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54 | <H2><A NAME="SECTION0071540000000000000000"></A><A NAME="comparison-to-builtin-set"></A> | |
55 | <BR> | |
56 | 5.15.4 Comparison to the built-in <tt class="class">set</tt> types | |
57 | ||
58 | </H2> | |
59 | ||
60 | <P> | |
61 | The built-in <tt class="class">set</tt> and <tt class="class">frozenset</tt> types were designed based | |
62 | on lessons learned from the <tt class="module">sets</tt> module. The key differences are: | |
63 | ||
64 | <P> | |
65 | ||
66 | <UL> | |
67 | <LI><tt class="class">Set</tt> and <tt class="class">ImmutableSet</tt> were renamed to <tt class="class">set</tt> and | |
68 | <tt class="class">frozenset</tt>. | |
69 | </LI> | |
70 | <LI>There is no equivalent to <tt class="class">BaseSet</tt>. Instead, use | |
71 | <code>isinstance(x, (set, frozenset))</code>. | |
72 | </LI> | |
73 | <LI>The hash algorithm for the built-ins performs significantly better | |
74 | (fewer collisions) for most datasets. | |
75 | </LI> | |
76 | <LI>The built-in versions have more space efficient pickles. | |
77 | </LI> | |
78 | <LI>The built-in versions do not have a <tt class="method">union_update()</tt> method. | |
79 | Instead, use the <tt class="method">update()</tt> method which is equivalent. | |
80 | </LI> | |
81 | <LI>The built-in versions do not have a <tt class="method">_repr(sort=True)</tt> method. | |
82 | Instead, use the built-in <tt class="function">repr()</tt> and <tt class="function">sorted()</tt> | |
83 | functions: <code>repr(sorted(s))</code>. | |
84 | </LI> | |
85 | <LI>The built-in version does not have a protocol for automatic conversion | |
86 | to immutable. Many found this feature to be confusing and no one | |
87 | in the community reported having found real uses for it. | |
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125 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> | |
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