Variants.Unassigned
From RAD Studio VCL Reference
C++ Information
From Variants.hpp
System::Variant __fastcall Unassigned(void);
Unit: Variants
Type: function
Description
Returns an "empty" variant.
A variant variable can be "empty", meaning it has not yet been assigned to. The Unassigned function returns an empty variant, which can be assigned to a variant variable to restore the variable to its initial state.
Use the VarIsEmpty function to test whether a variant is empty. When used on an empty variant, the VarType standard function returns varEmpty.
If an empty variant is cast to another type (for example, by assigning to a non-variant variable or calling VarAsType) the following conversions occur:
| Destination | Conversion result |
|---|---|
|
Numeric type |
Zero |
|
String type |
Empty string |
|
Boolean |
False. |
Note: Unassigned is useful with variants referencing OLE Automation Objects that you want to keep "alive" until another value is assigned to the variant.
There's corresponding functionality under Linux. Should document when time permits.