I work with scientists. They are usually very smart, unfortunately they are not necessarily very good programmers. But the snippet below made me post this here.
It is FORTRAN (scientists, you see?), and what it does is... well, it is part of the routine to read in a NetCDF file.
if (nvar.eq.5) then
var(i) = name
if (i.eq.1) call nf_inq_varid(ncid,var(i),lon_varid)
if (i.eq.2) call nf_inq_varid(ncid,var(i),lat_varid)
if (i.eq.3) call nf_inq_varid(ncid,var(i),lvl_varid)
if (i.eq.4) call nf_inq_varid(ncid,var(i),rec_varid)
if (i.eq.5) call nf_inq_varid(ncid,var(i),dat_varid)
For those unfamiliar with NetCDF files: Data is stored in named variables. Internally, these variables have an integer varid, by which they can be called.
Inside the loop, it first asks the netCDF library to return the name of the variable with the varid i. And then, it asks for the varid of the variable with that name.
The following would have done the same, but less complex:
DO i = 1, 5
That would have also made me realise far quicker that the netCDF file needs to have the varids in a specific order, which it shouldn't have to.
They are usually very smart, unfortunately they are not necessarily very good programmers
The code snippet you present is very common with "professional" programmers. The pattern has a name even "for-if antipattern", and featured on the frontpage http://thedailywtf.com/Articles/Switched_on_Loops.aspx
Consider yourself lucky! At least they are smart
What makes this for-if instance really special, though, is the wonderful way it makes no use of the names defined NetCDF file's names except for the specific purpose of looking up IDs it already has. It's the Sirius Cybernetics Corporation anti-pattern.