Notice: While JavaScript is not essential for this website, your interaction with the content will be limited. Please turn JavaScript on for the full experience.
...dict_get_version(dict) and dict_get_entry_version(dict) functions: UNSET = object() class GuardDictKey: def __init__(self, dict, key): self.dict = dict self.key = key self.dict_version = dict_get_version(dict) self.entry_version = dict_get_entry_version(dict, key) def check(self): """Return True if the dictionary entry did not change and the dictionary was not replaced.""" # read the version of the dictionary dict_versio...
...Dict joining using + and += PEP: Dict addition and subtraction PEP 584: Add + and += operators to the built-in dict class. Moving PEP 584 forward (dict + and += operators) PEP 584: Add Union Operators To dict Accepting PEP 584: Add Union Operators To dict Ticket on the bug tracker Merging two dictionaries in an expression is a frequently requested feature. For example: https://stackoverflow.com/questions/38987/how-to-merge-two-dictionaries-in-a-single-expression https://stackoverflow.com/quest...
...dict a dict subclass? Why? Yes. Like defaultdict, an ordered dictionary `` subclasses dict. Being a dict subclass make some of the methods faster (like __getitem__ and __len__). More importantly, being a dict subclass lets ordered dictionaries be usable with tools like json that insist on having dict inputs by testing isinstance(d, dict). Do any limitations arise from subclassing dict? Yes. Since the API for dicts is different in Py2.x and Py3.x, the OrderedDict API must also be different....
...dict.keys(), .values() and .items() PEP:3106 Title:Revamping dict.keys(), .values() and .items() Author:Guido van Rossum Status:Final Type:Standards Track Created:19-Dec-2006 Post-History: Contents Abstract Introduction Specification Open Issues References Abstract This PEP proposes to change the .keys(), .values() and .items() methods of the built-in dict type to return a set-like or unordered container object whose contents are derived from the underlying dictionary rather...
...dict-based dispatch is the one true implementation for switch statements and that we should face the limitations up front, so that we can reap maximal benefits. I'm leaning towards school IIb -- duplicate cases should be resolved by the ordering of the cases instead of flagged as errors. When to Freeze the Dispatch Dict For the supporters of school II (dict-based dispatch), the next big dividing issue is when to create the dict used for switching. I call this "freezing the dict". The main pr...
...dictionary comprehension" or "dict comprehension" for short. You can use dict comprehensions in ways very similar to list comprehensions, except that they produce Python dictionary objects instead of list objects. Resolution This PEP was originally written for inclusion in Python 2.3. It was withdrawn after observation that substantially all of its benefits were subsumed by generator expressions coupled with the dict() constructor. However, Python 2.7 and 3.0 introduces this exact feature, a...
...Dict type: webmail.utils.ImmutableDict. It is hashable if keys and values are hashable. It is not truly read-only: its internal dict is a public attribute. remember project: remember.dicts.FrozenDict. It is used to implement a cache: FrozenDict is used to store function callbacks. FrozenDict may be hashable. It has an extra supply_dict() class method to create a FrozenDict from a dict without copying the dict: store the dict as the internal dict. Implementation issue: __init__() can be called to...
...dict a lot). Also, for the wrapper case the interpreter would have to be careful to preserve __order__. KWArgsDict.__order__ This is the same as the dict.__order__ idea, but kwargs would be an instance of a new minimal dict subclass that provides the __order__ attribute. dict would instead be unchanged. Prognosis: Simply switching to OrderedDict is a less complicated and more intuitive change. Acknowledgements Thanks to Andrew Barnert for helpful feedback and to the participants of all th...
...dictionary is replaced by the dictionary returned from __prepare__. This dictionary object can be a regular dictionary or a custom mapping type. This dictionary-like object is not required to support the full dictionary interface. A dictionary which supports a limited set of dictionary operations will restrict what kinds of actions can occur during evaluation of the class body. A minimal implementation might only support adding and retrieving values from the dictionary - most class bodies will d...
