Measuring your code

@nateabele

nate.abele@gmail.com

A talk by Nate Abele

Confession

Coercion, red bars & broken windows

Continuous

Goal: Perfection

Or at the least, continuous improvement

a.k.a. 改善 (kaizen)

What people usually think

Estimating costs

Projecting deadlines

Managerial BS!

Client Spec SheetFlash intro with no load time

User account logins, password optional

Ajax chat

“Like Google”

(actual bullet points, some paraphrased)

...and my personal favorite

Social network

Measurement is an essential element of management; there is little chance of controlling what we can not measure.

- Wikipedia, “Software metric”

Wherefore... (WTF) ?

“Engineer” & “architect”

Cognitive DissonanceEngineers deal with tangible, immutable constraints, like gravity

The practice of developing software is an inherently creative discipline

*

* Thank you, Jones

Cognitive DissonanceDeveloper constraints (scope, schedule, budget) potentially often in flux

Software is inter-related; working on one part changes the others

No project is exactly the same as another

/

ConclusionIt’s not useful to measure high-level, intangible things like whole projects

This is where scrum comes in handy

Instead, we can use lower-level, more concrete measurements

What can we measure?

Code!!

More specifically...Unit test coverage

Complexity

Speed

Documentation

More specifically...

Standards conformance

Refactoration!

Backing up...What is a metric?

You can cheat and use booleans, too

Measurement assigns numbers based on well-defined meaning

- Sometimes the environment must be modified

- Special development procedures that track various activities - Wikipedia (paraphrased)

Notes on continuous integrationA build system

Runs on every code commit

Runs tests

Reports

Metric examples

PHP Code Sniffer

PEAR Package:http://pear.php.net/package/PHP_CodeSniffer

Checks conformance of a set of files against a series of classes called “sniffs”

PHP Code Sniffer

$ phpcs /path/to/code/myfile.php

FILE: /path/to/code/myfile.php------------------------------------------------------------------------FOUND 5 ERROR(S) AFFECTING 2 LINE(S)------------------------------------------------------------------------  2 | ERROR | Missing file doc comment 47 | ERROR | Line not indented correctly; expected 4 spaces but found 1 51 | ERROR | Missing function doc comment 88 | ERROR | Line not indented correctly; expected 9 spaces but found 6------------------------------------------------------------------------

PHP Code Sniffer

$ svn commit -m "Test" temp.phpSending        temp.phpTransmitting file data .svn: Commit failed (details follow):svn: 'pre-commit' hook failed with error output:

FILE: temp.php--------------------------------------------------------------FOUND 1 ERROR(S) AND 0 WARNING(S) AFFECTING 1 LINE(S)-------------------------------------------------------------- 2 | ERROR | Missing file doc comment--------------------------------------------------------------

This is important because things are standardized

Measuring code complexityCyclomatic complexity

Directly measures the number of linearly independent paths through a program's source code.a.k.a. 1 + the number of times it branches

Measuring code complexity

Measuring code coverage

Measuring documentation coverageCheck it out @ http://thechaw.com/api_generator

Measuring documentation coverageCheck it out:http://thechaw.com/api_generator

A series of rules

Assigns weights based on docblock content and various docblock tags

Measuring documentation coverageBasic checks:

Do doc tags exist?Incomplete @param tags?Do @param tags match actual params?Does it have a @link to the man page?

Profiling

ProfilingGet timing / memory usage on every test run

Granular, get statistics per test method

Using continuous integration, code is profiled on each commit, all on a granular level

Case study

CakePHP 1.2 release cycle

1.2 alpha 1.2 beta 1.2 RC1 1.2 RC2 1.2 RC3 1.2 RC4

Metrics are your canary in the coal mine of your development cycle

By tracking profiler stats (and other metrics), we can see trends over time, and catch problems before they become problems

Plus, who doesn’t like pretty graphs?

Finding things to measure

CakePHP Inspector classCakePHP Parser classBased on the awesome work of Sean Coateshttp://github.com/scoates/tokalizer

Finding things to measure

Finding things to measure

Finding things to measure

Finding things to measure

Finding things to measure

In a dynamic language like PHP, this is a hard problem.

However, deep code introspection allows us to ask & answer some very interesting questions

Project mess detection in PHPUnit

Beyond copy-paste detection & into pattern recognition

High-level refactoring tools

Can “good code” be quantified??

Goodvs.

good enoughvs.

the economy