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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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