Creates a "combined" structure from main and default_. The combined structure contains member values from main whenever !isNull for this value and otherwise values from default_.
Creates a "combined" structure from main and default_. The combined structure contains member values from main whenever !isNull for this value and otherwise values from default_. Assertion error if both a member of main and of default_ are null.
Creates a "combined" structure from main and default_. The combined structure contains member values from main whenever !isNull for this value and otherwise calculated values from default_. Assertion error if both a member of main and of default_ are null.
Defines means to pass structs with default values that may be unspecified.