enable more robust multiple dispatch with plum

fastcore/_nbdev.py

@@ -227,10 +227,8 @@
          "do_request": "03b_net.ipynb",
          "start_server": "03b_net.ipynb",
          "start_client": "03b_net.ipynb",
-         "lenient_issubclass": "04_dispatch.ipynb",
-         "sorted_topologically": "04_dispatch.ipynb",
-         "TypeDispatch": "04_dispatch.ipynb",
-         "DispatchReg": "04_dispatch.ipynb",
+         "FastFunction": "04_dispatch.ipynb",
+         "FastDispatcher": "04_dispatch.ipynb",
          "typedispatch": "04_dispatch.ipynb",
          "retain_meta": "04_dispatch.ipynb",
          "default_set_meta": "04_dispatch.ipynb",

fastcore/basics.py

@@ -888,6 +888,8 @@ def copy_func(f):
     fn = FunctionType(f.__code__, f.__globals__, f.__name__, f.__defaults__, f.__closure__)
     fn.__kwdefaults__ = f.__kwdefaults__
     fn.__dict__.update(f.__dict__)
+    fn.__annotations__.update(f.__annotations__)
+    fn.__qualname__ = f.__qualname__
     return fn
 
 # Cell

fastcore/dispatch.py

@@ -4,154 +4,96 @@
 from __future__ import annotations
 
 
-__all__ = ['lenient_issubclass', 'sorted_topologically', 'TypeDispatch', 'DispatchReg', 'typedispatch', 'cast',
-           'retain_meta', 'default_set_meta', 'retain_type', 'retain_types', 'explode_types']
+__all__ = ['FastFunction', 'FastDispatcher', 'typedispatch', 'cast', 'retain_meta', 'default_set_meta', 'retain_type',
+           'retain_types', 'explode_types']
 
 # Cell
 #nbdev_comment from __future__ import annotations
 from .imports import *
 from .foundation import *
 from .utils import *
+from .meta import delegates
 
 from collections import defaultdict
+from plum import Function, Dispatcher
 
 # Cell
-def lenient_issubclass(cls, types):
-    "If possible return whether `cls` is a subclass of `types`, otherwise return False."
-    if cls is object and types is not object: return False # treat `object` as highest level
-    try: return isinstance(cls, types) or issubclass(cls, types)
-    except: return False
+def _eval_annotations(f):
+    "Evaluate future annotations before passing to plum to support backported union operator `|`"
+    f = copy_func(f)
+    for k, v in type_hints(f).items(): f.__annotations__[k] = Union[v] if isinstance(v, tuple) else v
+    return f
 
 # Cell
-def sorted_topologically(iterable, *, cmp=operator.lt, reverse=False):
-    "Return a new list containing all items from the iterable sorted topologically"
-    l,res = L(list(iterable)),[]
-    for _ in range(len(l)):
-        t = l.reduce(lambda x,y: y if cmp(y,x) else x)
-        res.append(t), l.remove(t)
-    return res[::-1] if reverse else res
+def _pt_repr(o):
+    "Concise repr of plum types"
+    n = type(o).__name__
+    if n == 'Tuple': return f"{n.lower()}[{','.join(_pt_repr(t) for t in o._el_types)}]"
+    if n == 'List': return f'{n.lower()}[{_pt_repr(o._el_type)}]'
+    if n == 'Dict': return f'{n.lower()}[{_pt_repr(o._key_type)},{_pt_repr(o._value_type)}]'
+    if n in ('Sequence','Iterable'): return f'{n}[{_pt_repr(o._el_type)}]'
+    if n == 'VarArgs': return f'{n}[{_pt_repr(o.type)}]'
+    if n == 'Union': return '|'.join(sorted(t.__name__ for t in (o.get_types())))
+    assert len(o.get_types()) == 1
+    return o.get_types()[0].__name__
 
