Specify type of variable to allow tab completion

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.

[Walter Roberson]

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]

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"

Answer 1

[Adam Cooman]

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:

https://nl.mathworks.com/help/matlab/matlab_prog/function-argument-validation-1.html

Answer 2

[Chidvi Modala]

You can refer to Custom Code Suggestions and Completions

[Walter Roberson]

This only works while constructing the call to a function, to give hints as to what the proper arguments are for that function. This does not work while creating code for the function itself -- it does not give hints as to what valid class methods or class property names are while typing in the code that implements the class.

[Guillaume]

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]

@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]

@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.