Check if a variable exists

Peter Thomassen info at
Fri Aug 18 12:25:04 PDT 2006

Kirk McDonald schrieb am Freitag, 18. August 2006 21:14:
>> Is it possible to check if a variable exists, like PHP's isset()?
> Typically, you only ever have to ask when doing fairly complex template
> stuff; this is largely the point of a statically-typed language. Mind if
> I ask why you need to check for this?

I've got a for loop which contains an if statement checks something
depending on the counting loop var i. If true, some action producing a
temporary variable is taken.

After the for loop, I want to do further things if and only if the "if" tree
has been entered at least once. I cannot check that using i because that
has modified during the loop. Of course I could declare a bool in the "if"
tree and check for that, but I know that I will have the temporary variable
set, if the "if" tree has been entered. So, why not check for this?

> The answer, though, is this: 
> static if (is(typeof(my_variable))) {
>      // ...
> }

Thanks. What is the static keyword for?

More information about the Digitalmars-d-learn mailing list