[webkit-dev] Bools are strictly worse than enums

[David Hyatt]

An example of nice boolean usage is:

paintTextWithShadows(context, font, textRun, 0, length, length, textOrigin, boxRect, textShadow, textStrokeWidth > 0, isHorizontal()); GOOD!

The last parameter is a boolean indicating whether or not the text run is vertical text or horizontal text.  It would be unreadable if you passed raw true or raw false to the function, but all the call sites pass isHorizontal(), so it's perfectly fine.

paintTextWithShadows(context, font, textRun, 0, length, length, textOrigin, boxRect, textShadow, textStrokeWidth > 0, true);  BAD!

dave
(hyatt at apple.com)

On Dec 3, 2010, at 4:30 PM, Darin Adler wrote:

> On Dec 3, 2010, at 1:37 PM, David Hyatt wrote:
> 
>> The only exception I would make to this rule is if all the call sites use variables and never pass in raw true or false. In that case there's no loss of readability, and whether you use an enum vs. a bool is irrelevant.
> 
> That’s right. There are cases where the boolean value passed in for a particular argument is typically the result of a boolean expression or boolean-returning function. We have definitely seen these in patch review.
> 
>> I think in general the rule should be "Keep your call sites readable, and convert to enums if you find that the call sites are becoming inscrutable."
> 
> Beyond the enum guidelines, it’s also true that functions with these boolean/enum arguments often indicate minor design mistakes. Many times we would be better off with multiple functions rather than a single function with an enum argument.
> 
>    -- Darin
> 
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