有人知道解析或优先级决定是否导致“不使用括号”的“使用”转移是不明确的“,代码如下：
shift . 'some string'; # and not (shift) . 'some string'; # or shift() . 'some string';
这是否有意使某些句法结构更容易？还是仅仅是Perl解析器工作的方法呢？
注意：这是关于语言设计的讨论,而不是一个建议的地方
"@{[shift]}some string"
解决方法
使用诊断程序,您将获得有用的信息：
Warning: Use of "shift" without parentheses is ambiguous at (eval
9)[/usr/lib/perl5/5.8/perl5db.pl:628] line 2 (#1)
(S ambiguous) You wrote a unary operator followed by something that
looks like a binary operator that could also have been interpreted as a
term or unary operator. For instance,if you know that the rand
function has a default argument of 1.0,and you write
rand + 5;
you may THINK you wrote the same thing as
rand() + 5;
but in actual fact,you got
rand(+5);
So put in parentheses to say what you really mean.
恐惧是你可以写一些像shift.5这样的东西,它将被解析为shift(0.5).