Ruby Tuesday: Debugging

When I was a freshman at Duke, coding away in Teer basement, I would often hear disgruntled engineers shout: “Damn, I’ve got 300 syntax errors, I left off the semicolon!  Why does everything have to be so exact?”  Those were the days of coding in C++, a language in which you had to actually compile, but hey it was faster than punchcards!

Nowadays we have dynamic typed languages like Ruby that don’t even require semicolons!  But that doesn’t mean we’re in the clear.  We still have to debug.  RoR has done a good job of building in a lot of debugging tools.

Here is my philosophy and methodology for debugging:

1. Errors and Exceptions are the easiest: Load the web app, if there is an error or exception thrown in the webpage tackle that first.  If I don’t know what the exception means e.g. InvalidAuthenticityToken, I will look it up.  And read about it and usually that will lead me to a solution.
2. I love logs! If the web app seems to load properly, but some functionality is broken I go look at the logs.  You can add log statements based on the level of logging you want to controllers in RoR with the following code: logger.debug “BUGGY” or logger.info “YO”
3. Data Corruption: to the Database! If the data appears to be displayed incorrectly then I go straight to the database.
4. Look & Feel: if something is off with the way the page is rendered then it is most likely something I did wrong in HTML or CSS.  I like using Firebug for CSS issues.
5. Vijayashanker Code If something is off about the functionality, and I have a sense of where it is happening I will go through and read my code.
6. Debugger Last: I’m not really a lazy person, but setting breakpoints and stepping through code can be tedious.  So I save this as a last resort if I can’t use any of the above techniques to find my bug.
7. I hate “debug” statements! I’m a neat freak, I don’t like polluting my code with debug statement, and creating more work for myself in having to go and remove them later.  If I can’t get the debugger to do what I want then I will resort to using debug statements.

As I was debugging today I discovered a few good resources here are a few of them:

• Debugging Rails Applications (walks you through common debugging techniques and also explains logging levels and configurations)
• Logging Tips (Everything you ever wanted to know relating to logging in RoR)
• RoR Google Group (I found solutions and insights into most of the problems I was experiencing today)

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