[fpc-devel] new features and facilities

[Michael Van Canneyt]

On Fri, 9 Oct 2015, Sven Barth wrote:

> Am 08.10.2015 23:48 schrieb "Michael Van Canneyt" <michael at freepascal.org>:
>> Actually, yes I think C's or Javascript's ternary is better suited.
>>
>> Let me explain. If I see
>>
>> If expr1 then expr2 else expr3
>>
>> it says 'statement' to me. But
>>
>> a ? b : c;
>>
>> Says "expression" to me.
>>
>> So
>>
>> left := a ? b : c;
>
> That's probably only because other languages use that as the ternary.

No, it is because there are no keywords involved.

The keyword "If" starts a statement. It's a simple rule.

As I said: by using "if" in an expression, you break the rule and introduce ambiguity.

> There also another reason why I prefer the variant with the if: ease to
> implement in the compiler.
>
> For the if one merely needs to add a corresponding case in factor() while
> for the ?: one needs to fiddle with the compiler's operator precedence
> rules that are applied in sub_expr() which can lead to desaster either
> during implementation or later on when bugs are discovered...

I don't see how the use of "if" differs from "?" in rules of precedence, they are at the exact same level.
They're both just tokens to the compiler. 
At least "?" has the advantage of being new and not yet used, so is unambiguously.

Michael.