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    <p>[Note: I am not recommending that you do this.] There's a fair chance you can accomplish what you want. The cast to this.type is a lie, but the JVM doesn't know that and can't throw an exception because the singleton type is a scala concept.</p> <p>Now if you're actually using the singleton property of this.type anywhere, this will get you in trouble in a hurry. But if all you want to do is get covariant return types without all the trouble of typing them, with only the small downside of the huge ugly cast all over the place:</p> <pre><code>trait Expression { def left : Expression def right : Expression def new_with_changes(l : Expression, r : Expression) : this.type } case class Derived1(left : Expression, right : Expression) extends Expression { def new_with_changes(l : Expression, r : Expression) = Derived1(left, right).asInstanceOf[this.type] def foo() = "Derived1" } case class Derived2(left : Expression, right : Expression) extends Expression { def new_with_changes(l : Expression, r : Expression) = Derived2(left, right).asInstanceOf[this.type] def bar() = "Derived2" } </code></pre> <p>And in action:</p> <pre><code>scala&gt; Derived1(Derived1(null,null), null) res0: Derived1 = Derived1(Derived1(null,null),null) scala&gt; res0.new_with_changes(res0, null).bar &lt;console&gt;:6: error: value bar is not a member of Derived1 res0.new_with_changes(res0, null).bar ^ scala&gt; res0.new_with_changes(res0, null).foo res2: java.lang.String = Derived1 scala&gt; Derived2(Derived2(null, null), null) res3: Derived2 = Derived2(Derived2(null,null),null) scala&gt; res3.new_with_changes(null, res3).foo &lt;console&gt;:6: error: value foo is not a member of Derived2 res3.new_with_changes(null, res3).foo ^ scala&gt; res3.new_with_changes(null, res3).bar res6: java.lang.String = Derived2 </code></pre>
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    1. POWhy cannot this.type be used for new instances
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    1. COHacky, but it works. If we could get something like this into the language, that would be cool.
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Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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