Wednesday, July 21, 2010

Software Principles are like some Life Principles

Software principles are useful tools for design and implementation and they help us produce quality products. However, software principles can be compromised at times. They don't always have to be followed as there are exceptions to the rule. In some ways, they are similar to some life principles, and this blog explores that idea.

Software and Life

In life we have ethics and morals that we live by. Ethics and morals manifest themselves as life principles. They give us a framework to become better people, respect one another, and ultimately improve our quality of life.

In the software industry we have software design principles.  They are rules we operate under in order to make the products we develop elegant, easy to understand, and maintainable.  Software products run our economy or make our day to day lives easier, and software principles play a large role in allowing that to happen.

However, software design principles are not meant to be dogmatic. They are not meant to be strictly adhered to.  The use of software principles should be evaluated within the prism of trade offs.  Software principles are essentially rules of thumbs and can be broken if it's the most pragmatic thing to do.

Software principles are like some life principles . . . but unlike others.  To illustrate my point, let's consider some life principles that can be considered absolute, i.e, should never be broken no matter what the circumstances.

Don't Cheat, and Be Nice

Take the rule "Don't cheat." Under no circumstances would I teach my son that it is permissible to cheat.  It's not OK to cheat on a test at school. It's not OK to cheat on your taxes, and its not OK to cheat on a board game at home.  No matter what the context, big or small, cheating is not beneficial. It only hurts others and ultimately your self.  Software principles aren't like the cheating principle. 

Another example would be "Never treat a person as a means to an end." It is unethical to use a person strictly as a means to an end with disregard to their humanity.  People should be treated as human beings, not as objects. Under no circumstances, would I teach my child to "use" someone just for the sake of personal gain and devoid of respect.  Software principles aren't like ethical principles . . . we can break them if needed.

So what are software principles like then, and what software principles am I talking about?  Most life principles we live by are general rules of thumb, they are not absolutes. Software principles are like that. Here are a few examples of what I mean:


We live by the principle of "Always tell the truth", but this rule doesn't always apply.  Take for example white lies. If your wife asks you, "Do I look fat in this dress?", you would be asinine to say yes.  Most us would say "No honey, you look great!" Even though your beautiful wife may be slightly overweight (no big deal in my eyes, personally.) 

In software, we have the DRY principle: Don't Repeat Yourself. This should be something you mostly do and can greatly contribute to clean code.  But would you really want to create a full fledged Template or Strategy Method Pattern to save 1 or 2 lines of code?  Sometimes violating the DRY principle can avoid excessive pattern usage, which can cripple a project and make code unintelligible. Evaluate the trade offs for DRY and make the best decision.

Law Of Demeter

How about the life principle of "Always eat healthy"?  Yes, we should eat healthy and watch our diet, in general, so we can live a quality life. But we are allowed to break the rule on holidays and eat the fried turkey and pecan pie. It is permissible to go out with the guys and down some beers and wings once in a while. It's not going to kill you.  If eating unhealthy is the exception, it is fine.

The Law of Demeter is a software principle that enables loose coupling and limits the knowledge of one component to another.  Following this rule keeps your code understandable and limits dependencies. But even though its called a "law", it should be viewed more as a guideline.  If you are dealing with an anemic object, and just need to get some data, it is permissible to for a client to dig through objects to get what it needs.  The alternative would be to blow up the API with several needless methods, which is a documented disadvantage of Law of Demeter.


When designing software, we should understand that software principles should be followed in order to produce quality code. However, use them in a pragmatic manner and don't pursue a software principle so hard that it makes your life and code, miserable.  Evaluate your design in terms of trade offs. After all, we certainly have life principles that we don't always follow, and software principles are the same way. Do what's best for value added effort and leave the dogma behind.

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