Modifying Extended Entity Data

Once the extended entity data has been retrieved using the ENTGET function, the programmer is free to modify any portion or all of the information using the list and association list functions previously discussed. At this point the extended entity data is treated just as the association list data was in Chapter Four. The dotted pair containing the old data is first obtained using the ASSOC function. Next, the new dotted pair is created using the CONS function and the two are switched using the SUBST function. Finally, the changes are recorded in the drawing database using the ENTMOD function. Using the extended entity data from the previous example the following expressions would be used to replace the dotted pair (1041 . 14.5) with the dotted pair (1041 . 0.0125).