数学家在过去数百年中已经证明，类对于这些目的就已经足够：它们可以担负起数、函数和其他抽象对象的任务。

But mathematicians have established in the past hundred years that classes, or sets, are enough for all these purposes: they can be made to do the work of Numbers, functions, and the rest.

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对于被调用方函数，为此函数中由当前函数调用的实例所分配的对象数。

For a callee function, the number of objects that were allocated by the instances of this function that were called by the current function.

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对于被调用方函数，为此函数中由当前函数调用的实例所创建的对象数。

For a callee function, the number of objects that were created by the instances of this function that were called by the current function.

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