如果答案已经确定，Perl是否经过优化以跳过剩余的逻辑操作数? [英] Is Perl optimized to skip remaining logic operands if the answer is already decided?

问题描述

例如，如果$do eq 'b'，我需要匹配一些文本. 如果我运行此代码:

if (($do eq 'b') && (/text/))
{
do stuff
}

如果第一个括号为假，perl是否会评估第一个括号和第二个括号，或者在第二个括号的评估中停止它?

后续问题此处. (我不知道该提一个新问题还是将其发布在这里)

解决方案

是.这种行为通常在惯用的perl中使用.

考虑:

open FILE, ">$fname" or die $!;

如果打开文件没有错误(open返回true)，则不执行die语句.这不是die例程的特殊处理；这只是perl处理逻辑评估的方式.

For instance, I need to match some text if $do eq 'b'. If I run this code:

if (($do eq 'b') && (/text/))
{
do stuff
}

Would perl evaluate the first parenthesis and second parenthesis no matter what or would it stop at the evaluation of the second parenthesis if the first parenthesis was false?

Follow-up question here. (I didn't know if I should make a new question or post it here)

解决方案

Yes. This behavior is commonly used in idiomatic perl.

Consider:

open FILE, ">$fname" or die $!;

If there is no error opening the file (open returns true), the die statement is not executed. This is not special treatment of the die routine; it is just the way perl handles logic evaluation.

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