<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Feb 29, 2012, at 4:23 PM, Victor Stinner wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">One of my colleagues implemented recently its own frozendict class<br>(which the "frozendict" name ;-)</span></blockquote><br></div><div>I write new collection classes all the time.</div><div>That doesn't mean they warrant inclusion in the library or builtins.</div><div>There is a use case for ListenableSets and ListenableDicts -- do we</div><div>need them in the library? I think not. How about case insensitive variants?</div><div>I think not. There are tons of recipes on ASPN and on PyPI. </div><div>That doesn't make them worth adding in to the core group of types.</div><div><br></div><div>As core developers, we need to place some value on language </div><div>compactness and learnability. The language has already gotten</div><div>unnecessarily fat -- it is the rare Python programmer who knows</div><div>set operations on dict views, new-style formatting, abstract base classes,</div><div>contextlib/functools/itertools, how the with-statement works, </div><div>how super() works, what properties/staticmethods/classmethods are for,</div><div>differences between new and old-style classes, Exception versus BaseException,</div><div>weakreferences, __slots__, chained exceptions, etc.</div><div><br></div><div>If we were to add another collections type, it would need to be something</div><div>that powerfully adds to the expressivity of the language. Minor variants </div><div>on what we already have just makes that language harder to learn and remember</div><div>but not providing much of a payoff in return.</div><div><br></div><div><br></div><div>Raymond</div><br></body></html>