Tweak fromPreserve for floats and objects

src/preserves.nim

@@ -663,7 +663,7 @@ proc toPreserve*[T](x: T; E = void): Preserve[E] =
     for v in x.items: result.sequence.add(toPreserve(v, E))
   elif T is bool:
     result = Preserve[E](kind: pkBoolean, bool: x)
-  elif T is float:
+  elif T is float32:
     result = Preserve[E](kind: pkFloat, float: x)
   elif T is float64:
     result = Preserve[E](kind: pkDouble, double: x)
@@ -796,10 +796,6 @@ proc fromPreserve*[T, E](v: var T; pr: Preserve[E]): bool =
     if pr.kind == pkSignedInteger:
       v = T(pr.int)
       result = true
-  elif T is float:
-    if pr.kind == pkFloat:
-      v = pr.float
-      result = true
   elif T is seq[byte]:
     if pr.kind == pkByteString:
       v = pr.bytes
@@ -813,6 +809,10 @@ proc fromPreserve*[T, E](v: var T; pr: Preserve[E]): bool =
         if not result:
           v.setLen 0
           break
+  elif T is float32:
+    if pr.kind == pkFloat:
+      v = pr.float
+      result = true
   elif T is float64:
     case pr.kind
     of pkFloat:
@@ -821,6 +821,7 @@ proc fromPreserve*[T, E](v: var T; pr: Preserve[E]): bool =
     of pkDouble:
       v = pr.double
       result = true
+    else: discard
   elif T is Ordinal | SomeInteger:
     if pr.kind == pkSignedInteger:
       v = (T)pr.int
@@ -855,8 +856,9 @@ proc fromPreserve*[T, E](v: var T; pr: Preserve[E]): bool =
       if tupleLen(T) ==  pr.len:
         result = true
         for key, val in fieldPairs(v):
-          if result:
-            result = result and fromPreserve(val, pr[toSymbol(key, E)])
+          try: result = fromPreserve(val, pr[toSymbol(key, E)])
+          except KeyError: result = false
+          if not result: break
     else: discard
   elif T is ref:
     if isNil(v): new(v)
@@ -921,9 +923,21 @@ proc fromPreserve*[T, E](v: var T; pr: Preserve[E]): bool =
           # hopefully a `discard` of-branch, so discard `pr`
           result = true
         if result: break
-    else: result = fromPreserveHook(v, pr)
-  else: result = fromPreserveHook(v, pr)
-  # the hook doesn't compile but produces a useful error
+    else:
+      if pr.isDictionary:
+        result = true
+        var i: int
+        for key, _ in fieldPairs(v):
+          let val = pr.getOrDefault(toSymbol(key, E))
+          result = result and fieldFromPreserve(
+            key, v.dot(key), val)
+          if not result: break
+          inc i
+        result = result and (i == pr.len)
+  else:
+    result = fromPreserveHook(v, pr)
+      # a previous branch determined that the hook does not compile but
+      # calling it here explicitly produces a reasonable compiler error
   if not result:
     trace T, " !- ", pr
   else: