I got an unexpected demonstration of the double dispatch pattern in real life the other day.

几天前在实际生活中我意外地得到了双重分发模式的一个演示。

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We can use a pattern called Double Dispatch to pull out the variation into the subclasses in such a way that we don't break existing interface contracts.

我们可以使用称为双重分发的模式将变化推入子类中，通过这种方式，我们不需要破坏现有的接口定义。

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Note that evaluate returns a Double, which means that each case in the pattern match is going to have to evaluate into a Double value.

注意evaluate返回了一个Double，它意味着模式匹配中的每一个case都必须被求值成一个double值。

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Prices are now in a three-week-old downtrend on the daily bar chart and the specter of a bearish double-top reversal pattern on the daily chart has resurfaced.

FORBES: P.M. Kitco Metals Roundup: Comex Gold Hammered Lower on Strong U.S. Dollar, Lower Crude Oil, Margin-Call Selling

Some fresh near-term technical damage was inflicted Thursday to raise the specter of a bearish double-top reversal pattern forming on the daily bar chart.

FORBES: A.M. Kitco Metals Roundup: Comex Gold Sharply Lower as U.S. Dollar Index Soars, Crude Oil Slumps following FOMC

But the bulls do not want to see follow-through selling pressure on Friday to produce a bearish weekly low close and raise the specter of a bearish double-top reversal pattern forming on the daily bar chart.

FORBES: P.M. Kitco Metals Roundup: Comex Gold Ends Sharply Lower on Uptick in Investor Risk Appetite, Technically Related Selling