CODEWITHSUNDEEP
if-statementbooleandart
Curyous
Curyous

Reputation: 8866

How do you use a return value of true in Dart?

I get the following error when I try to execute the code below.

Uncaught TypeError: Object true has no method 'dartObjectLocalStorage$getter'

I started a Web Application in Dart Editor Version 0.1.0.201201150611 Build 3331. Here is the complete code for the lone dart file. The if statement that results in the error is commented below.

#import('dart:html');

class Test3D {
  CanvasElement theCanvas;
  WebGLRenderingContext gl;

  static String vertexShaderSrc = """
    attribute vec3 aVertexPosition;

    void main(void) {
      gl_Position = vec4(aVertexPosition, 1.0); 
    }  
  """;

  Test3D() {
  }

  void run() {   
    write("Hello World!");

    // Set up canvas
    theCanvas = new Element.html("<canvas></canvas>");
    theCanvas.width = 100;
    theCanvas.height = 100;
    document.body.nodes.add(theCanvas);

    // Set up context
    gl = theCanvas.getContext("experimental-webgl");
    gl.clearColor(0.5, 0.5, 0.5, 1.0);
    gl.clear(WebGLRenderingContext.COLOR_BUFFER_BIT);

    WebGLShader vertexShader = gl.createShader(WebGLRenderingContext.VERTEX_SHADER);
    gl.shaderSource(vertexShader, vertexShaderSrc);
    gl.compileShader(vertexShader);

    // Adding this line results in the error: Uncaught TypeError: Object true has no method 'dartObjectLocalStorage$getter
    var wasSuccessful = gl.getShaderParameter(vertexShader, WebGLRenderingContext.COMPILE_STATUS);   
  }

  void write(String message) {
    // the HTML library defines a global "document" variable
    document.query('#status').innerHTML = message;
  }
}

void main() {
  new Test3D().run();
}

I'm really keen on dart and would appreciate any help you could give me on this.

Here is the console output for the error:

Uncaught TypeError: Object true has no method 'dartObjectLocalStorage$getter'
htmlimpl0a8e4b$LevelDom$Dart.wrapObject$member
htmlimpl0a8e4b$WebGLRenderingContextWrappingImplementation$Dart.getShaderParameter$member
htmlimpl0a8e4b$WebGLRenderingContextWrappingImplementation$Dart.getShaderParameter$named
unnamedb54266$Test3D$Dart.run$member
unnamedb54266$Test3D$Dart.run$named
unnamedb54266$main$member
RunEntry.isolate$current
isolate$Isolate.run
isolate$IsolateEvent.process
isolate$doOneEventLoopIteration
next
isolate$doRunEventLoop
isolate$runEventLoop
RunEntry
(anonymous function)

Upvotes: 1

Views: 744

Answers (2)

Florian Loitsch
Florian Loitsch

Reputation: 8128

The error indicates that somewhere in your code the field 'dartObjectLocalStorage' is accessed on the boolean true. The given code-snippet does not contain this identifier and is thus probably not responsible for the error. It could be that the error-reporting gives the wrong line number (potentially even the wrong file).

To debug this:

  • try to find a reference to 'dartObjectLocalStorage' in your code.
  • try to find a reference to 'dartObjectLocalStorage$getter' in the generated code.
  • run on the VM or compile with a different compiler (frogc vs dartc).

good luck.

Upvotes: 2

Lars Tackmann
Lars Tackmann

Reputation: 20865

According to the documentation for WebGLRenderingContext the return type is Object, if you know the object is bool you can just use it as a bool or dynamic

var v=gl.getShaderParameter(vertexShader, WebGLRenderingContext.COMPILE_STATUS)

or more explicitly

var v=gl.getShaderParameter(vertexShader, WebGLRenderingContext.COMPILE_STATUS).dynamic

and then use it in your conditional statement. Also try compiling it with frogc rather than the build in JavaScript compiler, it usually results in better errors.

Upvotes: 1

Related Questions