no `catch e MyException if e foo = 25 ` kotlinlang #announcements

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Title

v

vaskir

09/27/2018, 12:16 PM

no

catch (e: MyException if e.foo = 25) { .. }

??

r

robin

09/27/2018, 12:20 PM

Nope. But

catch (e: MyException) {
   if (e.foo == 25) {
   ...
   }
}

works fine.

v

vaskir

09/27/2018, 12:20 PM

🙂

r

robin

09/27/2018, 12:20 PM

...except you'll probably need to rethrow in the else block to imitate your example.

v

vaskir

09/27/2018, 12:23 PM

try {
//    ...
} catch (e: MyException) {
    if (e.code == 25) {
        // do specific stuff
    } else {
        // do common stuff
    }

} catch (e: Exception) {
    // do common stuff
}

so I have to duplicate "do common stuff"

if C#/F# there are guards

like this:

try 
    ...
with 
| :? Exn1 as e when e.bar = 23 -> ...
| FooException(25) -> ...
| _ -> ...

r

robin

09/27/2018, 12:27 PM

That's not really possible in kotlin, unfortunately. If you're already catching

Exception

though, you can do this instead:

try {
//    ...
} catch (e: Exception) {
    if (e is MyException && e.code == 25) {
        // do specific stuff
    } else {
        // do common stuff
    }
}

v

vaskir

09/27/2018, 12:28 PM

ah, this looks better

thanks

r

robin

09/27/2018, 12:30 PM

No problem

Oh and you can of course also use a

when

statement instead if you have more cases to check.

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