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Specify type of variable to allow tab completion

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Adam Cooman
Adam Cooman on 5 Aug 2019
Answered: Adam Cooman on 30 Oct 2019
Is there a way to indicate the type of a variable to the static analysis tool in Matlab to allow tab completion when coding?
This could be usefull when passing objects as an argument to a function.

  2 Comments

Walter Roberson
Walter Roberson on 5 Aug 2019
Would this be for the purpose of text to display in a pop-up hint? Or is the idea that the tab completion would examine all of the variables that are in scope and only list for completion those that have particular data types?
Adam Cooman
Adam Cooman on 5 Aug 2019
Maybe I did not clearly word my question.
Assume that I have a class:
classdef MyClass
properties
property1
property2
property3
end
end
Now, I have a function which takes an object of this class as one of its inputs:
function MyFunction(input)
if ~isa(input,'MyClass')
error('wrong input type')
end
input.property1 = 5
end
Because the type of the "input" variable is unknown to the static analysis tool, I cannot use tab completion on the "input" variable. I would find it very usefull if tab completion would propose me a list of the different properties and functions that are available on "MyClass".
This works already when programming a dynamic method on a class.
When, for example, I add this simple function to "MyClass".
function res=DynamicMethod(obj)
obj.property1 = 5;
end
Matlab knows the type of the "obj" input variable, so it proposes the different properties and methods when typing "obj. + tab"

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Accepted Answer

Adam Cooman
Adam Cooman on 30 Oct 2019
Ken Atwell replied the question:
The new function argument validation allows to specify the type of function input variables. This will allow tab completion when writing the code.
This is new in Matlab 2019b and will cause syntax errors in any matlab version before 2019b.
More info here:

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More Answers (1)

Chidvi Modala
Chidvi Modala on 8 Aug 2019

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Guillaume
Guillaume on 8 Aug 2019
For that, the easiest is to construct a dummy object at the command prompt with the same name as the variable in the function.
So, at the command prompt create:
input = MyClass; %+ whatever arguments the constructor expects.
Then, you'll get tab completion when writing the function code (even though input shouldn't be in scope).
Bad variable name by the way, input is a matlab function. Plus it doesn't tell you anything about what's in the variable (other than it's the input to the function which the reader already knows).
Adam Cooman
Adam Cooman on 8 Aug 2019
@Chivdi and Walter: Indeed, I'm looking for tab completion during coding of the function itself, not for when I want to call the function afterwards.
I think it could be a usefull feature to use a syntax similar to property validation to function inputs. I noticed that tab completion works when I use a property which has a specified type in its validation.
@Guillaume: Thanks for the tip, creating a dummy object is indeed a solution, but a little bit of a hassle. (my bad variable name was just for this dummy example, just like the great property names "property1" "property2" and "property3")
Ken Atwell
Ken Atwell on 28 Oct 2019
@Adam: Exactly what you describe was added in R2019b -- see function argument validataion. Tab completion will use this information to try to make more targetted suggestions and completion.

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