Just use awk, it's much simpler than grep in letting you clearly express compound conditions.
If you want to skip lines that contains both loom
and gloom
:
awk '/loom/ && !/gloom/{ print FILENAME, FNR, $0 }' ~/projects/**/trunk/src/**/*.@(h|cpp)
or if you want to print them:
awk '/(^|[^g])loom/{ print FILENAME, FNR, $0 }' ~/projects/**/trunk/src/**/*.@(h|cpp)
and if the reality is you just want lines where loom
appears as a word by itself:
awk '/\<loom\>/{ print FILENAME, FNR, $0 }' ~/projects/**/trunk/src/**/*.@(h|cpp)