RAD Studio |  |

Avoiding Interdependencies

At all times when writing components, minimize the preconditions imposed on the developer. To the greatest extent possible, developers should be able to do anything they want to a component, whenever they want to do it. There will be times when you cannot accommodate that, but your goal should be to come as close as possible.

This list gives you an idea of the kinds of dependencies to avoid:

- Methods that the user must call to use the component
- Methods that must execute in a particular order
- Methods that put the component into a state or mode where certain events or methods could be invalid

The best way to handle these situations is to ensure that you provide ways out of them. For example, if calling a method puts your component into a state where calling another method might be invalid, then write that second method so that if an application calls it when the component is in a bad state, the method corrects the state before executing its main code. At a minimum, you should raise an exception in cases when a user calls a method that is invalid.

In other words, if you create a situation where parts of your code depend on each other, the burden should be on you to be sure that using the code in incorrect ways does not cause problems. A warning message, for example, is preferable to a system failure if the user does not accommodate your dependencies.

Copyright(C) 2009 Embarcadero Technologies, Inc. All Rights Reserved.
What do you think about this topic? Send feedback!