带胖逗号的 perl 散列

Question

我读过在为哈希定义键值时使用宽逗号，我们不需要在键周围放置 quotes '' 来指示它是一个字符串。但是，我发现如果我在键周围包含 quotes，它仍然可以正常工作，就好像它忽略了 '' 一样。

下面的声明可以安全使用吗？

$result = { 
     'Bill' => { Java => 56, C => 78, Perl => 90 } , 
     'Mary' => { Java => 82, C => 65, Perl => PX, Python => 72},
};

Answer 1

在使用粗逗号时，您不需要使用单引号，如果您愿意，可以可以。它是可选的。

胖逗号只是一个逗号，唯一的区别是如果存在一个裸词，一个没有引号的词，那么它将把这个裸词当作单引号。

来自 perlop :

The => operator is a synonym for the comma except that it causes a word on its left to be interpreted as a string if it begins with a letter or underscore and is composed only of letters, digits and underscores. This includes operands that might otherwise be interpreted as operators, constants, single number v-strings or function calls. If in doubt about this behavior, the left operand can be quoted explicitly.