如何显示值的类型层次结构？

Question

在 Perl5 和 Moose 中，线性 isa 或 线性化 isa 有助于理解 class 层次结构。

方法WHAT显示值的具体类型：

> 42.WHAT
(Int)

如何显示类似

的内容

> 42.hypothetical-type-hierarchy
(Int) ┬ is (Cool) ─ is (Any) ─ is (Mu)
      └ does (Real) ─ does (Numeric)

…可能为每个使用的角色添加更多行？

编辑：具有两个角色的示例

class Beta {}
role Delta {}
role Gamma does Delta {}
role Eta {}
role Zeta does Eta {}
role Epsilon does Zeta {}
class Alpha is Beta does Gamma does Epsilon {}

# (Alpha) ┬ is (Beta)
#         ├ does (Gamma) ─ does (Delta)
#         └ does (Epsilon) ─ does (Zeta) ─ does (Eta)

my $ai = Alpha.new
$ai.^mro        # ((Alpha) (Beta) (Any) (Mu))

$ai.^roles      # ((Epsilon) (Zeta) (Eta) (Gamma) (Delta))
                # flat list, not two-element list of a tuple and triple‽

Answer 1

您可以使用

查询元对象

> 42.^mro
((Int) (Cool) (Any) (Mu))

其中mro代表方法解析顺序和

> 42.^roles
((Real) (Numeric))

您可以通过副词 :local（排除从父类继承的角色 - 仅适用于类）和 :!transitive（排除角色通过另一个角色组成 - 可用于两个角色和类).

以下应该可以帮助您入门：

my $depth = 0;
for Alpha.^mro {
    say "is {.^name}";
    (sub {
        ++$depth;
        for @_ {
            say '  ' x $depth ~ "does {.^name}";
            &?ROUTINE(.^roles(:!transitive)); # recursive call of anon sub
        }
        --$depth;
    })(.^roles(:local, :!transitive));
}

根据您的示例代码稍作修改

role Delta {}
role Gamma does Delta {}
role Eta {}
role Zeta does Eta {}
role Epsilon does Zeta {}
class Beta does Gamma {}
class Alpha is Beta does Gamma does Epsilon {}

它产生输出

is Alpha
  does Epsilon
    does Zeta
      does Eta
  does Gamma
    does Delta
is Beta
  does Gamma
    does Delta
is Any
is Mu

如何显示值的类型层次结构？

How do you show the type hierarchy of a value?

raku

mop