The document introduces Excellent, a static code analysis tool for Ruby on Rails that provides insights into potential issues rather than simply identifying errors. It includes various complexity measures and Rails-specific checks to enhance code quality. Users can execute analyses via Rake and generate HTML reports for further review.

1. Excellent

2. Me
Marco Otte-Witte
• Freelancer since 2007
• Web Development since ~1998
• PHP => (Java) => .NET => Ruby (on Rails)
• http://simplabs.com
• http://xing.com/profile/Marco_OtteWitte
• http://github.com/marcoow

3. Excellent
• static code analysis for Ruby
• like roodi, flog, reek etc. but more
• static code analysis for Rails
• (it‘s still beta despite the 1.5.4 - be kind)

4. Static Analysis
• it‘s not about finding errors
• it‘s no red/ green, no fail/ pass
• it‘s about getting hints on possible problems
• don‘t try to code for zero warnings!

5. Complexity Measures
global.checkEmail = function(e) {
function checkChars(s, i, l) {
while (i < l && "_-abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".indexOf(s.charAt(i)) != -1)
{
i = ++i;
} // end while
return (i);
}
function checkFirstLevelDomainChars(s, i, l)
{
while (i < l && "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".indexOf(s.charAt(j)) != -1)
{
i = ++i;
} // end while
return (i == l);
} // End of the function
var _loc1;
var j;
var _loc2 = e.length;
var _loc4 = false;
_loc1 = checkChars(e, 0, _loc2);
if (checkChars(e, 0, _loc2) == 0)
{
return (-1);
} // end if
j = _loc1;
while (_loc1 < _loc2 && e.charAt(_loc1) == ".")
{
...

6. Complexity Measures
• Cyclomatic Complexity
• ABC metric
• Flog
• also: method line count, even class name check
• etc.

7. Rails specific checks
• no restriction on (sometimes helpful, sometime not
so helpful) complexity measures etc.
• Rails checks can be red/ green
• no magic, finds stuff you forgot/ didn‘t know about
• AttrAccessibleCheck: specify attr_accessible!
• ValidationsCheck: validate!
• InstanceVarInPartialCheck: don‘t use instance vars
in partials!

8. Rails specific checks
1 class ShoppingBasket < ActiveRecord::Base
2
3 def initialize(items = [])
4 self.items = items
5 end
6
7 end

9. Rails specific checks
1 class ShoppingBasket < ActiveRecord::Base
2
3 def initialize(items = [])
4 self.items = items
5 end
6
7 end
$ excellent shopping_basket.rb
Excellent result:
test.rb
* Line 1: ShoppingBasket does not validate any attributes.
* Line 1: ShoppingBasket defines initialize method.
* Line 1: ShoppingBasket does not specify attr_accessible.
Found 3 warnings.

10. How does it work?
• ruby_parser
• sexp_processor
• Stack of context infos
• simple checks on these contexts

11. Run it via rake
1 require 'simplabs/excellent/rake'
2
3 desc 'Analyse the Excellent source with itself.'
4 Simplabs::Excellent::Rake::ExcellentTask.new(:excellent) do |t|
5 t.html = 'doc/excellent.html'
6 t.paths = ['lib']
7 end

12. with HTML reports

13. Get it
• http://simplabs.github.com/excellent/

14. Get it
• http://simplabs.github.com/excellent/
$ sudo gem install gemcutter
$ sudo gem tumble
$ sudo gem install excellent

15. Resources
• http://simplabs.github.com/excellent/
• http://wiki.github.com/simplabs/excellent
• http://static.simplabs.com/rails3-0-unstable.html
• http://parsetree.rubyforge.org/