Should this Compile?

[H. S. Teoh]

On Tue, Oct 03, 2017 at 10:37:17PM +0000, SamwiseFilmore via Digitalmars-d-learn wrote:
[...]
>     string toString() {
>         return
>             this.value.toString() ~
>             " of " ~
>             this.suit.toString() ~
>             this.suit == CardSuit.diamonds ? "" : "\t" ~
>             "\tfacing " ~
>             this.facing.toString();
>     }
[...]
> This code does not compile with this error message: Error:
> incompatible types for ((toString(this.p_value) ~ " of " ~
> toString(this.p_suit)) ~ (this.p_suit)): 'string' and 'CardSuit'
> 
> Am I using the ternary operator correctly here, or is this an issue
> with dmd? I'm using dmd v2.076.0.

When in doubt, always parenthesize around the ?: operator to prevent
ambiguities.  I'd write that line as:

	... ~ ((this.suit == CardSuit.diamonds) ? "" : "\t") ~ ...

It's a few characters more, but will save you headaches from obscure
errors caused by unexpected operator precedences.


T

-- 
A linguistics professor was lecturing to his class one day.
"In English," he said, "A double negative forms a positive. In some
languages, though, such as Russian, a double negative is still a
negative. However, there is no language wherein a double positive can
form a negative."
A voice from the back of the room piped up, "Yeah, yeah."