Entity Name Functions

Entity Name Functions

Entity Context and Coordinate Transform Data

 

AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Name Functions > 

Entity Handles and Their Uses

The handent function retrieves the name of an entity with a specific handle. As with entity names, handles are unique within a drawing. However, an entity's handle is constant throughout its life. AutoLISP applications that manipulate a specific database can use handent to obtain the current name of an entity they must use. You can use the DDMODIFY command to get the handle of a selected object.

The following code fragment uses handent to obtain and display an entity name.

(if  (not (setq e1  (handent "5a2")))

  (princ "\nNo entity with that handle exists. ")

  (princ e1)

)

In one particular editing session, this code fragment might display the following:

<Entity name: 60004722>

In another editing session with the same drawing, the fragment might display an entirely different number. But in both cases the code would be accessing the same entity.

The handent function has an additional use. Entities can be deleted from the database with entdel (see Entity Context and Coordinate Transform Data). The entities are not purged until the current drawing ends. This means that handent can recover the names of deleted entities, which can then be restored to the drawing by a second call to entdel.

Entities in drawings that are cross-referenced by way of XREF Attach are not actually part of the current drawing; their handles are unchanged but cannot be accessed by handent. However, when drawings are combined by means of INSERT, INSERT *, XREF Bind (XBIND), or partial DXFIN, the handles of entities in the incoming drawing are lost, and incoming entities are assigned new handle values to ensure each handle in the current drawing remains unique.