我有一个脚本和一个像这样的包：
# file: sortscript.pl
use strict;
use warnings;
use SortPackage;
my @arrays = ([1,"array1"],[10,"array3"],[4,"array2"]);
print "Using sort outside package\n";
foreach (sort SortPackage::simplesort @arrays){
print $_->[1],"\n";
}
print "\nUsing sort in same package\n";
SortPackage::sort_from_same_package(@arrays);
–
# file: SortPackage.pm
use strict;
use warnings;
package SortPackage;
sub simplesort{
return ($a->[0] <=> $b->[0]);
}
sub sort_from_same_package{
my @arrs = @_;
foreach (sort simplesort @arrs){
print $_->[1],"\n";
}
}
1;
$perl sortscript.pl Using sort outside package Use of uninitialized value in numeric comparison (<=>) at SortPackage.pm line 15. Use of uninitialized value in numeric comparison (<=>) at SortPackage.pm line 15. Use of uninitialized value in numeric comparison (<=>) at SortPackage.pm line 15. Use of uninitialized value in numeric comparison (<=>) at SortPackage.pm line 15. Use of uninitialized value in numeric comparison (<=>) at SortPackage.pm line 15. Use of uninitialized value in numeric comparison (<=>) at SortPackage.pm line 15. array1 array3 array2 Using sort in same package array1 array2 array3
为什么我无法正确使用子例程在其他包中进行排序？
解决方法
如前所述,$a和$b是包全局变量,因此另一种解决方案是将调用站点的全局变量暂时别名为SortPackage包中的全局变量：
{
local (*a,*b) = (*SortPackage::a,*SortPackage::b);
foreach (sort SortPackage::simplesort @arrays){
print $_->[1],"\n";
}
}
但当然,这非常难看.我只是让SortPackage导出一个完整的排序例程,而不仅仅是一个比较器：
package SortPackage;
use strict;
sub _sort_by_first_element_comparator {
return $a->[0] <=> $b->[0];
}
sub sort_by_first_element {
return sort _sort_by_first_element_comparator @_;
}