3 files changed, 54 insertions, 6 deletions

diff --git a/src/new_fields/Doc.ts b/src/new_fields/Doc.ts
index 769c6aa73..59e61023f 100644
--- a/src/new_fields/Doc.ts
+++ b/src/new_fields/Doc.ts
@@ -10,14 +10,15 @@ import { RefField, FieldId } from "./RefField";
 import { ToScriptString, SelfProxy, Parent, OnUpdate, Self, HandleUpdate, Update, Id } from "./FieldSymbols";
 import { scriptingGlobal } from "../client/util/Scripting";
 import { List } from "./List";
+import { ComputedField } from "./ScriptField";
 
 export namespace Field {
     export function toKeyValueString(doc: Doc, key: string): string {
         const onDelegate = Object.keys(doc).includes(key);
 
-        let field = FieldValue(doc[key]);
+        let field = ComputedField.WithoutComputed(() => FieldValue(doc[key]));
         if (Field.IsField(field)) {
-            return (onDelegate ? "=" : "") + Field.toScriptString(field);
+            return (onDelegate ? "=" : "") + (field instanceof ComputedField ? `:=${field.script.originalScript}` : Field.toScriptString(field));
         }
         return "";
     }
diff --git a/src/new_fields/ScriptField.ts b/src/new_fields/ScriptField.ts
index e2994ed70..b5b1595cf 100644
--- a/src/new_fields/ScriptField.ts
+++ b/src/new_fields/ScriptField.ts
@@ -4,6 +4,7 @@ import { Copy, ToScriptString, Parent, SelfProxy } from "./FieldSymbols";
 import { serializable, createSimpleSchema, map, primitive, object, deserialize, PropSchema, custom, SKIP } from "serializr";
 import { Deserializable } from "../client/util/SerializationHelper";
 import { Doc } from "../new_fields/Doc";
+import { Plugins } from "./util";
 
 function optional(propSchema: PropSchema) {
     return custom(value => {
@@ -93,4 +94,30 @@ export class ComputedField extends ScriptField {
         }
         return undefined;
     }
+}
+
+export namespace ComputedField {
+    let useComputed = true;
+    export function DisableComputedFields() {
+        useComputed = false;
+    }
+
+    export function EnableComputedFields() {
+        useComputed = true;
+    }
+
+    export function WithoutComputed<T>(fn: () => T) {
+        DisableComputedFields();
+        try {
+            return fn();
+        } finally {
+            EnableComputedFields();
+        }
+    }
+
+    Plugins.addGetterPlugin((doc, _, value) => {
+        if (useComputed && value instanceof ComputedField) {
+            return { value: value.value(doc), shouldReturn: true };
+        }
+    });
 }
\ No newline at end of file
diff --git a/src/new_fields/util.ts b/src/new_fields/util.ts
index 47e467041..b59ec9b9a 100644
--- a/src/new_fields/util.ts
+++ b/src/new_fields/util.ts
@@ -1,5 +1,5 @@
 import { UndoManager } from "../client/util/UndoManager";
-import { Doc, Field } from "./Doc";
+import { Doc, Field, FieldResult } from "./Doc";
 import { SerializationHelper } from "../client/util/SerializationHelper";
 import { ProxyField } from "./Proxy";
 import { RefField } from "./RefField";
@@ -11,6 +11,20 @@ import { ComputedField } from "./ScriptField";
 function _readOnlySetter(): never {
     throw new Error("Documents can't be modified in read-only mode");
 }
+
+export interface GetterResult {
+    value: FieldResult;
+    shouldReturn: boolean;
+}
+export type GetterPlugin = (receiver: any, prop: string | number, currentValue: any) => GetterResult | undefined;
+const getterPlugins: GetterPlugin[] = [];
+
+export namespace Plugins {
+    export function addGetterPlugin(plugin: GetterPlugin) {
+        getterPlugins.push(plugin);
+    }
+}
+
 const _setterImpl = action(function (target: any, prop: string | symbol | number, value: any, receiver: any): boolean {
     //console.log("-set " + target[SelfProxy].title + "(" + target[SelfProxy][prop] + ")." + prop.toString() + " = " + value);
     if (SerializationHelper.IsSerializing()) {
@@ -85,12 +99,18 @@ export function getter(target: any, prop: string | symbol | number, receiver: an
 
 function getFieldImpl(target: any, prop: string | number, receiver: any, ignoreProto: boolean = false): any {
     receiver = receiver || target[SelfProxy];
-    const field = target.__fields[prop];
+    let field = target.__fields[prop];
     if (field instanceof ProxyField) {
         return field.value();
     }
-    if (field instanceof ComputedField) {
-        return field.value(receiver);
+    for (const plugin of getterPlugins) {
+        const res = plugin(receiver, prop, field);
+        if (res === undefined) continue;
+        if (res.shouldReturn) {
+            return res.value;
+        } else {
+            field = res.value;
+        }
     }
     if (field === undefined && !ignoreProto && prop !== "proto") {
         const proto = getFieldImpl(target, "proto", receiver, true);//TODO tfs: instead of receiver we could use target[SelfProxy]... I don't which semantics we want or if it really matters