callback within the class?
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hi, i got the following class:
classdef form<handle
properties
type = 'square'
b
h
A
Iy
Iz
Wy
Wz
end %properties
events
calc
end %events
methods
function f = form(b,h)
f.b=b;
f.h=h;
f.update()
end
function obj = update(obj)
obj.A= obj.h*obj.b;
obj.Iy= obj.h^3*obj.b/12;
obj.Iz= obj.b^3*obj.h/12;
obj.Wy= obj.h^2*obj.b/6;
obj.Wz= obj.b^2*obj.h/6;
end
end % events
end%class
how do i manage to call the function update everytime when either form.a or form.h of an instance is changed withoud adding a listener to the instance? is there a way to directly built thin in the class definition?
thanks a lot for help
采纳的回答
Daniel Shub
2012-3-14
It seems like all the properties other than b and h should be dependent. This would allow you to get rid of the update method. If you really want to go the update route, you could write a set method for b and h which will call the update method.
Does the following work for you?
classdef form<handle
properties
type = 'square'
b
h
end
properties (Dependent)
A
Iy
Iz
Wy
Wz
end %properties
methods
function f = form(b,h)
f.b=b;
f.h=h;
end
function val = get.A(obj)
val= obj.h*obj.b;
end
function val = get.Iy(obj)
val= obj.h^3*obj.b/12;
end
function val = get.Iz(obj)
val= obj.b^3*obj.h/12;
end
function val = get.Wy(obj)
val= obj.h^2*obj.b/6;
end
function val = get.Wz(obj)
val = obj.b^2*obj.h/6;
end
end % events
end%class
You could also go with the "ugly" update method:
classdef form<handle
properties
type = 'square'
b
h
A
Iy
Iz
Wy
Wz
end %properties
methods
function f = form(b,h)
f.b=b;
f.h=h;
end
function set.b(obj, val)
obj.b = val;
obj.update;
end
function set.h(obj, val)
obj.h = val;
obj.update;
end
function obj = update(obj)
obj.A= obj.h*obj.b;
obj.Iy= obj.h^3*obj.b/12;
obj.Iz= obj.b^3*obj.h/12;
obj.Wy= obj.h^2*obj.b/6;
obj.Wz= obj.b^2*obj.h/6;
end
end % events
end%class
更多回答（1 个）
Walter Roberson
2012-3-14
0 个投票
You do not appear to have a form.a . You do have a form.A which is overwritten in update() . If update() is to be called as a callback when form.A is changed, then it would be called when form.A is changed within update()
What is the point of having an update when form.A is changed, if the value of form.A is going to be ignored?
Is it perhaps form.b you wish to trigger update() on?
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