Re: exp?[whenTrue, whenFalse] instead of exp?choose(whenTrue, whenFalse)

Hi Daniel,

> I had a proposal to add exp?choose(whenTrue, whenFalse) in some of the
> next 2.3.x releases earlier. This is a substitute for the Java ternary
> operator, so it only evaluates one of its parameter expressions.
> 
> I think it should just become exp?[whenTrue, whenFalse] instead. Some
> may accuse me of perlism for that... But I think this is a frequent
> enough operation to warrant a dedicated operator.

Is this backward compatible? What happens when you write it in a template with current version?

-- Denis. 

> If you disagree, you might have to consider something about the 2.4
> series. My opinion is that ?string(...) is lame, because it's a
> template language, so its all about generating text. So you should
> able just write x?'0.00' instead of x?string('0.00'). That's maybe
> something for the 2.4 series. But how will you format booleans? Right
> now, with foo?string(whenTrue, whenFalse). After adding ?choose, you
> might as well write foo?choose(whenTrue, whenFalse), which is as
> verbose as with ?string, but somewhat smarter (lazy evaluation,
> non-string return values). Actually, you don't need anything for
> boolean formatting, if you have a ternary operator anyway. But since
> formatting a boolean is a typical task in templates, ?choose(t, f) is
> too verbose, just like ?string(...). So that's where ?[t, f] comes
> from; it's not only terser, but follows the logic of ?'0.00', that is,
> if you have a non-id token after `?`, it's formatting.
> 
> You may also wonder why exp?[t, f] instead of exp?(t, f). I don't want
> to waste ?(...) on this. In JavaScript, { foo: bar } is the same as
> { 'foo': bar }, so how do you specify a key that's the value of the
> variable foo instead? Like { (foo): bar }. Now that trick, i.e. making
> and identifier dynamic with parentheses is something I want to reserve
> for the future. Like if you have variable `f` holding a method, and
> you want to "apply" that on a value, you could write `x?(f)`. I think
> that's 

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