How to test if a trade object is null in CBT?

[jantor]

My goal: I have a symbol on which I need to enter position, but I need to check if there is an open position . I tried this:

for( openpos = bo.GetFirstOpenPos(); openpos; openpos = bo.GetNextOpenPos() )
{
    if (NOT openpos)
// and this
    if (IsNull(openpos))

neither worked

I had to do this:

if (openpos)
{}
else
{
    ... // my code here
}

Is there a better solution?

[Tomasz]

Something is wrong with your code elsewhere because openpos inside loop would ALWAYS be set and outside loop will NEVER be set because the continuation condition inside for( ; openpos /* HERE */; ) causes that openpos is ALWAYS valid inside loop.

for( openpos = bo.GetFirstOpenPos(); openpos; openpos = bo.GetNextOpenPos() )
{
 // openpos inside this loop is ALWAYS valid !
}
//outside loop openpos is NOT set always because that's loop termination condition!

BTW: openpos it an OBJECT, not boolean or number.

[jantor]

Sorry, I posted the wrong code. Here is the correct one:

trade = bo.FindOpenPos(symbol);

Then the question of how to test if the trade object is null.
The code in the OP was actually my workaround when I could not find a way to test it.

[Tomasz]

As I wrote, this is an OBJECT, not a number or boolean, it does not have a numerical or boolean "value". Therefore you can only use it to test it if is VALID this way:

if( object )
{
  // object valid you can use object
}
else
{
  // object is NOT valid you can NOT use it
}

This is possible because if() understands if object is valid or not, but "validity" has no numerical value that you could compare to.

[jantor]

Thanks, Tomasz. Now it is clear to me that a trade object cannot be compared to a numerical value.

The question becomes, how do we find out if we have an open position with a given symbol? Since we have the bo.FindOpenPos() function, logically we should be able to do that easily, or am I missing something? Thanks.