[Zope] dtml-if and checkboxes

[Passin, Tom]

[Charlie Reiman]

> Actually, this will work although it is wordy. <dtml-if=20
> somevar> is special and will evaluate to false if somevar is=20
> not defined.=20

Ah, I did not know that.  Nice.  Javascript is like that - undefined
variables return "undefined" which (along with null, 0, and "")
evaluates to false for logical tests, so using Javascript's
short-circuit logical evaluation, you can do things like

if (theVar && theVar.property){
	// the variable and its property both exist
}

>This is very different from <dtml-if "somevar">=20
> which will throw and exception if somevar is not defined.
>

Right.=20

> Having said that, using has_key is a lot cleaner.
>=20

Cheers,

Tom P=20