OpenEdge Development:<br />Progress Dynamics Advanced Development Link support methods

Link support methods

There are several additional methods that are used to modify and support links, including the following.

removeLink, removeAllLinks, removeUserLinks

These functions delete one or links from an object. The removeLink function removes a specific link between two objects, as shown:

Procedure removeLink: Parameters: INPUT phSource AS HANDLE -- source procedure handle, INPUT pcLink AS `CHARACTER` -- link type name, INPUT phTarget AS HANDLE -- link target object handle Candidate for: calling If your code needs to remove a specific link between two objects, it should use this call.

Procedure removeLink: 
  Parameters:  INPUT phSource AS HANDLE -- source procedure handle, 
               INPUT pcLink   AS CHARACTER -- link type name,  
               INPUT phTarget AS HANDLE -- link target object handle 
  Candidate for: calling 
    If your code needs to remove a specific link between two objects, it should 
use this call.

Your code does not normally run removeAllLinks, which deletes all standard (supported) links from an object. This includes deleting link definitions in the objects at the other end of the links, which is done automatically when the object is destroyed.

The procedure removeUserLinks removes user-defined links, which are not on the SupportedLinks list.

assignLinkProperty

This LOGICAL property sets a property value in an object at the other end of a specified link, relative to the current object (TARGET-PROCEDURE), as shown:

Function assignLinkProperty() Parameters: INPUT pcLink AS `CHARACTER` -- Link Type, INPUT pcPropName AS `CHARACTER` -- Property Name, INPUT pcPropValue AS `CHARACTER` -- Property Value. Returns: `LOGICAL` (success flag) Candidate for: calling You can use this function when you know the name of the link that connects the current object to another, but not the handle of the object at the other end of the link. This allows you to set the property based on the relationship between the objects without having to retrieve the handles. If there’s more than one object at the other end of the link, the property is set in all of them.

Function assignLinkProperty() 
  Parameters:  INPUT pcLink AS CHARACTER -- Link Type,  
               INPUT pcPropName AS CHARACTER -- Property Name,  
               INPUT pcPropValue AS CHARACTER -- Property Value. 
  Returns: LOGICAL (success flag) 
  Candidate for: calling 
    You can use this function when you know the name of the link that connects 
the current object to another, but not the handle of the object at the other 
end of the link. This allows you to set the property based on the relationship 
between the objects without having to retrieve the handles. If there’s more 
than one object at the other end of the link, the property is set in all of 
them.

linkHandles

This CHARACTER function takes a link name and returns a list of handles of objects at the other end of that link, relative to the current object (the TARGET-PROCEDURE), as shown:

Function linkHandles() Params: pcLink AS `CHARACTER` -- Link name (including "-SOURCE" or "-TARGET") Candidate for: calling Your code can use this function to retrieve a list of the procedure handles of the object or objects connected to the current object (the one the function is invoked in) by the link you specify. This could be useful if you need to do something beyond just setting a property value (for which you could use assignLinkProperty).

Function linkHandles() 
   Params: pcLink AS CHARACTER -- Link name (including "-SOURCE" or "-TARGET") 
   Candidate for: calling 
    Your code can use this function to retrieve a list of the procedure handles 
of the object or objects connected to the current object (the one the function 
is invoked in) by the link you specify. This could be useful if you need to 
do something beyond just setting a property value (for which you could use 
assignLinkProperty).

linkProperty

This CHARACTER function returns the value of the requested property in the object at the other end of the specified link, relative to the TARGET-PROCEDURE. Parallel to the assignLinkProperty function, this one retrieves the value of a property using the link name rather than the object’s handle.

If there is more than one object at the other end of the link (or none), the function returns blank, as shown:

Function linkProperty() Params: INPUT pcLink AS `CHARACTER` -- Link name, INPUT pcPropName AS `CHARACTER` -- Property name. Candidate for: calling You can invoke this function in your code to retrieve a property value when you know the link that associates two objects but not the handle of the object at the other end of the link.

Function linkProperty() 
   Params:  INPUT pcLink     AS CHARACTER -- Link name, 
            INPUT pcPropName AS CHARACTER -- Property name. 
 Candidate for: calling 
    You can invoke this function in your code to retrieve a property value 
when you know the link that associates two objects but not the handle of the 
object at the other end of the link.