Accumulative Construction

re: Accumulative Construction

PeterRitchie — Thu, 23 Apr 2009 16:09:48 GMT

@Charles. Also, multiple initialization is an oxymoron; it makes the interface and the resulting code confusing.

re: Accumulative Construction

PeterRitchie — Thu, 23 Apr 2009 16:08:32 GMT

@Charles. It looks like you're trying to reuse object instances. I don't recommend that because now the type must support reuse in that way. Unless Initialize can guarantee that the state is complete reset upon every call (and it can't) your implementation of Person is dependent on it's usage. This limits reuse and makes for a tightly coupled design.

Instance re-use like this is a premature optimization. The GC will do much of that for you, making any perceived savings negligible at the expense of readability and maintainability.

re: Accumulative Construction

Charles Rex — Thu, 23 Apr 2009 14:29:37 GMT

Hello

When I have asked about initialization,

I was thinking to do something useful afterwards:

Thus, it makes sense to "initialize" several times.

Person p = new Person("f","m","l",4);

p.Initialize("f1","m1","n1",11);

p.DoSomething();

p.Initialize("f2","m2","n2",22);

p.DoSomething();

p.Initialize("f3","m3","n3",33);

p.DoSomething();

etc

Many thanks.

re: Accumulative Construction

PeterRitchie — Thu, 23 Apr 2009 14:29:08 GMT

@Peter. It depends on the type. Domain Model types aren't necessarily going to have a property setter for each and every attribute of the type. The recommended practice is to model behaviour with Domain Model types; they aren't data containers. In cases like this, object initializers can't be used.

Also, types used in multithreaded environments will tend to be immutable; meaning their value can't change after construction. In cases like this object initializers can't be used either.

re: Accumulative Construction

Petar Repac — Thu, 23 Apr 2009 13:20:58 GMT

With object initializers in C# 3.0 I think many of old constructors can/should be removed.

Only constructors that demand essential information for object construction should exist.

re: Accumulative Construction

PeterRitchie — Thu, 23 Apr 2009 12:30:46 GMT

@Charles. I disagree. "Construction" is tantamount to "initialization". In your example, it doesn't make sense to "initialize" several times.

In object-oriented design we want to model the behaviour of real-world object through the design of our classes. With a person type I would have specific methods that model the behaviour of a person. A person never "Initializes" itself. It may:

public ChangeName(IEnumerable<String> givenNames, String surname)

{

/.../

}

public Age(int yearsToAddToAge)

{

//...

}

You wouldn't arbitrarily re-initialize a person in response to some action. Given names and age properties of a person, you're either going to change the name of a person or age them. Having ChangeName and Age behaviour makes it explicit how to use Person and as a result makes it explicit what you are doing to a Person object.

re: Accumulative Construction

Charles Rex — Thu, 23 Apr 2009 12:03:35 GMT

Hello,

- Once a Person object is created, I feel there's a need for a method like this:

Initialize(firstName, middleName, lastName, aAge)

Person p = new Person("f","m","l",4);

p.Initialize("f1","m1","n1",11);

p.Initialize("f2","m2","n2",22);

p.Initialize("f3","m3","n3",33);

//etc

How would you write the Initialize method in order to avoid copy paste from the

constructors ??

public Initialize( String firstName, String middleName, String lastName, int age)

{

//assignments

this.firstName = firstName;

this.middleName = middleName;

this.lastName = lastName;

this.age = age;

}

If I do this, all the benefit of having the initialization code in one place, vanishes.