Counts the number of parameters of a callable (a method or a constructor).

It is generally considered bad practice to have methods with 8 or more parameters: in those cases, it is often preferable to encapsulate the tuple of parameters in a new class.

Pre-packaged Query

Query name = "Semmle/Metrics/Methods/Many-parameter methods"

Reports methods that have more than seven parameters, in the Eclipse problems view.

from MetricCallable c, int n
where c.fromSource() 
      and 
      n=c.getNumberOfParameters()
      and
      n > 7
select c, "too many parameters"

.QL Source of Metric

This metric is defined in the class MetricCallable:

   int getNumberOfParameters() {
      result =  count(int pos | params(_,_,_,pos,this,_) ) 
   }

References

Martin Fowler. Introduce Parameter Object Refactoring .

Streek. Bad Smells in Code: Long Parameter List , University of California at Berkeley, 2006.