哪个是最佳实践？冗余循环，还是在语句中调用相同的循环？

发布于 2025-01-21 19:42:24 字数 677 浏览 2 评论 0 原文

我正在学习如何编写最佳和最可读的代码。我写这本书的第一种方式具有冗余的陆面，但仅检查一次驱逐政策。虽然我的第二种方式没有循环的冗余，但请检查每次迭代的驱逐政策。有没有更好的方法来编写此代码？

    if self.remainingSpace - content.size < 0:
        if evictionPolicy == 'lru':
            while self.remainingSpace - content.size < 0:
                self.lruEvict()
        else:
            while self.remainingSpace - content.size < 0:
                self.mruEvict()

或者

    if self.remainingSpace - content.size < 0:
        while self.remainingSpace - content.size < 0:
            if evictionPolicy == 'lru':
                self.lruEvict()
            else:
                self.mruEvict()

原文

I'm in the process of learning how to write the most optimal and readable code. The first way I wrote this has redundant for-loops but only checks eviction policy once. While my second way doesn't have redundant for loops but checks the eviction policy every iteration. Is there a better way to write this code?

    if self.remainingSpace - content.size < 0:
        if evictionPolicy == 'lru':
            while self.remainingSpace - content.size < 0:
                self.lruEvict()
        else:
            while self.remainingSpace - content.size < 0:
                self.mruEvict()

    if self.remainingSpace - content.size < 0:
        while self.remainingSpace - content.size < 0:
            if evictionPolicy == 'lru':
                self.lruEvict()
            else:
                self.mruEvict()

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心的憧憬 2025-01-28 19:42:24

最简单，最快的版本。由于 emectionPolicy 永远不会更改，因此请先选择方法，以通用名称放置，然后使用单个公共循环：

evict = self.lruEvict if evictionPolicy == 'lru' else self.mruEvict

while self.remainingSpace - content.size < 0:  # As noted on the other answer, self.remainingSpace < content.size would be slightly more efficient
    evict()

无代码加倍，无运行时重复检查调用每个循环的方法。

Simplest and fastest version. Since evictionPolicy never changes, select the method up front, put it in a common name, then use a single common loop:

evict = self.lruEvict if evictionPolicy == 'lru' else self.mruEvict

while self.remainingSpace - content.size < 0:  # As noted on the other answer, self.remainingSpace < content.size would be slightly more efficient
    evict()

No doubling of code, no runtime repeated checks for which method to call on each loop.

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溺ぐ爱和你が 2025-01-28 19:42:24

正如 @Olivier-Melançon所述，如果循环仅在这种情况下，您就不需要第一个，因为 循环仅进入。

第一个版本更有效，但是如果 self.lruevict（）或 self.mruevict（）很昂贵，那么节省效率的节省可能会忽略不计：

    if evictionPolicy == 'lru':
        while self.remainingSpace < content.size:
            self.lruEvict()
    else:
        while self.remainingSpace < content.size:
            self.mruEvict()

第二个是更多可读性IMO：

    while self.remainingSpace < content.size:
        if evictionPolicy == 'lru':
            self.lruEvict()
        else:
            self.mruEvict()

另一个选项，它将与第二个选项具有相同的效率，更简洁，但也许更晦涩：

    while self.remainingSpace < content.size:
        self.lruEvict() if evictionPolicy == 'lru' else self.mruEvict()

当您使用 thing_if_true时，如果条件else thite thing_if_false python中的ternary ocerator， thing_if_true 仅在条件是真实的情况下才能计算或运行。

编辑：通过交换 content.size 删除 - 运算符到＆lt; 的右侧，因为如果我们是微观优化，它使用不必要的开销，此外，代码看起来更好。

As @olivier-melançon mentioned, you don't need the first if statmement, since the while loop only enters in that case anyway.

The first version is more efficient, but if either self.lruEvict() or self.mruEvict() are expensive, then the efficiency savings may be negligible:

    if evictionPolicy == 'lru':
        while self.remainingSpace < content.size:
            self.lruEvict()
    else:
        while self.remainingSpace < content.size:
            self.mruEvict()

The second is more readable IMO:

    while self.remainingSpace < content.size:
        if evictionPolicy == 'lru':
            self.lruEvict()
        else:
            self.mruEvict()

Another option which would be the same efficiency as the second option, more concise, but perhaps a bit more obscure:

    while self.remainingSpace < content.size:
        self.lruEvict() if evictionPolicy == 'lru' else self.mruEvict()

When you use the thing_if_true if condition else thing_if_false ternary operator in Python, the thing_if_true only gets calculated or run if condition is truthy, and thing_if_false only gets calculated or run if condition is falsey.

Edit: Removed the - operator by swapping content.size to the right side of the <, since if we're micro-optimizing, it uses unnecessary overhead, and moreover the code looks nicer w/o it.