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How Do You Name Your Boolean Variables?

Jesse M. Holmes on March 15, 2019

I've seen some absolutely confounding names in recent code reviews. Sometimes you need to know if Godzilla exists! Do you: const godzillaExists;...

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Glenn Stovall • Mar 15 '19 • Edited

I prefer the first example in both cases. Specificity depends on the context. Does the function care about the "store" or not? Could Godzilla exist somewhere else, heaven forbid?

My go-to is to default to writing booleans in a way that makes them read more sentence-like in context. For example:

if ( godzillaExists && mothraExists ) {
  doBattle(godzilla, mothra) 
}

Dian Fay • Mar 15 '19

Hungarian notation is dead and good riddance to it, but formulating boolean names as isX or hasX does a lot for clarity.

Harvey Thompson • Mar 15 '19 • Edited

var hasGoodPoint = true;
var isMyConvention = true;

Also, I prefer not to pass booleans to (typically multi-argument) functions unless they are obviously expecting true or false (ie. property methods), so typically "can" or similar named functions:

This is okay:

canPost(true);

But this is not so good:

someMethod("Thing", true);

Some languages have named arguments, so in that case it'd be better to say:

someMethod("Thing", canDelegate=true);

Alternatively use enums:

someMethod("Thing", Delegation::Allowed);

Jonathan Kuhl • Mar 16 '19

usually something that makes grammatical sense paired with if

if(userExists && userHasValidCredentials) { handeLogin(user) }

I'm also not worried about long variable names because VSCode fills them in for me, and most editors do that for you.

aligear • Mar 18 '19

I usually use a variable with is as prefix, like

let isUserLogged = false;

MetaDave 🇪🇺 • Mar 15 '19

For Ruby, and the humble question mark.

def intersects_with?(other)
  return false if empty? || other.empty?

  (self & other).any?
end

How would you feel about godzilla?

satyanx1 • Mar 16 '19

At least they all follow camel casing

Alexander P. • Mar 15 '19

In that case I wouldn't use a boolean but an object. To check if it exists, I'd check if it's null or not.