• Andrey (4/10) Aug 22 2018 Tried this:
• Rene Zwanenburg (8/18) Aug 22 2018 You can't. When using a void initializer the actual value is

Andrey <saasecondbox yandex.ru> writes:

Hello,
How to test if variable has void value?

 string text = void;
if(text == void)
{
    writeln("Is void");
}

Tried this:
if(is(text == void))

but doesn't work.

Rene Zwanenburg <renezwanenburg gmail.com> writes:

On Wednesday, 22 August 2018 at 13:50:07 UTC, Andrey wrote:
 Hello,
 How to test if variable has void value?

 string text = void;
if(text == void)
{
    writeln("Is void");
}

 Tried this:
if(is(text == void))

 but doesn't work.

You can't. When using a void initializer the actual value is 
garbage until initialized properly, and that garbage can look 
like anything including a valid instance.

So if the flow of your program can't guarantee that the value has 
been initialized at a certain point, you'll have to track it 
yourself some way. Nullable may be of help:

https://dlang.org/phobos/std_typecons.html#Nullable