Make the store plugins more introspectable

Directly register the store classes rather than a function to build an
instance of them.
This gives the possibility to introspect static members of the class or
choose different ways of instantiating them.

1 files changed, 7 insertions, 11 deletions

diff --git a/src/libstore/dummy-store.cc b/src/libstore/dummy-store.cc
index 7a5744bc1..a677e201e 100644
--- a/src/libstore/dummy-store.cc
+++ b/src/libstore/dummy-store.cc
@@ -2,17 +2,15 @@
 
 namespace nix {
 
-static std::string uriScheme = "dummy://";
-
 struct DummyStore : public Store
 {
-    DummyStore(const Params & params)
+    DummyStore(const std::string uri, const Params & params)
         : Store(params)
     { }
 
     string getUri() override
     {
-        return uriScheme;
+        return uriPrefixes()[0] + "://";
     }
 
     void queryPathInfoUncached(const StorePath & path,
@@ -21,6 +19,10 @@ struct DummyStore : public Store
         callback(nullptr);
     }
 
+    static std::vector<std::string> uriPrefixes() {
+        return {"dummy"};
+    }
+
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override
     { unsupported("queryPathFromHashPart"); }
 
@@ -48,12 +50,6 @@ struct DummyStore : public Store
     { unsupported("buildDerivation"); }
 };
 
-static RegisterStoreImplementation regStore([](
-    const std::string & uri, const Store::Params & params)
-    -> std::shared_ptr<Store>
-{
-    if (uri != uriScheme) return nullptr;
-    return std::make_shared<DummyStore>(params);
-});
+[[maybe_unused]] static RegisterStoreImplementation<DummyStore> regStore();
 
 }