 # Cell
-def _chk_defaults(f, ann):
-    pass
-# Implementation removed until we can figure out how to do this without `inspect` module
-#     try: # Some callables don't have signatures, so ignore those errors
-#         params = list(inspect.signature(f).parameters.values())[:min(len(ann),2)]
-#         if any(p.default!=inspect.Parameter.empty for p in params):
-#             warn(f"{f.__name__} has default params. These will be ignored.")
-#     except ValueError: pass
-
-# Cell
-def _p2_anno(f):
-    "Get the 1st 2 annotations of `f`, defaulting to `object`"
-    hints = type_hints(f)
-    ann = [o for n,o in hints.items() if n!='return']
-    if callable(f): _chk_defaults(f, ann)
-    while len(ann)<2: ann.append(object)
-    return ann[:2]
+class FastFunction(Function):
+    def __repr__(self):
+        return '\n'.join(f"{f.__name__}: ({','.join(_pt_repr(t) for t in s.types)}) -> {_pt_repr(r)}"
+                         for s, (f, r) in self.methods.items())
 
-# Cell
-class _TypeDict:
-    def __init__(self): self.d,self.cache = {},{}
-
-    def _reset(self):
-        self.d = {k:self.d[k] for k in sorted_topologically(self.d, cmp=lenient_issubclass)}
-        self.cache = {}
-
-    def add(self, t, f):
-        "Add type `t` and function `f`"
-        if not isinstance(t, tuple): t = tuple(L(union2tuple(t)))
-        for t_ in t: self.d[t_] = f
-        self._reset()
-
-    def all_matches(self, k):
-        "Find first matching type that is a super-class of `k`"
-        if k not in self.cache:
-            types = [f for f in self.d if lenient_issubclass(k,f)]
-            self.cache[k] = [self.d[o] for o in types]
-        return self.cache[k]
-
-    def __getitem__(self, k):
-        "Find first matching type that is a super-class of `k`"
-        res = self.all_matches(k)
-        return res[0] if len(res) else None
-
-    def __repr__(self): return self.d.__repr__()
-    def first(self): return first(self.d.values())
+    @delegates(Function.dispatch)
+    def dispatch(self, f=None, **kwargs): return super().dispatch(_eval_annotations(f), **kwargs)
 
-# Cell
-class TypeDispatch:
-    "Dictionary-like object; `__getitem__` matches keys of types using `issubclass`"
-    def __init__(self, funcs=(), bases=()):
-        self.funcs,self.bases = _TypeDict(),L(bases).filter(is_not(None))
-        for o in L(funcs): self.add(o)
-        self.inst = None
-        self.owner = None
-
-    def add(self, f):
-        "Add type `t` and function `f`"
-        if isinstance(f, staticmethod): a0,a1 = _p2_anno(f.__func__)
-        else: a0,a1 = _p2_anno(f)
-        t = self.funcs.d.get(a0)
-        if t is None:
-            t = _TypeDict()
-            self.funcs.add(a0, t)
-        t.add(a1, f)
-
-    def first(self):
-        "Get first function in ordered dict of type:func."
-        return self.funcs.first().first()
-
-    def returns(self, x):
-        "Get the return type of annotation of `x`."
-        return anno_ret(self[type(x)])
-
-    def _attname(self,k): return getattr(k,'__name__',str(k))
-    def __repr__(self):
-        r = [f'({self._attname(k)},{self._attname(l)}) -> {getattr(v, "__name__", type(v).__name__)}'
-             for k in self.funcs.d for l,v in self.funcs[k].d.items()]
-        r = r + [o.__repr__() for o in self.bases]
-        return '\n'.join(r)
-
-    def __call__(self, *args, **kwargs):
-        ts = L(args).map(type)[:2]
-        f = self[tuple(ts)]
-        if not f: return args[0]
-        if isinstance(f, staticmethod): f = f.__func__
-        elif self.inst is not None: f = MethodType(f, self.inst)
-        elif self.owner is not None: f = MethodType(f, self.owner)
-        return f(*args, **kwargs)
-
-    def __get__(self, inst, owner):
-        self.inst = inst
-        self.owner = owner
-        return self
-
-    def __getitem__(self, k):
-        "Find first matching type that is a super-class of `k`"
-        k = L(k)
-        while len(k)<2: k.append(object)
-        r = self.funcs.all_matches(k[0])
-        for t in r:
-            o = t[k[1]]
-            if o is not None: return o
-        for base in self.bases:
-            res = base[k]
-            if res is not None: return res
-        return None
+    def __getitem__(self, ts):
+        "Return the most-specific matching method with fewest parameters"
+        ts = L(ts)
+        nargs = min(len(o) for o in self.methods.keys())
+        while len(ts) < nargs: ts.append(object)
+        return self.invoke(*ts)
 
