Batch Linked variable Extraction demo

REM Batch script demonstrating extraction of values from linked variables
REM explanation of the concepts here: https://stackoverflow.com/a/61024682/12343998

@echo off

Set Zero=One
Set One=Two
Set Two=Three
set Three=Four
set Four=Five
set Five=Six
set Six=Seven
set Seven=Eight
set Eight=Nine
Set Nine=Ten
Set Ten=Eleven
Set Eleven=Twelve
Set Twelve=Thirteen. Last variable. Cannot Be reached from depth 0

Goto :main

REM Subroutine to Build Expansion String based on depth:

:extract <Starting Variable> < Call Depth Range 1 to 11 > <Variable to Assign>
    Setlocal EnableDelayedExpansion
    Set "Assign=%~1"
    Set EXPcount=1
    Set "CALLcount=%~2"
    IF Not "!CALLcount!"=="0" Set /A EXPcount=( !CALLcount! * 4 ) - 1
    For /L %%A in (1,1,!EXPcount!) do (Set "Assign=%%!Assign!%%")

    Setlocal DisableDelayedExpansion
    Set "Assign=Set Assign=!Assign!"
    (
    Endlocal
        Set "Assign=%Assign%"
    )

    For /L %%B in (0,1,!CALLcount!) do (Set "Assign=CALL !Assign!")
    !Assign! || (Echo String exceeds line length, No Modification. & Exit /B)
    IF "!Assign!"==" " (Echo Variable Not Defined, No Modification. & Exit /B)
    (
    Endlocal
        Set "%~3=%Assign%"
        Exit /B
    )


REM Expand variable using relationship between Number of Calls and % Expansion Required to Parse variable
:main
Setlocal EnableDelayedExpansion

REM Define variable 'Depth Shortcut' to target specific depths
For %%A in (0 1 2 4 8 16 32 64 128 256 512 1024) Do (
    Set /A #+=1
    Set Depth[!#!]=%%A
)

REM iterate over all depths
For /L %%E in (1,1,!#!) do (
    Call :Extract Zero !Depth[%%E]! New
    Echo(Start: Zero Depth: %%E, Extracted Value: !New!
)
ECHO.
REM extract from selected depth levels
For %%E in (5 8 11) do (
    Call :Extract Zero !Depth[%%E]! New
    Echo(Start: Zero Depth: %%E, Extracted Value: !New!
)
ECHO.
REM extract from selected depth levels, From a different starting Variable
For %%E in (5 6 7 8 9) do (
    Call :Extract five !Depth[%%E]! New
    Echo(Start: Five Depth: %%E, Extracted Value: !New!
)
Endlocal
Echo(Example Complete
Pause >nul