About the parameter of API: PQprepared

In libpq, the definition is like:
PGresult *
PQprepare(PGconn *conn,
const char *stmtName, const char *query,
int nParams, const Oid *paramTypes)

Could we remove the parameter "nParams"?
e.g. "insert into foo(id, name, address) values ($1, $2, $3)"
PostgreSQL possibly can parse the prepared sql statement to get the real
paramters count.

Or, is there another alternate way?