 # Cell
-class DispatchReg:
-    "A global registry for `TypeDispatch` objects keyed by function name"
-    def __init__(self): self.d = defaultdict(TypeDispatch)
-    def __call__(self, f):
-        if isinstance(f, (classmethod, staticmethod)): nm = f'{f.__func__.__qualname__}'
-        else: nm = f'{f.__qualname__}'
-        if isinstance(f, classmethod): f=f.__func__
-        self.d[nm].add(f)
-        return self.d[nm]
-
-typedispatch = DispatchReg()
+class FastDispatcher(Dispatcher):
+    def _get_function(self, method, owner):
+        "Adapted from `Dispatcher._get_function` to use `FastFunction`"
+        name = method.__name__
+        if owner:
+            if owner not in self._classes: self._classes[owner] = {}
+            namespace = self._classes[owner]
+        else: namespace = self._functions
+        if name not in namespace: namespace[name] = FastFunction(method, owner=owner)
+        return namespace[name]
+
+    @delegates(Dispatcher.__call__, but='method')
+    def __call__(self, f, **kwargs): return super().__call__(_eval_annotations(f), **kwargs)
+
+    def _to(self, cls, nm, f, **kwargs):
+        nf = copy_func(f)
+        nf.__qualname__ = f'{cls.__name__}.{nm}' # plum uses __qualname__ to infer f's owner
+        pf = self(nf, **kwargs)
+        # plum uses __set_name__ to resolve a plum.Function's owner
+        # since we assign after class creation, __set_name__ must be called directly
+        # source: https://docs.python.org/3/reference/datamodel.html#object.__set_name__
+        pf.__set_name__(cls, nm)
+        pf = pf.resolve()
+        setattr(cls, nm, pf)
+        return pf
+
+    def to(self, cls):
+        "Decorator: dispatch `f` to `cls.f`"
+        def _inner(f, **kwargs):
+            nm = f.__name__
+            # check __dict__ to avoid inherited methods but use getattr so pf.__get__ is called, which plum relies on
+            if nm in cls.__dict__:
+                pf = getattr(cls, nm)
+                if not hasattr(pf, 'dispatch'): pf = self._to(cls, nm, pf, **kwargs)
+                pf.dispatch(f)
+            else: pf = self._to(cls, nm, f, **kwargs)
+            return pf
+        return _inner
+
+typedispatch = FastDispatcher()
 
 # Cell
 #nbdev_comment _all_=['cast']

fastcore/imports.py

@@ -1,5 +1,6 @@
 import sys,os,re,typing,itertools,operator,functools,math,warnings,functools,io,enum
 
+from copy import copy
 from operator import itemgetter,attrgetter
 from warnings import warn
 from typing import Iterable,Generator,Sequence,Iterator,List,Set,Dict,Union,Optional,Tuple
@@ -14,6 +15,15 @@
     MethodDescriptorType = type(str.join)
 from types import BuiltinFunctionType,BuiltinMethodType,MethodType,FunctionType,SimpleNamespace
 
+#Patch autoreload (if its loaded) to work with plum
+try: from IPython import get_ipython
+except ImportError: pass
+else:
+    ip = get_ipython()
+    if ip is not None and 'IPython.extensions.storemagic' in ip.extension_manager.loaded:
+        from plum.autoreload import activate
+        activate()
+
 NoneType = type(None)
 string_classes = (str,bytes)
 

fastcore/transform.py

@@ -9,34 +9,33 @@
 from .utils import *
 from .dispatch import *
 import inspect
+from plum import add_conversion_method
 
