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Re: How to write constructor for an abstarct class?

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On 12/28/2015 4:47 PM, j4n bur53 wrote:
> There are a couple of reasons for abstract classes.
>
> 1) There is a certain design school which says base
>     classes should be always abstract, only non-base
>     classes should not be abstract.

>     The design rule is often broken,

It is one of those "90% rules" that one should
follow when not thinking about it but be ready to
skip after having thought about it.

The general rule is: only extend classes that has
been written to be extended.

That is obviously the case for abstract classes.

For a concrete class one has to be careful - some
classes has been written to be extended but a lot has not.

Joshua Bloch has some examples in hos Effective Java book
about how bad it can turn out when trying to extend
concrete classes in java.util.

Arne

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Thread

How to write constructor for an abstarct class? Xue Feng <xf.lotus@yahoo.com> - 2015-12-28 20:44 +0800
  Re: How to write constructor for an abstarct class? Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-12-28 08:21 -0500
    Re: How to write constructor for an abstarct class? Jan Burse <janburse@fastmail.fm> - 2015-12-28 19:20 +0100
      Re: How to write constructor for an abstarct class? Jan Burse <janburse@fastmail.fm> - 2015-12-28 19:25 +0100
        Re: How to write constructor for an abstarct class? Jan Burse <janburse@fastmail.fm> - 2015-12-28 19:28 +0100
          Re: How to write constructor for an abstarct class? Lew <lewbloch@gmail.com> - 2015-12-28 10:40 -0800
          Re: How to write constructor for an abstarct class? Eric Douglas <e.d.programmer@gmail.com> - 2015-12-28 10:42 -0800
            Re: How to write constructor for an abstarct class? Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-12-28 14:29 -0500
            Re: How to write constructor for an abstarct class? j4n bur53 <janburse@fastmail.fm> - 2015-12-28 22:26 +0100
              Re: How to write constructor for an abstarct class? Eric Douglas <e.d.programmer@gmail.com> - 2015-12-28 13:37 -0800
              Re: How to write constructor for an abstarct class? j4n bur53 <janburse@fastmail.fm> - 2015-12-28 22:47 +0100
                Re: How to write constructor for an abstarct class? Eric Douglas <e.d.programmer@gmail.com> - 2015-12-28 13:58 -0800
                Re: How to write constructor for an abstarct class? j4n bur53 <janburse@fastmail.fm> - 2015-12-28 23:06 +0100
                Re: How to write constructor for an abstarct class? Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-12-28 17:43 -0500
                Re: How to write constructor for an abstarct class? Lew <lewbloch@gmail.com> - 2015-12-28 15:14 -0800
                Re: How to write constructor for an abstarct class? j4n bur53 <janburse@fastmail.fm> - 2015-12-29 15:02 +0100
                Re: How to write constructor for an abstarct class? Arne Vajhøj <arne@vajhoej.dk> - 2015-12-29 15:37 -0500
                Re: How to write constructor for an abstarct class? Arne Vajhøj <arne@vajhoej.dk> - 2015-12-29 15:28 -0500
            Re: How to write constructor for an abstarct class? Arne Vajhøj <arne@vajhoej.dk> - 2015-12-29 15:21 -0500
              Re: How to write constructor for an abstarct class? Arne Vajhøj <arne@vajhoej.dk> - 2015-12-29 15:22 -0500
  Re: How to write constructor for an abstarct class? j4n bur53 <janburse@fastmail.fm> - 2015-12-29 16:24 +0100

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