FUNCTION (Member)


Declares or defines a member procedure returning a value.

Syntax:
{ Type | Class | Union } typename
declare [ static | const ] Function fieldname [calling convention specifier] [ alias external_name ] ( [ parameters ] ) [ byref ] as datatype [ Static ]
End { Type | Class | Union }

Function typename.fieldname ( [ parameters ] ) [ byref ] as datatype [ Export ]
statements
End Function

Parameters:
typename
name of the Type, Class, or Union
fieldname
name of the procedure
external_name
name of field as seen when externally linked
parameters
the parameters to be passed to the procedure
calling convention specifier
can be one of: Cdecl, Stdcall or Pascal

Description:
Function members are accessed with Operator . (Member access) or Operator -> (Pointer to member access) to call a member procedure that returns a value (a reference can also be returned by specifying byref as return_type). The procedure may optionally accept parameters either byval or byref. typename be overloaded without explicit use of the Overload keyword.

typename is the name of the type for which the Function method is declared and defined. Name resolution for typename follows the same rules as procedures when used in a Namespace.

A hidden this parameter having the same type as typename is passed to non-static member procedures. this is used to access the fields of the Type, Class, or Union.
To access duplicated symbols defined outside the Type, add one (or two) dot(s) as prefix: .SomeSymbol (or ..SomeSymbol if inside a With..End With block).

A Static (Member) may be declared using the Static specifier. A Const (Member) may be declared using the Const specifier.

As for a normal Function, the return value of a Function member can be ignored in the calling code.

Examples:
#include "vbcompat.bi"

Type Date

  value As Double

  Declare Static Function Today() As Date

  Declare Function Year() As Integer
  Declare Function Month() As Integer
  Declare Function Day() As Integer

End Type

Function Date.Today() As Date
  Return Type(Now())
End Function

Function Date.Year() As Integer
  Return ..Year(value)
End Function

Function Date.Month() As Integer
  Return ..Month(value)
End Function

Function Date.Day() As Integer
  Return ..Day(value)
End Function

Dim d As Date = Date.Today

Print "Year  = "; d.Year
Print "Month = "; d.Month
Print "Day   = "; d.Day


Dialect Differences:
See also:
Back to User Defined Types
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