An application can obtain the extended data (xdata) that it has attached to an entity with entget.
The entget function can return an entity’s definition data and the xdata for the applications it requests. It requires an additional argument, application, that specifies the application names. The names passed to entget must correspond to applications registered by a previous call to regapp; they can also contain wild-card characters.
By default, associative hatch patterns contain xdata. The following example code demonstrates the association list of this xdata. Before you can use the code, create a closed boundary and apply an associative hatch object to the boundary.
(entget (car (entsel)) '("ACAD"))
Select object: Select an associative hatch
Entering the preceding code at the command line returns a list that looks something like this:
((-1 . <Entity name: 7ffffb05e10>) (0 . "HATCH") (330 . <Entity name: 7ffffb039f0>) (5 . "1D9") (100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "0") (100 . "AcDbHatch") (10 0.0 0.0 0.0) (210 0.0 0.0 1.0) (2 . "ANSI31") (70 . 0) (71 . 1) (91 . 1) (92 . 7) (72 . 0) (73 . 1) (93 . 4) (10 31.2567 17.3197 0.0) (10 7.77575 17.3197 0.0) (10 7.77575 8.83313 0.0) (10 31.2567 8.83313 0.0) (97 . 1) (330 . <Entity name: 7ffffb05d50>) (75 . 1) (76 . 1) (52 . 0.0) (41 . 3.0) (77 . 0) (78 . 1) (53 . 0.785398) (43 . 0.0) (44 . 0.0) (45 . -0.265165) (46 . 0.265165) (79 . 0) (47 . 0.0289642) (98 . 1) (10 21.1106 14.5391 0.0) (-3 ("ACAD" (1010 0.0 0.0 0.0))))
The following example code demonstrates a typical sequence for retrieving xdata for two specified applications. Note that the application argument accepts application names in list form:
(setq working_elist
(entget ent_name
'("MY_APP_1" "SOME_OTHER") ; Only xdata from "MY_APP_1"
) ; and "SOME_OTHER" is retrieved.
)
(if working_elist
(progn
... ; Updates working entity groups.
(entmod working_elist) ; Only xdata from registered
) ; applications still in the
) ; working_elist list are modified.
As the example code demonstrates, you can modify xdata retrieved by entget by using a subsequent call to entmod, just as you can use entmod to modify normal entity definition data. You can also create xdata by defining it in the entity list passed to entmake. Returning the xdata of only those applications specifically requested protects one application from corrupting another application's data. It also controls the amount of memory that an application needs to use and simplifies the xdata processing that an application needs to perform.