...dictionary (or constant tuple). Bytecode Comparison The bytecode generated for annotations functions with this PEP uses the efficient BUILD_CONST_KEY_MAP opcode to build the dict for all annotatable objects: functions, classes, and modules. Stock semantics also uses BUILD_CONST_KEY_MAP bytecode for function annotations. PEP 563 has an even more efficient method for building annotations dicts on functions, leveraging the fact that its annotations dicts only contain strings for both keys and val...
...dict changes to: class celldict(object): def __init__(self, builtindict=()): self.basedict = builtindict self.__dict = d = {} for k, v in builtindict.items(): d[k] = cell(v, 1) def __getitem__(self, key): c = self.__dict.get(key) if c is None or c.objptr is NULL or c.builtinflag: raise KeyError, key return c.objptr def __setitem__(self, key, value): c = self.__dict.get(key) if c is None: ...
...dict): fget = block_dict.pop('fget', None) fset = block_dict.pop('fset', None) fdel = block_dict.pop('fdel', None) doc = block_dict.pop('__doc__', None) assert not block_dict return property(fget, fset, fdel, doc) Example: interfaces Guido [6] and others have occasionally suggested introducing interfaces into python. Most suggestions have offered syntax along the lines of: interface IFoo: """Foo blah blah""" def fumble(name, count): """docstring""" ...
...dictionary used for configuration, and which has a configure() method. A callable, called dictConfigClass, which will (by default) be set to DictConfigurator. This is provided so that if desired, DictConfigurator can be replaced with a suitable user-defined implementation. The dictConfig() function will call dictConfigClass passing the specified dictionary, and then call the configure() method on the returned object to actually put the configuration into effect: def dictConfig(config): di...
...Dict requires passing the key transformation function as the first argument (much like creating a defaultdict requires passing the factory function as first argument). The constructor also takes other optional arguments which can be used to initialize the TransformDict with certain key-value pairs. Those optional arguments are the same as in the dict and defaultdict constructors: >>> d = TransformDict(str.casefold, [('Foo', 1)], Bar=2) >>> sorted(d.items()) [('Bar', 2), ('Foo...
...dict(dict): def __hash__(self): return id(self) def _immutable(self, *args, **kws): raise TypeError('object is immutable') __setitem__ = _immutable __delitem__ = _immutable clear = _immutable update = _immutable setdefault = _immutable pop = _immutable popitem = _immutable class xdict(dict): def __freeze__(self): return imdict(self) >>> s = set([1, 2, 3]) >>> {s: 4} Traceback (most recen...
...dict: ... which is equivalent to, but much faster than for k in dict.keys(): ... as long as the restriction on modifications to the dictionary (either by the loop or by another thread) are not violated. Add methods to dictionaries that return different kinds of iterators explicitly: for key in dict.iterkeys(): ... for value in dict.itervalues(): ... for key, value in dict.iteritems(): ... This means that for x in dict is shorthand for for x in dict.iterkeys(). Other mappings, if they s...
...dict builtin and the mapping API in general to replace the separate list based and iterator based APIs in Python 2 with a merged, memory efficient set and multiset view based API. This new style of dict iteration was also added to the Python 2.7 dict type as a new set of iteration methods. This means that there are now 3 different kinds of dict iteration that may need to be migrated to Python 3 when an application makes the transition: Lists as mutable snapshots: d.items() -> list(d.items())...
...dict The symbolToStringMap() function will accept a DFA instance and return a dictionary object that maps from the DFA's numeric values for its nonterminals to the string names of the nonterminals as found in the original grammar specification for the DFA. stringToSymbolMap (dfa) -> dict The stringToSymbolMap() function output a dictionary mapping the nonterminal names of the input DFA to their corresponding numeric values. Extra credit will be awarded if the map generation functions and pa...
...dict" test as well as the new "for key in dict:" to iterate efficiently (without making a copy of the list of keys) over all keys in a dictionary. It doesn't require the other argument to be a defaultdict or even a dictionary: any mapping object that supports "for key in other" and other[key] will do. Here's the new type at work: >>> print defaultdict # show our type <class '__main__.defaultdict'> >>> print type(defaultdict) # its metatype ...