[CMake] doing simple math in cmake or useless foreach( RANGE )

[Hendrik Sattler]

Hi,

either I cannot find it or it's not there: doing simple mathematic things like 
substract 1 from a variable.

If that's not present, I do not understand how
LIST( LENGTH MYLIST COUNT )
FOREACH ( index RANGE ${COUNT} )
list ( GET MYLIST ${index} entry )
....

will address non-present indexes in the list. I would the above statement 
cover the range from 0 to COUNT-1 but it also cover COUNT itself like said in 
the documentation. Does that actually make sense as the variable in the 
documentation is called "total" but the loop count is "total+1"?

Currently I use a
  if ( LESS )
work-around but that looks like a hack.

Any ideas?

HS