Re: Test if variable has void value

2018-08-22 Thread Rene Zwanenburg via Digitalmars-d-learn 

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

Test if variable has void value

2018-08-22 Thread Andrey via Digitalmars-d-learn 

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.