Hi all,
our coding standards [1] include include a ban on break, continue, and
multiple return statements. These restrictions originate from Dijkstra's
rules for structured programming [2], which ensure a linear program flow
and help to keep long procedures comprehensible.
Programming has changed since then and I think the code we write today
(object-oriented, short methods) does not really benefit from these rules
anymore. In fact, using breaks or multiple returns often results in code
that is clearer and easier to read. For example, take the following method:
String findFirstMatch( List<String> strings ) {
for( string : strings ) {
if( string.startsWith( "/" ) ) {
return string;
}
}
return null;
}
Following our conventions, we used to write it like this:
String findFirstMatch( List<String> strings ) {
String result = null;
Iterator<String> iterator = strings.iterator();
while( iterator.hasNext() && result == null ) {
String string = iterator.next();
if( string.startsWith( "/" ) ) {
result = string;
}
}
return result;
}
The second version is not only longer, I think that the extra code to avoid
the return even obscures its mechanics. It's easy to miss the "&& result ==
null" in the while condition which actually makes the difference between
finding the first or the last match.
I think that clarity and readability should be the guiding principle for
writing code, especially for framework code that is read much more often
than it is written. So I have broken with these rules, first as an
experiment, but meanwhile I'm convinced that they are not beneficial
anymore.
I'm not saying that breaks and multiple returns should be generally
preferred, but neither should they be generally avoided. Some code is
better written with a break and I don't believe that avoiding these
statements makes our code clearer or safer.
I therefore propose to lift the ban on break, continue and multiple return
statements, and at the same time to reinforce our commitment to writing
short and concise methods in an additional paragraph in our coding
standards.
What do you think?
Regards,
Ralf
[1] http://wiki.eclipse.org/RAP/CodingStandards
[2] http://en.wikipedia.org/wiki/Structured_programming
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