问题描述
我想知道为什么ruby给and，or的优先级低于&&，||并分配运算符?有什么理由吗?
I wonder why ruby give and, or less precedence than &&, || , and assign operator? Is there any reason?
推荐答案
我的猜测是，这直接来自Perl.在特定情况下，需要较低优先级的情况下，在Perl 5中后来添加了or和and运算符.
My guess is that's a direct carry-over from Perl. The operators or and and were added later in Perl 5 for specific situations were lower precedence was desired.
例如，在Perl中，我们希望||具有较低的优先级，以便我们可以编写:
For example, in Perl, here we wish that || had lower precedence, so that we could write:
try to perform big long hairy complicated action || die ;
，并确保||不会吞噬动作的一部分.正是出于这个目的，Perl 5引入了or，这是||的新版本，它的优先级较低.
and be sure that the || was not going to gobble up part of the action. Perl 5 introduced or, a new version of || that has low precedence, for exactly this purpose.
在Ruby中可以使用or但不能使用||的示例:
An example in Ruby where you could use or but not ||:
value = possibly_false or raise "foo"
如果使用||，则可能是语法错误.
If you used ||, it would be a syntax error.
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