以星号 * 开头的 Perl 标识符代表什么? [英] What do Perl identifiers starting with an asterisk * represent?

问题描述

我有这个子程序，它的标识符定义如下

I have this sub-routine which has identifiers defined like

*VALID_NAME_REG_EX = \"[ a-zA-Z0-9_#.:@=-]+";
*MACRO_VALID_NAME  = \"MACRO_VALID_NAME";

我进一步查看了文件.它们被引用为 $MACRO_VALID_NAME.

I looked into the file further. They are referenced as $MACRO_VALID_NAME.

我猜它是用字符串右侧的值替换了该值，但我不确定这一点并需要确认.

I guess it's substituting the value with right side of string, but I am not sure of this and want a confirmation.

推荐答案

*VALID_NAME_REG_EX = \"[ a-zA-Z0-9_#.:@=-]+";

这样做的效果是将 $VALID_NAME_REG_EX 指定为 Perl 字符串文字的标识符 "[ a-zA-Z0-9_#.:@=-]+"

The effect this has is to assign $VALID_NAME_REG_EX as an identifier for the Perl string literal "[ a-zA-Z0-9_#.:@=-]+"

这和说的不一样

$VALID_NAME_REG_EX = "[ a-zA-Z0-9_#.:@=-]+"

将字符串复制到分配给$VALID_NAME_REG_EX的空间，以便以后可以更改

which copies the string into the space assigned to $VALID_NAME_REG_EX so it may later be altered

Perl 文字必须是只读的才能有意义，因此赋值的结果是使 $VALID_NAME_REG_EX 成为一个 只读 变量，也称为一个常数.如果您尝试分配给它，您将收到类似

Perl literals have to be read-only to make any sense, so the result of the assignment is to make $VALID_NAME_REG_EX a read-only variable, otherwise known as a constant. If you try assigning to it you will get a message something like

尝试修改只读值

这篇关于以星号 * 开头的 Perl 标识符代表什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！