dart - 格式错误的类型:…在这种情况下使用 'some-object'无效

Question

我不确定是什么问题，还是运行时错误试图告诉我。我有一个试图在类的构造期间分配对象的类，但是，出现以下运行时错误:

malformed type: line 150 pos 26: using 'type_tree' in this context is invalid _output_type = new **type_tree.asUnknown();**

因此，我在构造期间无法分配的类思维上添加了一种测试方法:

class X {
  X() {
    type_tree doh = new type_tree.asUnknown();    <--- runtime error
  }
  void bogus() {
    type_tree output_type = new type_tree.asUnknown();
  }
}
...
X x = new X();
x.bogus();    <-- runtime error as well

但是我可以在类之外分配 type_tree 对象:

type_tree obj = new type_tree.asUnknown();    <-- works

我以前从未遇到过这种类型的运行时错误，也无法弄清楚问题出在哪里。关于寻找什么的任何想法？

下面是该代码的更详细的版本。

type_tree.dart

part of OpenCog.moses;
class type_tree extends NTree<type_node> {
  // Basic named constructors
  type_tree.asUnknown() {...}
  type_tree.asIllFormed() {...}

}

procedure_call_base.dart

part of OpenCog.moses;
class ProcedureCallBase extends operator_base {
  type_tree _output_type;
  factory ProcedureCallBase.from(...) {
     ProcedureCallBase(String name, int arity, combo_tree tr,
        [bool infer_type = false]) : super(name),
       _arity = arity,
       _body = tr {
       _output_type = new type_tree.asUnknown();  <-- runtime error
     }

    ...
    ProcedureCallBase v = new ProcedureCallBase(name, arity, tr, infer_type);
    return v;
  }
  // A test method called in unit test.
  void bogus() {
    type_tree output_type = new type_tree.asUnknown();  <-- also fails at runtime
  }

}

单元测试代码:

    test("Check valid definition", () {
      String proc = r"add(2) := +($1 $2)";

      ProcedureCallBase v = new ProcedureCallBase.from(proc); <-- fails in the constructor
      v.bogus();   <-- fails inside bogus method
    });

    test("Check type tree", () {
      type_tree doh = new type_tree.asUnknown();  <-- this works.
    });

基本上由于某种原因，在 ProcedureCallBase 的上下文中，我无法创建type_tree对象，我也不知道为什么。

Dart版本:1.21.0-dev.11.2

Answer 1

可能是名称冲突。我已经看到分析仪不能在所有情况下都捕获到这些。