Basically, what it does is using environment variable substitution for simulating:
case %var% of 1: rem do something 2: rem do something else 3: rem do something completely different end
The code looks like this:
call :SomePrefix%var% goto aftercase :SomePrefix1 rem do something goto :eof :SomePrefix2 rem do something else goto :eof :SomePrefix3 rem do something completely different goto :eof :aftercase
If “do something” is some complex code that’s pretty nifty and possibly a bit faster than the naive approach:
if "%var%"=="1" rem do something if "%var%"=="2" rem do something else if "%var%"=="3" rem do something completely different
But still: The readability suffers quite a lot. And if speed was an issue, why would you use a batch file in the first place? Anyway, I had a use case for it so I used it.