慢斯卡拉断言 [英] Slow Scala assert

问题描述

我们最近一直在分析代码，并且遇到了一些令人讨厌的热点.它们的格式为

We've been profiling our code recently and we've come across a few annoying hotspots. They're in the form

assert(a == b, a + " is not equal to " + b)

因为其中一些断言可以在代码中调用，所以字符串concat开始累加的次数很多. assert定义为:

Because some of these asserts can be in code called a huge amount of times the string concat starts to add up. assert is defined as:

def assert(assumption : Boolean, message : Any) = ....

为什么不定义为:

def assert(assumption : Boolean, message : => Any) = ....

这样，它就会懒惰地求值.鉴于尚未定义该方法，是否存在一种内联方法来调用带有惰性评估的消息参数的assert?

That way it would evaluate lazily. Given that it's not defined that way is there an inline way of calling assert with a message param that is evaluated lazily?

谢谢

推荐答案

惰性求值对于创建的函数对象也有一些开销.如果您的消息对象已经完全构造(静态消息)，则此开销是不必要的.

Lazy evaluation has also some overhead for the function object created. If your message object is already fully constructed (a static message) this overhead is unnecessary.

适合您的用例的方法是sprintf样式:

The appropriate method for your use case would be sprintf-style:

assert(a == b,  "%s is not equal to %s", a, b)

只要有特殊功能

assert(Boolean, String, Any, Any)

此实现没有开销，也没有var args数组的开销

this implementation has no overhead or the cost of the var args array

assert(Boolean, String, Any*)

一般情况.

实施toString会被延迟评估，但不可读:

Implementing toString would be evaluated lazily, but is not readable:

assert(a == b, new { override def toString =  a + " is not equal to " + b })

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