From: Lorenzo Jorquera <lorenzo_jorquera@...>
Date: 2005-04-29T05:31:13+09:00
Subject: Re: Comments Are More Important Than Code

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Really sorry for the mangled quotes

I meant

Eric Schwartz wrote: 
"Dave Fayram" writes:
> I'd much prefer to see (this is pseudo and formatted for short lines,
> so bear with me):
>
> def my_appropriately_named_test
> long_name = "This name is far too long."
> assert_raise Module::InputValidationError,
> @inst.the_func( long_name )
> end
>
> Then I can test it. If I ever make a change and accidently invalidate
> it, then I'll know. If we ever eliminate that restriction, the test
> will break and we'll know to update it.

>How will you know if it's the test or the code that's broken? Without
>comments in the_func telling you why that exception is raised, you
>could end up fixing the wrong problem.

When you run your unit tests very often (tipically several times an hour) you will know exactly why the test failed.

>A not-uncommon case is that you have to call into a 3rd-party C or C++
>library (the infamous Jukebox example in Pickaxe 1, for instance), and
>that library enforces some restrictions that aren't necessarily
>obvious. Let's say we have implemented the infamous Jukebox
>application only supporting ASCII song titles, and we now want to add
>support for UTF-8. Since it's been some time, and the original coder
>has moved on to another company, we've forgotten that libjukebox
>doesn't work with, say, UTF-8.

>If I had a comment in the_func saying:

>/* libjukebox can't handle songs with UTF-8 encoded titles */
>raise Module::InputValidationError if has_utf8?(title)

>That helps me a lot more than just:

>raise Module::InputValidationError if has_utf8?(title)

>In the latter case, I might just think, "Okay, they didn't want to
>support UTF-8 in revision 1, so now i can take it out." In the former
>case, I know *why* they didn't support it, and it wasn't because they
>were lazy, or pressed for time. So instead of removing the code, and
>its associated test, I know to ask Jukebox, Inc. for a new library
>that does support UTF-8.

In this case, I would prefer a more especific exception: 

raise Module::LibjukeboxCantHandleUTF8 if has_utf8?(title) 

Lorenzo.





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