Revision 15 as of 2006-11-29 16:31:27

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Possible Python 3K Class Tree?

This page contain an incomplete thinking-out-loud description of a re-factoring of the base and built-in Python types into a set of Abstract Base Classes (ABCs) and concrete types. This would probably be a good time to enumerate the exceptions various basic operations can raise, as well.

Some questions:

Do you mean optional methods (a deque may not be appropriate for sorting)? Or are you talking about parameters on methods (such as the "key" keyword of most sort methods)?

I'm assuming that True and False will still exist, and this question is really about the bool special method (replacing today's nonzero), that is used when an arbitrary object is tested for true/false.

Comparable:
 equals (Comparable) => Boolean

Object (Comparable):
 hash () => Integer
 # presumable for "is" we compare the ids of the two objects
 id () => Integer
 true () => Boolean
 # the __str__ method
 printable () => String
 class () => Type
 implements (Type) => Boolean

Type (Object):
 name () => String
 # supertypes yields list of immediate parent types (what's in __bases__)
 supertypes () => Sequence
 # interfaces yields flattened list of all interface types this implements
 interfaces () => Sequence

Ellipsis (Object):
 # contains only the single value represented by three dots
 ThreeDots

Null (Object):
 # only a single value of this type
 None

Exception (Object):
 args () => Sequence

ExceptionContext (Object):
 exception () => Exception
 traceback () => Traceback

Boolean (Object):
 True
 False

Orderable:
 less_than (Object) => Boolean
 greater_than (Object) => Boolean

Numeric:
 add (Numeric) => Numeric
 subtract (Numeric) => Numeric
 product (Numeric) => Numeric
 quotient (Numeric) => Numeric
 floored_quotient (Numeric) => Numeric
 remainder (Numeric) => Numeric
 negate (Numeric) => Numeric
 absolute_value () => Numeric
 exponentiate (Numeric) => Numeric
 magnitude () => Numeric

Integer (Object, Orderable, Numeric):
 or (Integer) => Integer
 xor (Integer) => Integer
 and (Integer) => Integer
 shift (Integer) => Integer
 invert (Integer) => Integer
 real () => Real

Real (Object, Orderable, Numeric):
 floor () => Integer
 ceiling () => Integer

Complex (Object, Orderable, Numeric):
 conjugate () => Complex

Decimal (Object, Orderable, Numeric):
 TBD

Iterable:
 iterator () => Iteration

Iteration (Object, Iterable):
 next () => other

KeyValueIterable (Iterable):
 # yields iteration of key-value pairs 

# should Container be Iterable, or should that be reserved for real types, like Tuple?
Container (Iterable):
 len () => Integer
 contains (Object) => Boolean

Set (Container):
 is_subset (Set) => Boolean
 is_superset (Set) => Boolean
 union_with (Set) => Set
 intersection_with (Set) => Set
 difference (Set) => Set
 symmetric_difference (Set) => Set
 # should this be "multiply" to match Sequence?
 shallow_copy () => Set

Sequence (Container):
 contains (Sequence) => Sequence
 # normal access via index
 slice1 (Integer) => Object
 # normal slice of range
 slice2 (Integer, Integer) => Sequence
 # slice with step K
 slice3 (Integer, Integer, Integer) => Sequence
 # return self + other Sequence
 concatenate (Sequence) => Sequence
 # N shallow copies of self
 multiply (Integer) => Sequence
 # do "min" and "max" make sense over arbitrary sequences?  Should really only apply to sequences of "Orderable"
 min () => Object
 max () => Object

MutableSequence (Sequence):
 append (Object) => self
 insert (Integer position, Object) => self
 # value at I is replaced with Object
 replace (Integer position, Object) => self
 # slice from I to J is replaced with values of Iterator
 replace2 (Integer start, Integer end, Iterable) => self
 # slice from I to J with step K is replaced by Iterator
 replace3 (Integer start, Integer end, Integer step, Iterable) => self
 extend (Object) => self
 count (Object) => Integer
 reverse ()
 index1 (Object) => Integer
 index2 (Object, Integer start, Integer end) => Object
 pop1 () => Object
 pop2 (Integer position) => Object
 delete1 (Integer position) => self
 delete2 (Integer start, Integer end) => self
 delete3 (Integer start, Integer end, Integer step) => self
 sort0 () => self
 sort1 (Function comparison_fn) => self
 sort2 (Function comparison_fn, Function key_fn) => self
 sort3 (Function comparison_fn, Function key_fn, Boolean reverse) => self

ByteSequence (Object, Sequence):
 # should this be a MutableSequence?

Buffer (Object, MutableSequence):
 # is this just mutable version of ByteSequence?

String (Object, Sequence):
 TBD

Tuple (Object, Sequence):

List (Object, MutableSequence):

Mapping:
 get (Object key) => Object
 get_with_default (Object key, Object default) => Object
 set (Object key, Object value)
 # should delete return the deleted value?  Why not.  That removes the need for "pop".
 delete (Object key) => Object
 clear ()
 copy () => Mapping
 contains (Object key) => Boolean
 # items returns a value which is guaranteed to satisfy both the Set interface and the KeyValueIterable interface
 items () => (Set and KeyValueIterable)
 keys () => Set
 values () => Set
 # get_or_set is the current "setdefault"
 get_or_set (Object key, Object value) => Object
 update (Mapping) => self
 # alternate form of "update" takes Iterable of key-value pairs
 update (KeyValueIterable) => self
 # do we really need fromkeys?
 fromkeys (Sequence keys, Object initial_value) => Mapping

Dict (Object, Mapping, Container):
 # should some methods (e.g., "fromkeys") be here instead of in Mapping?

ExecutionContext:
 enter () => ExecutionContext
 exit (ExceptionContext) => Boolean

Stream:
 close ()
 flush ()
 read () => ByteSequence
 read (Integer) => ByteSequence
 write (ByteSequence) => Integer

RandomAccessStream (Stream):
 # do we really need to continue to mimic the low-level UNIX seek and tell?
 # why not use Python sequence-style indices for offset?
 seek (Integer offset)
 tell () => Integer

TextStream (Stream):
 readline () => String
 readlines () => Sequence
 writeline (String) => Boolean
 writelines (Sequence) => Boolean
 encoding () => String

OpenFile (RandomAccessStream):
 # it would be great if this had a "mimetype" method
 fileno () => Integer
 filename () => String
 isatty () => Boolean
 truncate (Integer size)
 mode () => String
 
BinaryOpenFile (Object, Stream, OpenFile, Iterable, ExecutionContext):

TextOpenFile (Object, TextStream, OpenFile, Iterable, ExecutionContext):


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