Re: [Boost-Users] boost::shared_ptr and NULL

14 May 2002

      ...
From the book "Refactoring"
...
As an alternative, I usually find that the "Introduce Null Object" refactoring
  results in simpler and more readable code overall.  Perhaps not as concise
Sometimes you can simplify a conditional expression such as this:

  class Foo {
    void foo() {
      ...
    }
  };
  ...
  x = 0;
  ...
  if(x == 0) handleNullCondition();  //conditional expression
  else x->foo();

with something like this:

  class Foo {
    void foo() {
      ...
    }
  };
  class NullFoo {
    void foo() {
       handleNullCondition();
    }
  };
  ...
  x = new NullFoo(); //instead of x = 0
  ...
  x->foo(); //conditional expression goes away
            //polymorphism handles it instead

So if I only have one check for class Foo being null, the code becomes bigger (I create a new class).  But if I had many checks all over the place, it actually simplifies the code (a lot of if statements go away).
  ----- Original Message ----- 
  From: Andrew R. Thomas-Cramer 
  To: Boost-Users@yahoogroups.com 
  Sent: Tuesday, May 14, 2002 7:11 AM
  Subject: Re: [Boost-Users] boost::shared_ptr and NULL

  ----- Original Message -----
  From: "Sean Shubin" <sshubin@socal.rr.com>
  To: <Boost-Users@yahoogroups.com>
  Sent: Tuesday, May 14, 2002 3:25 AM
  Subject: Re: [Boost-Users] boost::shared_ptr and NULL

  though.

  I'm not familiar with that term. Could you define it and provide an example?

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