How to use static factory method?

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Vincent Schmidt
Vincent Schmidt 2021 年 7 月 13 日
回答済み: Greg 2024 年 5 月 13 日
I have following class definition under +mypackage\MyClass.m
classdef MyClass
properties
num
end
methods (Static)
function obj = with_five()
obj = MyClass(5);
end
end
methods
function obj = MyClass(num)
obj.num = num;
end
end
end
I use with_five() as a static factory method.
Following script should create two objects.
import mypackage.MyClass
class_test1 = MyClass(5);
class_test2 = MyClass.with_five();
class_test1 has been created.
For class_test2 it says:
Error using MyClass.with_five
Method 'with_five' is not defined for class 'MyClass' or is removed from MATLAB's search path.
Error in Testpackage (line 4)
class_test2 = MyClass.with_five();
When I put MyClass.m outside of a package folder and remove the "import" statement, it works.
What am I doing wrong?

回答 (1 件)

Greg
Greg 2024 年 5 月 13 日
Old question, but maybe others have seen this and wondered the same thing. Fairly simple answer.
In your factory method, you do not call out the namespace:
obj = MyClass(5);
Needs to be:
obj = mypackage.MyClass(5);
The import is in your test script, not your class. Import statements are extremely localized, so the factory method does not know about a MyClass, only a mypackage.MyClass.

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