我是Perl的新人,在工作中遇到了这段代码,我搜索了一段时间,但没有找到答案.任何人都可以用简单的英文解释其功能吗?谢谢.
my $abc = delete $args{ 'abc' } // croak 'some information!';
解决方法
从此页面:
http://perldoc.perl.org/perlop.html#Logical-Defined-Or
@H_502_8@
Although it has no direct equivalent in C,Perl’s //
operator is related to its C-style or
. In fact,it’s exactly the same as ||
,except that it tests the left hand side’s @H_301_16@definedness instead of its @H_301_16@truth. Thus,EXPR1 // EXPR2
returns the value of EXPR1
if it’s defined,otherwise,the value of EXPR2
is returned. (EXPR1
is evaluated in scalar context,EXPR2
in the context of //
itself). Usually,this is the same result as defined(EXPR1) ? EXPR1 : EXPR2
(except that the ternary-operator form can be used as a lvalue,while EXPR1 // EXPR2
cannot). This is very useful for providing default values for variables. If you actually want to test if at least one of $a
and $b
is defined,use defined($a // $b)
.