Comments on: ruby notes 4a: overloading constructors http://malvasiabianca.org/archives/2006/12/ruby-notes-4a-overloading-constructors/ Tue, 22 May 2012 01:20:09 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: John Cowan http://malvasiabianca.org/archives/2006/12/ruby-notes-4a-overloading-constructors/comment-page-1/#comment-13547 John Cowan Tue, 02 Jan 2007 07:36:23 +0000 http://malvasiabianca.org/archives/2006/12/ruby-notes-4a-overloading-constructors/#comment-13547 It's pretty straightforward: when you call the new method on a Class object, it allocates space for the object using the primitive allocate instance method of Class, then invokes the initialize instance method on the new object, passing along the arguments of new. That method can and usually should invoke the initialize method of its superclass . If you want to override new, you can write your own new method, which may (for example) avoid calling superclass new when there is no need to actually construct a new object. It’s pretty straightforward: when you call the new method on a Class object, it allocates space for the object using the primitive allocate instance method of Class, then invokes the initialize instance method on the new object, passing along the arguments of new. That method can and usually should invoke the initialize method of its superclass .

If you want to override new, you can write your own new method, which may (for example) avoid calling superclass new when there is no need to actually construct a new object.

]]> By: david carlton http://malvasiabianca.org/archives/2006/12/ruby-notes-4a-overloading-constructors/comment-page-1/#comment-13238 david carlton Sun, 31 Dec 2006 22:59:10 +0000 http://malvasiabianca.org/archives/2006/12/ruby-notes-4a-overloading-constructors/#comment-13238 I'm thinking of getting rid of the public/private/protected notion for methods myself; I'm not sure what that's buying me any more. I confess I don't yet understand the details of the interactions between the class method <code>new</code> and the instance method <code>initialize</code> in Ruby, and in particular how to write replacements for the former. It seems like it should be straightforward, but there's one sentence in the relevant section of the book that's confusing me. I'll give it a try at some point... I’m thinking of getting rid of the public/private/protected notion for methods myself; I’m not sure what that’s buying me any more.

I confess I don’t yet understand the details of the interactions between the class method new and the instance method initialize in Ruby, and in particular how to write replacements for the former. It seems like it should be straightforward, but there’s one sentence in the relevant section of the book that’s confusing me. I’ll give it a try at some point…

]]> By: John Cowan http://malvasiabianca.org/archives/2006/12/ruby-notes-4a-overloading-constructors/comment-page-1/#comment-13220 John Cowan Sun, 31 Dec 2006 21:23:43 +0000 http://malvasiabianca.org/archives/2006/12/ruby-notes-4a-overloading-constructors/#comment-13220 In Smalltalk, where the public/private status of a method is a matter of convention (all methods are public, all instance variables are protected), the convention is that you never call the "initialize" method of a class unless you are a constructor (class method) of that class. Furthermore, if you always want your clients to invoke one or more specialized constructors, then you write a "new" class method that throws an error, and always use "super new" in your constructors. In Smalltalk, where the public/private status of a method is a matter of convention (all methods are public, all instance variables are protected), the convention is that you never call the “initialize” method of a class unless you are a constructor (class method) of that class. Furthermore, if you always want your clients to invoke one or more specialized constructors, then you write a “new” class method that throws an error, and always use “super new” in your constructors.

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