package Foo;
sub new {
    my ($type) = @_;
    return bless {},$type;
}

package Bar;
use Moose;

package Baz;
use Moose;
use MooseX::Method::Signatures;

method exec1 (Foo $f,Bar $b) {
    ...;
}
method exec2 ($f where {$_->isa('Foo')},Bar $b) {
    ...;
}

我发现exec2可以工作,但对于exec1,存在编译时错误.如果Foo是Mouse对象(这些是我无法更改的类),则会发生同样的错误.

'Foo' could not be parsed to a type constraint - maybe you need to pre-declare the type with class_type at C:/strawberry/perl/site/lib/Parse/Method/Signatures/TypeConstraint.pm line 74

但有没有办法可以使用exec1签名？