bliki tagged by: language feature
Object-oriented languages divide a program into modules called classes. Each class contains features, which consist of data (fields) and methods. (Not all languages use these terms, but they'll do for this.) Languages have various rules about what other classes can access the features of a class, these are often based on access modifiers that apply to a class.
13 May 2003
Call Super is a minor smell (or anti-pattern if you like) that crops up from time to time in OO frameworks. Its symptoms are pretty easy to spot. You are inheriting from a super-class in order to plug into some framework. The documentation says something like "to do your own thing, just subclass the process method. However it's important to remember to start your method with a call to the super-class". An example might be something like this.
11 August 2005
As there is a growing interest in dynamic languages, more people are running into a programming concept called Closures or Blocks. People from a C/C++/Java/C# language background don't have closures and as a result aren't sure what they are. Here's a brief explanation, those who have done a decent amount of programming in languages that have them won't find this interesting.
8 September 2004
I've long been loath to write any contributions on the debate between static and dynamic typing in programming languages. This is one of those emotive topics where people seem driven to debate rather than listen. But since I've been asked a few times about it, I will contribute my personal experiences. I'm not trying to convince anyone of anything, but I hope someone finds some food for thought in them.
14 March 2005
Is it good OO design to have data in my classes with the protected AccessModifier?
14 May 2003
Published Interface is a term I used (first in Refactoring) to refer to a class interface that's used outside the code base that it's defined in. As such it means more than public in Java and indeed even more than a non-internal public in C#. I've argued that the distinction between published and public is actually more important than that between public and private.
26 December 2003
From time to time I run into people who want to get a smalltalk and give it a spin to see what the fuss is about. My old favorite introductory smalltalk book went out of print, but I just discovered you can now download it from here together with lots of other smalltalk related material. The material is hosted by Stéphane Ducasse, who was a co-author on an excellent book on reengineering patterns.
26 October 2005
All services offered by a module should be available through a uniform notation, which does not betray whether they are implemented through storage or through computation.
-- Bertrand Meyer
Bertrand Meyer coined this principle in his highly-influential book Object-Oriented Software Construction.
The essential point of the principle is that if you have a person object and you ask it for its age, you should use the same notation whether the age is a stored field of the object or a computed value. It effectively means that a client of the person should neither know nor care whether the age is stored or computed.
20 April 2011
An annotation on a program element (commonly a class, method, or field) is a piece of meta-data added to that program element which can be used to embellish that element with extra code.
When you learn about objects, you usually learn that they can capture two kinds of data: instance and class. Instance variables are the most common case, the data varies with each instance of the object. Class variables, often referred to as static variables, are shared across all instances of a class. Every instance points to same value and any changes are seen by all. Class variables are much less common than instance variables, especially mutable class variables.
9 January 2007
When I first started programming in Smalltalk one of the things I liked right from the start were the collection classes. They allowed you to simply do a bunch of common and powerful operations on collection classes. When Java appeared, I missed these kinds of methods - the Java (and C#) collections were very limited compared to Smalltalk. The main reason for this limitation is that Java doesn't have any convenient implementation for a Closure. The powerful Smalltalk methods for collections all relied on closures.
1 August 2005
If I want to teach people object-orientation, which language should I use?
23 May 2003
When I first came across C# I liked the notion of properties
right from the start. The getX and setX conventions of C++/Java always
seems rather silly to me, it's much more natural to write
= other.X. Providing a property with get and set methods turns
a common convention into a naturally supported feature of the
4 February 2004
One of Ruby's most popular features is its support for metaprogramming, that is features that act like they change the language itself - introducing things like new keywords.
26 October 2006
A common phrase that's bandied about when talking about DomainSpecificLanguages (or indeed any computer language) is that of noisy syntax. People may say that Ruby is less noisy than Java, or that external DSLs are less noisy than internal DSLs. By Syntactic Noise, what people mean is extraneous characters that aren't part of what we really need to say, but are there to satisfy the language definition. Noise characters are bad because they obscure the meaning of our program, forcing us to puzzle out what it's doing.
9 June 2008