Some languages which don't support the conditional operator or if/else
expressions have an Iif function (or similar) instead.
If generics are added to Go, it might be worth including something like
this in the standard library to cut down on boilerplate for simple cases:
// in a package called 'gen' say
func Iif(type T) (cond bool, t1, t2 T) T {
if cond {
return t1
}
return t2
}
// usage
x := 3
...
y := gen.Iif(x > 2, 4, 5) // T inferred to be int, assigns 4 to y
You can, of course, do this now with interface{} but it's not type-safe and
requires a type assertion on assignment.
A drawback is that it would require the overhead of a function call unless
the Go compiler could inline simple stuff such as this.
Alan
On Wednesday, December 19, 2018 at 8:09:35 PM UTC, Viktor Kojouharov wrote:
>
> Hello,
>
> I've tried and failed at finding any previous discussion on this topic, so
> do point me to one if it exists.
>
> I'm interested to know whether it was considered (I can't imagine that it
> wasn't) for if and switch statements to be expressions instead, and if so,
> why were they ultimately left as statements. It seems to me that having
> them as expressions will not cause a significant change in how they are
> ultimately used, mostly because other languages that do support such
> expressions do not exhibit this behaviour either. Nor is such a change
> strictly backwards incompatible, since any expression is also technically a
> statement as well, via the ExpressionStmt grammar rule. Such expressions
> also cover a simple feature which a lot of people new to the language are
> looking for, and most of us have abused in other languages - ternary
> operators. The Go FAQ states that if-elses are clearer, if longer, which I
> definitely agree with. Yet it seems that an if expression would retain its
> readability, if not outright increase it, while allowing for terser
> assignments. The reason being that a chunk of repeatable code (for example
> assigning to the same variable in every logical branch) would be moved out
> of the whole block, thus highlighting the value.
>
> What if the spec defines that if all if-else blocks / all switch case
> clauses contain only single expression, they would be expressions rather
> than statements. How would that negatively impact the language, in a way
> that can't already be reproduced?
>
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