDict_EVENT_CLEARED orPyDict_EVENT_DEALLOCATED, bothkey andnew_value will beNULL. Ifevent isPyDict_EVENT_ADDEDorPyDict_EVENT_MODIFIED,new_value will be the new value forkey.Ifevent isPyDict_EVENT_DELETED,key is being deleted from thedictionary andnew_value will beNULL.

PyDict_EVENT_CLONED occurs whendict was previously empty and anotherdict is merged into it. To maintain efficiency of this operation, per-keyPyDict_EVENT_ADDED events are not issued in this case; instead asinglePyDict_EVENT_CLONED is issued, andkey will be the sourcedictionary.

The callback may inspect but must not modifydict; doing so could haveunpredictable effects, including infinite recursion. Do not trigger Pythoncode execution in the callback, as it could modify the dict as a side effect.

Ifevent isPyDict_EVENT_DEALLOCATED, taking a new reference in thecallback to the about-to-be-destroyed dictionary will resurrect it andprevent it from being freed at this time. When the resurrected object isdestroyed later, any watcher callbacks active at that time will be calledagain.

Callbacks occur before the notified modification todict takes place, sothe prior state ofdict can be inspected.

If the callback sets an exception, it must return-1; this exception willbe printed as an unraisable exception usingPyErr_WriteUnraisable().Otherwise it should return0.

There may already be a pending exception set on entry to the callback. Inthis case, the callback should return0 with the same exception stillset. This means the callback may not call any other API that can set anexception unless it saves and clears the exception state first, and restoresit before returning.

Added in version 3.12.