 # Cell
 _tfm_methods = 'encodes','decodes','setups'
 
+def _is_tfm_method(n, f): return n in _tfm_methods and callable(f)
+
 class _TfmDict(dict):
-    def __setitem__(self,k,v):
-        if k not in _tfm_methods or not callable(v): return super().__setitem__(k,v)
-        if k not in self: super().__setitem__(k,TypeDispatch())
-        self[k].add(v)
+    def __setitem__(self, k, v): super().__setitem__(k, typedispatch(v) if _is_tfm_method(k, v) else v)
 
 # Cell
 class _TfmMeta(type):
     def __new__(cls, name, bases, dict):
+        # _TfmMeta.__call__ shadows the signature of inheriting classes, set it back
         res = super().__new__(cls, name, bases, dict)
-        for nm in _tfm_methods:
-            base_td = [getattr(b,nm,None) for b in bases]
-            if nm in res.__dict__: getattr(res,nm).bases = base_td
-            else: setattr(res, nm, TypeDispatch(bases=base_td))
         res.__signature__ = inspect.signature(res.__init__)
         return res
 
     def __call__(cls, *args, **kwargs):
-        f = args[0] if args else None
-        n = getattr(f,'__name__',None)
-        if callable(f) and n in _tfm_methods:
-            getattr(cls,n).add(f)
-            return f
-        return super().__call__(*args, **kwargs)
+        f = first(args)
+        n = getattr(f, '__name__', None)
+        if _is_tfm_method(n, f): return typedispatch.to(cls)(f)
+        obj = super().__call__(*args, **kwargs)
+        # _TfmMeta.__new__ replaces cls.__signature__ which breaks the signature of a callable
+        # instances of cls, fix it
+        if hasattr(obj, '__call__'): obj.__signature__ = inspect.signature(obj.__call__)
+        return obj
 
     @classmethod
     def __prepare__(cls, name, bases): return _TfmDict()
@@ -60,13 +59,14 @@ def __init__(self, enc=None, dec=None, split_idx=None, order=None):
         self.init_enc = enc or dec
         if not self.init_enc: return
 
-        self.encodes,self.decodes,self.setups = TypeDispatch(),TypeDispatch(),TypeDispatch()
+        def identity(x): return x
+        for n in _tfm_methods: setattr(self,n,FastFunction(identity).dispatch(identity))
         if enc:
-            self.encodes.add(enc)
+            self.encodes.dispatch(enc)
             self.order = getattr(enc,'order',self.order)
             if len(type_hints(enc)) > 0: self.input_types = union2tuple(first(type_hints(enc).values()))
             self._name = _get_name(enc)
-        if dec: self.decodes.add(dec)
+        if dec: self.decodes.dispatch(dec)
 
     @property
     def name(self): return getattr(self, '_name', _get_name(self))
@@ -85,13 +85,24 @@ def _call(self, fn, x, split_idx=None, **kwargs):
     def _do_call(self, f, x, **kwargs):
         if not _is_tuple(x):
             if f is None: return x
-            ret = f.returns(x) if hasattr(f,'returns') else None
-            return retain_type(f(x, **kwargs), x, ret)
+            ts = [type(self),type(x)] if hasattr(f,'instance') else [type(x)]
+            _, ret = f.resolve_method(*ts)
+            ret = ret._type
+            # plum reads empty return annotation as object, retain_type expects it as None
+            if ret is object: ret = None
+            return retain_type(f(x,**kwargs), x, ret)
         res = tuple(self._do_call(f, x_, **kwargs) for x_ in x)
         return retain_type(res, x)
+    def encodes(self, x): return x
+    def decodes(self, x): return x
+    def setups(self, dl): return dl
 
 add_docs(Transform, decode="Delegate to <code>decodes</code> to undo transform", setup="Delegate to <code>setups</code> to set up transform")
 
+# Cell
+#Implement the Transform convention that a None return annotation disables conversion
+add_conversion_method(object, NoneType, lambda x: x)
+
 # Cell
 class InplaceTransform(Transform):
     "A `Transform` that modifies in-place and just returns whatever it's passed"