registrar: define revsetpredicate to decorate revset predicate revsetpredicate is used to replace revset.predicate and revset.extpredicate in subsequent patches. This patch also adds loadpredicate() to revset, because this combination helps to figure out how the name of safe predicate is put into safesymbols. This patch still uses safesymbols set to examine whether the predicate corresponded to the 'name' is safe from DoS attack or not, because just setting func._safe property needs changes below for such examination. before: name in revset.safesymbols after: getattr(revset.symbols.get(name, None), '_safe', False) "automatic registration" described in help doc of revsetpredicate class will be achieved by the subsequent patch, which lists loadpredicate() up in dispatch.extraloaders.