The __if_not_exists Statement
__if_not_exists allows you to conditionally include code depending on whether the specified symbol does not exist.
__if_not_exist (variable) {
statements
}
where:
variable
The symbol whose existence you want to test for.statements
One or more statements to execute if variable does not exists.
Remarks
__if_not_exists can be applied to identifiers both inside of and outside of a class. When testing for overload functions, you cannot test for a specific form of the overload.
__if_not_exists should only be used within the body of a function. Outside of the body of a function __if_not_exists can only refer to fully defined types.
__if_exists allows you to conditionally include code depending on whether the specified symbol exists.
Example
See __if_exists for an example of how to use __if_not_exists.