!7

set flag replaceACCInClassLoader_fullException.
set flag DynModule. // use central transpiler

cmodule StandardFunction {
  switchable S functionName;
  transient DynamicCallable f;
  transient Throwable error;
  
  start {
    dm_registerAs('standardFunctionHolder);
    onChange(r updateStatuses);
    loadFunction();
  }
  
  visual
    vstack(centerAndEastWithMargins(
      withLabel("Function:", dm_label('functionName)),
      jThreadedButton("Choose...", rEnter { dm_stringFieldDialog('functionName, onSet := rEnter newFunctionName) })));
      
  void newFunctionName() {
    setField(f := null);
    setField(error := null);
    loadFunction();
  }
  
  void updateStatuses {
    setModuleName(
      empty(functionName) ? "Standard function as module"
      : "Function " + functionName + " - "
      + (hasError() ? "Error" : loaded() ? "loaded" : "not loaded"));
  }
  
  void loadFunction() q {
    try {
      setField(f := methodAsDynamicCallable(loadFunctions_cached(functionName), functionName));
    } catch e {
      setFields(f := null, error := e);
    }
  }
  
  // API
  
  S functionName() { ret functionName; }
  
  O callTheFunction(O... args) {
    while (f == null && error == null) sleep(10);
    if (error != null) throw rethrow(error);
    ret callF(f, args);
  }
  
  bool loaded() { ret f != null; }
  bool hasError() { ret error != null; }
}