Pattern

Subclass has no constructor

class Sample: Base()

1	class Sample: Base()

Add bracket and argument after the base class.

Subclass has only primary constructor

class Sample(): Base()

1	class Sample(): Base()

Subclass has only secondary constructor

class Sample: Base { constructor(): super() { } }

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class Sample: Base {   constructor(): super() { } }

Don’t write bracket or argument after base class, and secondary constructor must delegate to constructor of the base class.

Subclass has primary and secondary constructors

class Sample(): Base() { constructor(x: Int): this() { } }

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class Sample(): Base() {   constructor(x: Int): this() { } }

Subclass secondary constructor must delegate its constructor.

Un-inheritable class

If base class primary constructor is private and it has no secondary constructor, then it is not inheritable. (I haven’t found the way to inherit yet.)