Problem with properties in App Designer.

New
2017 7 28
1 个回答
更新时间：2017 7 29
11 次查看（30 天）

0 个投票

Hello. I need help with "properties" in App Designer. I have some trouble with realization the method of symmetrical components.
properties (Access = public)
a = -.5 + sqrt (3) / 2 * j; % Phase-shift operator
     F = [1 a^2 a; 1 a a^2; 1 1 1]; % Matrix Fortescue
end
Message: "Invalid default value for property 'F' in class 'App1': Undefined function or variable 'a'."
If I replace "a" with "app.a" in the Matrix Fortescue.
Message: "Invalid default value for property 'F' in class 'App1': Undefined variable "app" or class "app.a"."

请先登录，再回答此问题。

回答（1 个）

Steven Lord
Steven Lord 2017-7-28

0 个投票

Since you're probably not going to want a and F to change based on the state of your app, make them Constant properties, properties with the Constant attribute.

6 个评论
显示 4更早的评论 隐藏 4更早的评论

New
New 2017-7-28
properties (Constant)
a = 1;
b = a+1;
end
function ButtonPushed(app, event)
app.EditField.Value = app.EditField.Value + app.b;
end
Message: Invalid default value for property 'b' in class 'App1': Undefined function or variable 'a'.
Steven Lord
Steven Lord 2017-7-29
You want to define the property app.b in terms of the property app.a, not a variable a. In the first example on the documentation page to which I directed you, note how property NamedConst.D is defined in terms of property NamedConst.R and not on a variable named R.
New
New 2017-7-29
编辑：New 2017-7-29
1 example: Invalid default value for property 'F' in class 'App1': Undefined variable "app" or class "app.a".
properties (Access = public)
a = -.5 + sqrt (3) / 2 * j; % Phase-shift operator
F = [1 app.a^2 app.a; 1 app.a app.a^2; 1 1 1]; % Matrix Fortescue
end
2 examle: Just replace 'app.a' with value 'a' in 'F'.
properties (Access = public)
a = -.5 + sqrt (3) / 2 * j;
F = [1 (-.5 + sqrt (3) / 2 * j)^2 -.5 + sqrt (3) / 2 * j; 1 -.5 + sqrt (3) / 2 * j (-.5 + sqrt (3) / 2 * j)^2; 1 1 1];
end
3 example: Add startup function.
properties (Access = public)
a = -.5 + sqrt (3) / 2 * j;
F;
end
...
function startupFcn(app)
app.F = [1 app.a^2 app.a; 1 app.a app.a^2; 1 1 1];
end
2 and 3 example work true. But how define property on other properties in the first case? And what difference between 3 and 1 case?
Steven Lord
Steven Lord 2017-7-29
The name of your app class is App1? Then you need App1.a. In general if your app class was named CLASSNAME, you would use CLASSNAME.a.
New
New 2017-7-29
编辑：New 2017-7-29
No, prefix does not depend on the name of the application or classname.
Steven Lord
Steven Lord 2017-7-29
That is correct IF you're referring to a property of an instance of the class. A Constant property can be accessed even if you don't have an instance of the class, and the way you do that is by using the name of the class.

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Creating, Deleting, and Querying Graphics Objects 的更多信息

标签

提问:

New
New
2017-7-28

评论：

Steven Lord
Steven Lord
2017-7-29

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by