It would be nice if there was a native fme transformer to intelligently join file path components, similar to python's os.path.join.
ie concatenate all the parts with exactly one directory separator ( or /) unless already included in the part, ignore empty parts except the last.
So something like
attr1: d:
attr2: dir1
attr3: dir2
attr4: dir3dir4
attr5: {missing}
attr6: file.ext
would become d:dir1dir2dir3dir4file.ext
Even better if it could work with either a series of attributes or a list