Specifies a type which inherits a Wstring behavior
Syntax
Description
Extends Wstring declares
typename to inherit properties and behaviors of a
WString. Purpose is to allow users to create custom string types (with i.e. dynamic memory management) that can integrate well in to existing fbc compiler built ins (good interoperability with fbc's
WString type).
This declaration of such a UDT with a suitable
Cast operator will instruct compiler to convert the UDT to a
WString (in addition, other suitable operators as
Let,
[] (Pointer Index),
Len, ..., can be also declared).
WString behaviour can be inherited directly, or indirectly and singly from a base-type.
WString behaviour can be inherited by a UDT also extending
base_typename (a kind of pseudo multiple-inheritance).
By declaring a type (directly or indirectly) as
Extends Wstring (in addition to defining a suitable
Cast operator only), this promotes it fully
WString type compatible, even with
StrPtr/
SAdd,
LSet/
RSet, and
Select Case.
Example
Version
Dialect Differences
- Not available in the -lang qb dialect unless referenced with the alias __Extends __Wstring, but unusable because no member procedure is allowed in this dialect.
Differences from QB
See also