Made save() fit on a page, while adding comments. (I moved some type
checks to save_reduce(), which can also be called from a subclass.) Also tweaked some more comments.
This commit is contained in:
Guido van Rossum
parent
ad5a771fae
commit
bc64e22ed6
127
Lib/pickle.py
127
Lib/pickle.py
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@ -32,6 +32,7 @@ import marshal
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import sys
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import struct
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import re
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import warnings
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__all__ = ["PickleError", "PicklingError", "UnpicklingError", "Pickler",
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"Unpickler", "dump", "dumps", "load", "loads"]
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@ -39,7 +40,7 @@ __all__ = ["PickleError", "PicklingError", "UnpicklingError", "Pickler",
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# These are purely informational; no code usues these
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format_version = "2.0" # File format version we write
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compatible_formats = ["1.0", # Original protocol 0
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"1.1", # Protocol 0 with class supprt added
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"1.1", # Protocol 0 with INST added
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"1.2", # Original protocol 1
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"1.3", # Protocol 1 with BINFLOAT added
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"2.0", # Protocol 2
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@ -249,104 +250,113 @@ class Pickler:
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return GET + `i` + '\n'
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def save(self, obj):
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# Check for persistent id (defined by a subclass)
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pid = self.persistent_id(obj)
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if pid is not None:
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if pid:
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self.save_pers(pid)
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return
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memo = self.memo
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d = id(obj)
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if d in memo:
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self.write(self.get(memo[d][0]))
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# Check the memo
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x = self.memo.get(id(obj))
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if x:
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self.write(self.get(x[0]))
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return
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# Check the type dispatch table
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t = type(obj)
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try:
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f = self.dispatch[t]
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except KeyError:
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pass
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else:
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f(self, obj)
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f = self.dispatch.get(t)
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if f:
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f(self, obj) # Call unbound method with explicit self
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return
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# The dispatch table doesn't know about type t.
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# Check for a class with a custom metaclass; treat as regular class
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try:
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issc = issubclass(t, TypeType)
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except TypeError: # t is not a class
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except TypeError: # t is not a class (old Boost; see SF #502085)
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issc = 0
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if issc:
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self.save_global(obj)
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return
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try:
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reduce = dispatch_table[t]
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except KeyError:
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try:
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reduce = obj.__reduce__
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except AttributeError:
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raise PicklingError, \
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"can't pickle %s object: %s" % (`t.__name__`,
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`obj`)
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else:
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tup = reduce()
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# Check copy_reg.dispatch_table
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reduce = dispatch_table.get(t)
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if reduce:
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rv = reduce(obj)
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else:
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tup = reduce(obj)
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# Check for __reduce__ method
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reduce = getattr(obj, "__reduce__", None)
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if not reduce:
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raise PicklingError("Can't pickle %r object: %r" %
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(t.__name__, obj))
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rv = reduce()
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if type(tup) is StringType:
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self.save_global(obj, tup)
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# Check for string returned by reduce(), meaning "save as global"
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if type(rv) is StringType:
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self.save_global(obj, rv)
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return
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if type(tup) is not TupleType:
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raise PicklingError, "Value returned by %s must be a " \
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"tuple" % reduce
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# Assert that reduce() returned a tuple
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if type(rv) is not TupleType:
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raise PicklingError("%s must return string or tuple" % reduce)
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l = len(tup)
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if (l != 2) and (l != 3):
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raise PicklingError, "tuple returned by %s must contain " \
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"only two or three elements" % reduce
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callable = tup[0]
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arg_tup = tup[1]
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if l > 2:
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state = tup[2]
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else:
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# Assert that it returned a 2-tuple or 3-tuple, and unpack it
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l = len(rv)
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if l == 2:
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func, args = rv
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state = None
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elif l == 3:
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func, args, state = rv
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else:
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raise PicklingError("Tuple returned by %s must have "
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"exactly two or three elements" % reduce)
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if type(arg_tup) is not TupleType and arg_tup is not None:
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raise PicklingError, "Second element of tuple returned " \
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"by %s must be a tuple" % reduce
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self.save_reduce(callable, arg_tup, state)
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# Save the reduce() output and finally memoize the object
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self.save_reduce(func, args, state)
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self.memoize(obj)
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def persistent_id(self, obj):
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# This exists so a subclass can override it
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return None
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def save_pers(self, pid):
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# Save a persistent id reference
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if self.bin:
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self.save(pid)
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self.write(BINPERSID)
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else:
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self.write(PERSID + str(pid) + '\n')
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def save_reduce(self, acallable, arg_tup, state = None):
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write = self.write
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def save_reduce(self, func, args, state=None):
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# This API is be called by some subclasses
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# Assert that args is a tuple or None
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if not isinstance(args, TupleType):
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if args is None:
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# A hack for Jim Fulton's ExtensionClass, now deprecated.
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# See load_reduce()
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warnings.warn("__basicnew__ special case is deprecated",
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DeprecationWarning)
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else:
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raise PicklingError(
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"args from reduce() should be a tuple")
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# Assert that func is callable
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if not callable(func):
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raise PicklingError("func from reduce should be callable")
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save = self.save
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write = self.write
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if not callable(acallable):
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raise PicklingError("__reduce__() must return callable as "
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"first argument, not %s" % `acallable`)
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save(acallable)
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save(arg_tup)
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save(func)
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save(args)
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write(REDUCE)
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if state is not None:
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save(state)
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write(BUILD)
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# Methods below this point are dispatched through the dispatch table
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dispatch = {}
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def save_none(self, obj):
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@ -1028,9 +1038,8 @@ class Unpickler:
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"unpickling" % callable
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if arg_tup is None:
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import warnings
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warnings.warn("The None return argument form of __reduce__ is "
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"deprecated. Return a tuple of arguments instead.",
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# A hack for Jim Fulton's ExtensionClass, now deprecated
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warnings.warn("__basicnew__ special case is deprecated",
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DeprecationWarning)
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value = callable.__basicnew__()
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else:
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