"Illegally post-declared types" 循环 class 定义

Question

Rakudo 版本 2020.01

这不编译。

use v6;

class N1 {}
class T1 {}

class G1 {
    has @.g is required where A1|Q1;
}

class Q1 {
    has $.q is required where N1|T1|G1;
}

class A1 {
    has Q1 @.a is required;
}

===SORRY!=== Error while compiling …
Illegally post-declared types:
    A1 used at line 7
    Q1 used at line 7

我认为只在 G1 之前声明标识符会对我有所帮助，但这也失败了：

===SORRY!=== Error while compiling …
Too late for unit-scoped class definition;
Please use the block form.
…:6
------> class A1;⏏ class Q1;

如何让它发挥作用？

Answer 1

可以，但是您需要将 classes 定义为存根。

class A { }

将只定义一个空 class。鉴于：

class A { ... }   # note the yadayadayada

将定义一个存根。所以添加：

class A1 { ... }
class Q1 { ... }

到您代码的顶部，应该可以解决问题。

"Illegally post-declared types" 循环 class 定义

"Illegally post-declared types" with circular class definition

porting

raku