FUNCTION (Member)

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgMemberFunction
• Last revised: 2021-09-28

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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 as global outside the Type, add one or preferably two dot(s) as prefix: .SomeSymbol or preferably ..SomeSymbol (or only ..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

start GeSHi

#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

end GeSHi

Dialect Differences

• Only available in the -lang fb dialect.

See also

• Class
• Function
• Sub (Member)
• Type

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