codeql/python/ql/src/Metrics/NumberOfStatements.qhelp

<!DOCTYPE qhelp PUBLIC
  "-//Semmle//qhelp//EN"
  "qhelp.dtd">
<qhelp>
<overview>
<p>
This metric measures the number of statements that occur in a module.
</p>

<p>
If there are too many statements in a module, it is generally
for one of two reasons:
</p>

<ul>
<li>
One or more individual classes or functions of the module contain too many statements,
making them hard to understand, difficult to check and a common source of defects
(particularly towards the end of the class or function, since few people ever read that
far). These entities typically lack cohesion because they are trying to do too many things.
</li>

<li>
The module contains too many functions or classes, which generally indicates that it is
trying to do too much, either at the interface or implementation level or
both. It can be difficult for readers to understand because there is a
confusing list of operations.
</li>
</ul>

</overview>
<recommendation>

<p>
As described above, modules reported as violations by this rule contain one
or more classes or functions with too many statements, or the module itself contains
too many classes or functions. </p>

<ul>
<li>
Individual classes or functions of the module that contain too many statements
should be refactored into multiple, smaller parts. As a rough
guide, functions should be able to fit on a single screen or side of A4. Anything
longer than that increases the risk of introducing new defects during routine code changes.
</li>

<li>
Modules that contain too many functions or classes often lack cohesion and are
prime candidates for refactoring.
</li>
</ul>


</recommendation>
<references>


<li>
M. Fowler. <em>Refactoring</em>. Addison-Wesley, 1999.
</li>



</references>
</qhelp>