Comments on: Procedural Language Eliminated GOTOs; OO Eliminated IFs

By: How to think about OO : Clevertester

How to think about OO : Clevertester — Mon, 07 Jun 2010 19:52:37 +0000

[...] Now that we took advantage of polymorphism, each different kind of user knows how to log in and we can easily add new kind of user type to the system. Also notice how the user no longer has all of the flag fields which were controlling the ifs to give the user different behavior. The ifs and flags have disappeared. [...]

By: Berlin Brown

Berlin Brown — Wed, 25 Nov 2009 16:32:34 +0000

He is insane? Remove logic?

I like it.

By: How to leave a comment

How to leave a comment — Wed, 29 Apr 2009 05:57:49 +0000

private Getter getter = new Getter() {
public T get() {
final T value = initialize();
getter = new Getter(){
T get() { return value; }
}
}
};

By: Christian Gruber

Christian Gruber — Thu, 06 Nov 2008 04:35:29 +0000

I’m really starting to like Scala, since it runs in the JVM, but allows me to pass functions similar to your javascript example.

As to the ifs, ifs aren’t per-se bad, but they are harder to test, since you have to test each possible boolean outcome, and in complicated if/elseif/elseif/else constructs, you are often having to stage a lot of tests. If you could separate the flow/decision logic from the processing logic (the stuff done in each test), you can abstract and make the flow logic generic and test is separately from the work itself.

By: John M. Długosz

John M. Długosz — Mon, 20 Oct 2008 16:27:21 +0000

Your assertion of “You can’t remove these IFs” is language centric. Polymorphism and overloading in Java replaces explicit comparisons against types, and only types. Furthermore, virtual function calling distinguishes polymorphic types at run-time, and signature overloading does so with declared types at compile time.

Other languages don’t necessarily have these specific features or these limitations. In functional languages, you can typically “overload” values so you could write a factorial function as two forms: one for the base case and one for the recursive case. Something like

fact[1] := 1
fact[n] := n×fact[n-1]

To be more concrete, in Perl 6 you could write:

multi sub fact (Int $n)
{ return $n * fact($n – 1); }
multi sub fact (Int $n where 1)
{ return 1; }

and then you can check for improper arguments as well, by adding another form:

multi sub fact (Int $n where { $_ < 1 })
{ fail; }

As for your specific example, how is what you describe different from simply using a ‘final’ variable directly (I assume this is like ’static’ in C++’) which implements the specific feature of “initialize on first use”? I don’t know the meaning of the Java syntax

new Getter() { class-like-block }

which is key to your idiom.

By: john smith

john smith — Fri, 15 Aug 2008 12:35:09 +0000

I don’t understand. When did anyone say IFs were bad? I cannot see at all how all that code is better than an IF statement.

You want to add all kinds of gunk to the Java language to avoid IFs? No one has ever shown me that adding closures in Java will allow it to do something it doesn’t do now. Just because it saves a couple of lines of code doesn’t mean the language should be changed. In this case, it adds lines to code.