Add onRetract sugar to scope of onPublish

src/syndicate.nim

@@ -3,7 +3,7 @@
 
 import std/macros
 import preserves
-import syndicate/[actors, patterns]
+import syndicate/[actors, dataspaces, patterns]
 export patterns
 
 proc wrapPublishHandler(handler: NimNode): NimNode =
@@ -30,15 +30,20 @@ proc wrapPublishHandler(handler: NimNode): NimNode =
   var
     varSectionOuter = newNimNode(nnkVarSection, handler).add(
       newIdentDefs(valuesSym, valuesTuple))
-    body = newStmtList(varSectionInner, handler[6])
+    publishBody = newStmtList(varSectionInner, handler[6])
     turnSym = ident"turn"
     handleSym = ident"handle"
     handlerSym = genSym(nskProc, "publish")
+    onRetractIdent = ident"onRetract"
   quote do:
-    proc `handlerSym`(_: Entity; `turnSym`: var Turn; bindings: Assertion; `handleSym`: Handle) =
+    proc `handlerSym`(entity: Entity; `turnSym`: var Turn; bindings: Assertion; `handleSym`: Handle) =
       `varSectionOuter`
       if fromPreserve(`valuesSym`, bindings):
-        `body`
+        template `onRetractIdent`(retractBody: untyped): untyped =
+          proc callback(e: Entity; turn: var Turn; h: Handle) =
+            retractBody
+          entity.retractImpl = callback # TODO: fine to clobber previous callback?
+        `publishBody`
 
 proc wrapMessageHandler(handler: NimNode): NimNode =
   handler.expectKind nnkDo

tests/chat.nim

@@ -10,17 +10,9 @@ from syndicate/protocols/protocol import Handle
 
 from os import getCurrentProcessId
 
-when defined(linux):
-  proc getentropy(buf: pointer; bufLen: csize_t): cint {.
-    importc, header: "sys/random.h".}
-
 proc mint(): SturdyRef =
-
-  #var key: array[32, byte]
-  #doAssert getEntropy(addr key[0], csize_t key.len) == 0
-  #mint(key, "syndicate")
-  let pr = parsePreserves("""<ref "syndicate" [] #x"a6480df5306611ddd0d3882b546e1977">""", Ref)
-  doAssert fromPreserve(result, pr)
+  var key: array[16, byte]
+  mint(key, "syndicate")
 
 waitFor runActor("chat") do (turn: var Turn):
 
@@ -40,12 +32,12 @@ waitFor runActor("chat") do (turn: var Turn):
 
     updateUsername(turn, "user" & $getCurrentProcessId())
 
-    onPublish(turn, ds, Present ? {0: `?`()}) do (username: string):
+    onPublish(turn, ds, Present ? {0: `?*`()}) do (username: string):
       echo username, " arrived"
-      #onRetract:
-      #  echo username, " left"
+      onRetract:
+        echo username, " left"
 
-    onMessage(turn, ds, Says ? {0: `?`(), 1: `?`()}) do (who: string; what: string):
+    onMessage(turn, ds, Says ? {0: `?*`(), 1: `?*`()}) do (who: string; what: string):
       echo who, ": ", what
 
     message(turn, ds, Says(who: username, what: "hello"))