Discussing Dimension driven in CAD

Please refer to the following picture

I think only Lee Mac can realize！

What is the purpose of this?... I normally draw things I don't want to modify, and then just dimension them and that's it... If somethings wrong I repeat the process from start of wrong things that are drawn... I bet I can finish the job faster than with above posted examples for modifications...

Powerful !

here is a simple .

;;;author : BDYCAD
;;;2005-03-18
(defun c:tt(/ BLB EP ESPL N-EP N-SP NEW-T SD SD-DXF SEA SEB SP SS1 SS2 SS3)
 (setq SD (entsel "\nChoose dimension:"))
 (if SD
   (PROGN
     (SETQ SD-DXF (ENTGET (CAR SD)))
     (WHILE (NOT (wcmatch (CDR (ASSOC 0 SD-DXF)) "*DIM*"))
(setq SD (entsel "\nChoose dimension:"))
(SETQ SD-DXF (ENTGET (CAR SD))))
     (SETQ SP (CDR (ASSOC 13 SD-DXF))
    EP (CDR (ASSOC 14 SD-DXF))
    ESPL (DISTANCE SP EP)
    SEA (ANGLE SP EP)
    SEB (ANGLE EP SP)
    NEW-T (getdist "\nNew value:"))
     (while (eq nil NEW-T)
(setq  NEW-T (getdist "\nNew value:")))
     (if NEW-T
(progn
     (setq BLB (* 0.5 (abs (-  NEW-T ESPL))))
     (if (> ESPL NEW-T )
(setq N-SP (POLAR SP SEA BLB)
      N-EP (POLAR EP (+ PI SEA) BLB))
(setq N-SP (POLAR SP SEB BLB)
      N-EP (POLAR EP (+ PI SEB) BLB))
)
     (setvar "osmode" (logior (getvar "osmode") 16384))
     (setvar "cmdecho" 0)
     (vl-cmdf "_.undo" "_group")
     (SETQ SS1 (SSGET "C" (POLAR SP (+ PI (* 0.25 PI)) 0.4)(POLAR SP (* 0.25 PI) 0.4))
    SS2 (SSGET "C" (POLAR EP (+ PI (* 0.25 PI)) 0.4)(POLAR EP (* 0.25 PI) 0.4))
    )
     (IF SS1
(COMMAND "STRETCH" (SSGET "C" (POLAR SP (+ PI (* 0.25 PI)) 0.4)(POLAR SP (* 0.25 PI) 0.4)) 
  ""SP N-SP))
     (IF SS3
(COMMAND "STRETCH" (SSGET "C" (POLAR EP (+ PI (* 0.25 PI)) 0.4)(POLAR EP (* 0.25 PI) 0.4)) 
  ""EP N-EP))
     (vl-cmdf "_.undo" "_end")
     (setvar "osmode" (logand (getvar "osmode") 49151))
     (PRINC"\nComplete!")))
     )
   )
 (princ)
 )

This is built into AutoCAD with parametric dimensions.

This is built into AutoCAD with parametric dimensions.

yes, parametric dimensions can do ,but is inconvenient. I'm sure OP' s demo is not use parametric dimensions.

yes, parametric dimensions can do ,but is inconvenient. I'm sure OP' s demo is not use parametric dimensions.

I would be interested in hearing how parametric dimensions are inconvenient. They are as easy to apply as a regular dimension.

Inconvenient = don't know how to use.

Inconvenient = don't know how to use.

They're awesome, especially for Dynamic Blocks. Can be very powerful.

I mean "Relative" ,dimensional constraints + geometric constraints. isn't ?