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SF bug #663701: sets module review

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Renamed hook methods to use the double underscore convention.
This commit is contained in:
Raymond Hettinger 2003-02-14 03:42:11 +00:00
parent e544f6f682
commit 2835e37be5
2 changed files with 11 additions and 11 deletions
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8
Doc/lib/libsets.tex
View file

@ -203,23 +203,23 @@ before being added as a set element.
The mechanism is to always add a hashable element, or if it is not
hashable, the element is checked to see if it has an
\method{_as_immutable()} method which returns an immutable equivalent.
\method{__as_immutable__()} method which returns an immutable equivalent.
Since \class{Set} objects have a \method{_as_immutable()} method
Since \class{Set} objects have a \method{__as_immutable__()} method
returning an instance of \class{ImmutableSet}, it is possible to
construct sets of sets.
A similar mechanism is needed by the \method{__contains__()} and
\method{remove()} methods which need to hash an element to check
for membership in a set. Those methods check an element for hashability
and, if not, check for a \method{_as_temporarily_immutable()} method
and, if not, check for a \method{__as_temporarily_immutable__()} method
which returns the element wrapped by a class that provides temporary
methods for \method{__hash__()}, \method{__eq__()}, and \method{__ne__()}.
The alternate mechanism spares the need to build a separate copy of
the original mutable object.
\class{Set} objects implement the \method{_as_temporarily_immutable()}
\class{Set} objects implement the \method{__as_temporarily_immutable__()}
method which returns the \class{Set} object wrapped by a new class
\class{_TemporarilyImmutableSet}.

14
Lib/sets.py
View file

@ -248,7 +248,7 @@ class BaseSet(object):
try:
return element in self._data
except TypeError:
transform = getattr(element, "_as_temporarily_immutable", None)
transform = getattr(element, "__as_temporarily_immutable__", None)
if transform is None:
raise # re-raise the TypeError exception we caught
return transform() in self._data
@ -325,7 +325,7 @@ class BaseSet(object):
data[element] = value
return
except TypeError:
transform = getattr(element, "_as_immutable", None)
transform = getattr(element, "__as_immutable__", None)
if transform is None:
raise # re-raise the TypeError exception we caught
data[transform()] = value
@ -335,7 +335,7 @@ class BaseSet(object):
try:
data[element] = value
except TypeError:
transform = getattr(element, "_as_immutable", None)
transform = getattr(element, "__as_immutable__", None)
if transform is None:
raise # re-raise the TypeError exception we caught
data[transform()] = value
@ -464,7 +464,7 @@ class Set(BaseSet):
try:
self._data[element] = True
except TypeError:
transform = getattr(element, "_as_immutable", None)
transform = getattr(element, "__as_immutable__", None)
if transform is None:
raise # re-raise the TypeError exception we caught
self._data[transform()] = True
@ -477,7 +477,7 @@ class Set(BaseSet):
try:
del self._data[element]
except TypeError:
transform = getattr(element, "_as_temporarily_immutable", None)
transform = getattr(element, "__as_temporarily_immutable__", None)
if transform is None:
raise # re-raise the TypeError exception we caught
del self._data[transform()]
@ -496,11 +496,11 @@ class Set(BaseSet):
"""Remove and return an arbitrary set element."""
return self._data.popitem()[0]
def _as_immutable(self):
def __as_immutable__(self):
# Return a copy of self as an immutable set
return ImmutableSet(self)
def _as_temporarily_immutable(self):
def __as_temporarily_immutable__(self):
# Return self wrapped in a temporarily immutable set
return _TemporarilyImmutableSet(self)