我模糊地回顾,警告的pragma应该在我们正在加载使用的模块的列表中最后.我也模糊地记得,它与模块注册自己的警告类别有关,但我无法重现任何问题.有人可以指向相关文章,还是显示一个示例,其中警告标注的位置有何区别？
解决方法
这可能是你所指的.无论哪种方式,都需要注意,我将其作为一个错误提交
我/ Warnings.pm
package My::Warnings;
use warnings::register;
sub test {
warnings::warnif 'This is my warning';
}
1;
main.pl
use strict;
use feature 'switch';
use warnings 'all';
use My::Warnings;
print undef;
given (1) { }
My::Warnings::test();
如预期的那样,这将产生
given is experimental at E:\Perl\source\main.pl line 10. Use of uninitialized value in print at E:\Perl\source\main.pl line 8. This is my warning at E:\Perl\source\main.pl line 12.
但是,如果任何警告类别被禁用,它也将禁用自定义类别.喜欢这个
use strict;
use feature 'switch';
use warnings 'all';
no warnings 'experimental';
use My::Warnings;
print undef;
given (1) { }
My::Warnings::test();
这只输出
Use of uninitialized value in print at E:\Perl\source\main.pl line 9.
并且似乎有必要在使用My :: Warnings之后启用警告以使其执行
use strict;
use feature 'switch';
use My::Warnings;
use warnings 'all';
no warnings 'experimental';
print undef;
given (1) { }
My::Warnings::test();
产生
Use of uninitialized value in print at E:\Perl\source\main.pl line 9. This is my warning at E:\Perl\source\main.pl line 13.
更新
这样的东西
use strict;
use feature 'switch';
use warnings 'all';
no warnings 'experimental';
use warnings 'experimental';
use My::Warnings;
print undef;
given (1) { }
My::Warnings::test();
打印
given is experimental at E:\Perl\source\main.pl line 12. Use of uninitialized value in print at E:\Perl\source\main.pl line 10.