Using Procedures, Functions and Properties

The following describes the basic use of procedures, functions and properties in LibreOffice Basic.

note

When you create a new module, LibreOffice Basic automatically inserts a Sub called "Main". This default name has nothing to do with the order or the starting point of a LibreOffice Basic project. You can also safely rename this Subroutine.


note

Se aplican algunas restricciones a los nombres de sus variables p煤blicas, subrutinas, funciones y propiedades. No debe emplear el mismo nombre que otro de los m贸dulos de la misma biblioteca.


Procedures (Subroutines) functions (Function) and properties (Property) help you maintaining a structured overview by separating a program into logical pieces.

Un beneficio de los procedimientos, funciones y propiedades es que, una vez ha desarrollado un c贸digo de programaci贸n que contiene componentes, puede reutilizar este c贸digo en otro proyecto.

Pasar variables a procedimientos, funciones o propiedades

Variables can be passed to both procedures, functions or properties. The Sub Function or Property must be declared to expect parameters:


  Sub SubName(Parameter1 As TYPENAME, Parameter2 As TYPENAME,...)
      ' su c贸digo va aqu铆
  End Sub

Se llama a la Sub mediante la sintaxis siguiente:


  [Call] SubName( [Parameter1:=]Value1, [Parameter2:=]Value2, ...)

The parameters passed to a Sub must fit to those specified in the Sub declaration.

El mismo proceso se aplica a una Function. As铆 tambi茅n, las funciones siempre devuelven un resultado de funci贸n. El resultado de una funci贸n se define asignando el valor de retorno al nombre de la funci贸n:


  Function FunctionName(Parameter1 As TYPENAME, Parameter2 As TYPENAME,...) As TYPENAME
      ' su c贸digo va aqu铆
      FunctionName=Result
  End Function

Se llama a la Function mediante la sintaxis siguiente:


  Variable = FunctionName( [Parameter1:=]Value1, [Parameter2:=]Value2, ...)

Properties combine the syntax of procedures and functions. A Property usually requires up to one parameter.


  Private _IsApproved As TYPENAME
  Property Get IsApproved As TYPENAME
      ' su c贸digo va aqu铆
      IsApproved = some_computation
  End Property
  Property Let IsApproved(value As TYPENAME)
      ' su c贸digo va aqu铆
      _IsApproved = computed_value
  End Property

Se llama a la Property mediante la sintaxis siguiente:


  var = IsApproved
  IsApproved = some_value
tip

You can also use the fully qualified name to call a procedure, function or property:
[Call] Library.Module.Macro(), where Call is optional.
For example, to call the Autotext macro from the Gimmicks library, use the following command:
Gimmicks.AutoText.Main()


Pasar variables por valor o por referencia

Parameters can be passed to a procedure, a function or a property either by reference or by value. Unless otherwise specified, a parameter is always passed by reference. That means that a Sub, a Function or a Property gets the parameter and can read and modify its value.

If you want to pass a parameter by value insert the key word ByVal in front of the parameter when you call a Sub, a Function or a Property, for example:


  Function ReadOnlyParms(ByVal p2, ByVal p2)
      ' su c贸digo va aqu铆
  End Function
  result = ReadOnlyParms(parm1, parm2)

In this case, the original content of the parameter will not be modified by the Function since it only gets the value and not the parameter itself.

Definir par谩metros opcionales

Es posible definir funciones, procedimientos o propiedades con par谩metros opcionales; por ejemplo:


  Sub Rounding(number, Optional decimals, Optional format)
      ' su c贸digo va aqu铆
  End Sub

Positional or Keyword Arguments

When you call a function or a subroutine, you may pass its arguments by position or by name. Passing by position means just listing the arguments in the order in which the parameters are defined in the function or subroutine. Passing by name requires you to prefix the argument with the name of the corresponding parameter followed by a colon and an equal sign (:=). Keyword arguments may appear in any order. Refer to Basic Replace() function for such examples.

When needing to pass less parameters, use keywords arguments. Passing values for fewer parameters by position requires to supply values for all parameters before them, optional or not. This ensures that the values are in the correct positions. If you pass the parameters by name - using keyword arguments - you may omit all other intermediate arguments.

脕mbito de variables

A variable defined within a Sub, a Function or a Property, only remains valid until the procedure is exited. This is known as a "local" variable. In many cases, you need a variable to be valid in all procedures, in every module of all libraries, or after a Sub, a Function or a Property is exited.

Declaring Variables Outside a Sub a Function or a Property


Global VarName As TYPENAME

La variable es v谩lida mientras dure la sesi贸n de LibreOffice.


Public VarName As TYPENAME

La variable es v谩lida en todos los m贸dulos.


Private VarName As TYPENAME

La variable solo es v谩lida en este m贸dulo.


Dim VarName As TYPENAME

La variable solo es v谩lida en este m贸dulo.

Ejemplo para variables privadas

Fuerce que las variables privadas lo sean en todos los m贸dulos estableciendo CompatibilityMode(True).


  ' ***** Module1 *****
  Private myText As String
  Sub initMyText
      miTexto = "Hola"
      Print "En m贸dulo1 : ", miTexto
  End Sub
   
  ' ***** Module2 *****
  'Option Explicit
  Sub demoBug
      CompatibilityMode( True )
      initMyText
      ' Ahora devuelve una cadena vac铆a
      ' (o produce un error con Option Explicit)
      Print "Ahora en m贸dulo2 : ", miTexto
  End Sub

Guardar el contenido de una variable luego de salir de una Sub, una Function o una Property


  Static VarName As TYPENAME

The variable retains its value until the next time the a Function, Sub or Property is entered. The declaration must exist inside a Sub, a Function or a Property.

Specifying the Return Value Type of a Function or a Property

As with variables, include a type-declaration character after the function name, or the type indicated by As and the corresponding data type at the end of the parameter list to define the type of the function or property's return value, for example:


  Function WordCount(WordText As String) As Integer

隆Necesitamos su ayuda!