Flag in _oasis are only boolean. As of OASIS 0.4.7, there is no way to define
a string flag. A string flag, can be useful when you want e.g.
CCOpt: -D $(STR).
The reason why this has not been done are:
- boolean flags are easy to switch on and off to test various branches, which can allow auto exploration for the package.
- string flags would require a way to validate them, make sure that quoting is correct when they are used in substitution.
- string flags are easily implementable directly in
setup.ml.
The quick solution to have a string flag FOO is to add the following code to
setup.ml:
(* OASIS_STOP *)
let _ = BaseEnv.var_define "FOO" (fun _ -> "123");;
let () = setup ();;
This can be used like this:
Executable "opam-build-revdeps"
Path: src/bin/opam-build-revdeps
MainIs: OPAMBuildRevdeps.ml
CompiledObject: best
CCOpt:-D $(FOO)
The value of the flag FOO can be set through command line and environment
variable.