Avalon Project - Coding Standards

Coding Standards

This document describes a list of coding conventions that are required for code submissions to the project. By default, the coding conventions for most Open Source Projects should follow the existing coding conventions in the code that you are working on. For example, if the bracket is on the same line as the if statement, then you should write all your code to have that convention.

If you commit code that does not follow these conventions and you are caught, you are responsible for also fixing your own code.

Brackets should begin and end on a new line. Examples:


if( foo )
{
    // code here
}    

try
{
    // code here
}
catch( final Exception bar )
{
    // code here
}
finally
{
    // code here
}    

while( true )
{
    // code here
}

The preference is to include extra spaces between parenthesis and expression. For example;
if( foo )
4 spaces. NO tabs. Period. We understand that a lot of you like to use tabs, but the fact of the matter is that in a distributed development environment, when the cvs commit messages get sent to a mailing list, they are almost impossible to read if you use tabs.

In Emacs-speak, this translates to the following command: (setq-default tab-width 4 indent-tabs-mode nil)

In vim, having the following in your .vimrc will help:
set tabstop=4 set expandtab set list set listchars=tab:>.
Unix linefeeds for all .java source code files. Other platform specific files should have the platform specific linefeeds.
Javadoc SHOULD exist on all your methods. Also, if you are working on existing code and there currently isn't a javadoc for that method/class/variable or whatever, then you should contribute and add it. This will improve the project as a whole.
The Jakarta Apache/Avalon License MUST be placed at the top of each and every file.
If you contribute to a file (code or documentation), add yourself to the top of the file. For java files the preferred Javadoc format is:
@author <a href="mailto:user@domain.com">John Doe</a>
Indent comments on an 80 column basis and the code on a 100 column, using a two more indents when a line must be wrapped.
We focus on readability over performance, at least initially. Source code optimization is the last thing to be done to increase performance. If the code is not performing then it is better to re-engineer it rather than to expand loops, take out variable declarations etc. When the code is stable and has a well defined purpose and interface it may be appropriate to do source code optimization.
Try to javadoc all methods and variables, especially public, protected and default access methods and member variables. Also add code comments when you think it's necessary (like assumptions).

Variables are declared in the inner scope.

while( myListIterator.hasNext() ) 
{
    final String myString = (String)myListIterator.next();
}

Variable should be descriptive and ideally English words. The exceptions being; loop counters (usually use i, j and k), exceptions (use concatenation of word separating characters - ie SocketException is abbreviated as se) and other commonly used abbreviations (ie sb for StringBuffer).

try 
{
    for( int i = 0; i < 10; i++ )
    {
        // some stuff
    }
} 
catch( final FileNotFoundException fnfe )
{
    // some stuff
}
catch( final IndexOutOfBoundsException ioobe ) 
{
    // some stuff
}

Use String concatenation except in extremely performance sensitive sections. This leaves StringBuffer optimization to the compiler. So use:
final String myString = "test " + "for " + "performances";
Try not to declare a method as 'synchronized'. If a method accesses a shared resource then surround accesses to that resource with a synchronized block. Ideally the synchronized block should surround the smallest possible area. For example:
public void sharedMethod() { String display = null; synchronized( this ) { display = mySharedObject.getHelloWorld(); } System.out.println( display ); }
If you are within a static method, then you may have to create a static object whose sole purpose in life is to provide the lock you need. Alternatively you could use the Class object for the class you are in. That is, if you're in class MyClass, use "MyClass.class".
Have the names of all member instance fields start with the prefix "m_". Example:
class MyClass { Class m_class = MyClass.class; int m_users; }

Thanks for your cooperation.

-The Avalon Team