base call

Question

3.00/5 (1 vote)

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C#

public Connector(IShape source,IShape desti, double cost, IShape sourceentrance, IShape destientrance) : base(source.Center, desti.Center)
{
  this._cost = cost;
  this._source = source;
  this._desti = desti;
  this._entrancesourceID = sourceentrance;
  this._entrancedestiID = destientrance;
}

Class name is Connector and this is a constructor call
I want to do to this:

C#

if(source == null)
  base(sourceentrance.Centre, desti.Centre)
else 
  base(source.Centre, desti.Centre)

How can I do this?

Posted 15-Dec-10 20:15pm

hotthoughtguy

Updated 16-Dec-10 4:20am

Toli Cuturicu

v4

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OriginalGriff · Accepted Answer · 2010-12-15T21:33:00

You cannot do that.

The Base class constructor has to be called before the execution of any derived class constructor code - otherwise classes derived from a base class could not rely on or use any of the base class elements.

As a result, you can only access the base constructor from the definition of your class, by providing a fixed construtor reference using a colon and the base keyword.

To do what you want, you will have to extract the code from the base constructor into a public/protected method and access that from your derived constructor.

tolw · Accepted Answer · 2010-12-15T21:51:00

Solution 2

The simplest way is to change the base class constructor to take three parameters and make it decide what to do. The call would be:

base(source, sourceentrance, desti)

If you don't want to change anything you could try:

base( (source != NULL) ? source.Centre : sourceentrance.Centre, desti.Centre)

Posted 15-Dec-10 21:51pm

tolw

Updated 15-Dec-10 21:53pm

v2