Function argument validation and editor auto-completion in wrapper functions/classes

Question

Jan Kappen 2023-8-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2005567-function-argument-validation-and-editor-auto-completion-in-wrapper-functions-classes

评论： Jan Kappen 2023-8-22

TLDR;

Is it possible to automatically use the same argument validation + auto completion in wrapper functions as the called function, i.e. functions or method that just call an underlying function with the same arguments, using argument validation from the underlying function?

Longer version:

Suppose I have two classes, MeasurementDatastore and FileImporter.

FileImporter implements various ways to load data. Some key methods (which are not defined in an abstract interface, yet, but could be) are:

classdef FileImporter < handle
    properties (Dependent)
        ImportFcn function_handle = @(in)myFileImportFunction(in)
    end
    
    properties
        FilePaths (1,:) string {mustBeFile}
    end
    
    methods
        function out = loadData(obj)
            out = obj.ImportFcn();
            % throw error if data is empty etc
        end
        
        function addDataFiles(obj, filenames)
            arguments
                obj
                filenames (1,:) string {mustBeFile}
            end
            obj.FilePaths = [obj.FilePaths, filenames];
        end        
        
        function addDataFolder(obj, folders, opts)
            arguments
                obj
                folders (1,:) string {mustBeFolder}
                opts.Recursive logical = true;
                opts.Wildcard string
            end
            for folder = folders
                ... % search folders and files
                obj.addDataFiles(files);
            end
        end
    end
end

I.e., the class is used to first add folders or files and then load them using some custom importer fcn handle.

That class is now used in a higher level class MeasurementDatastore (quite simplificated example):

classdef MeasurementDatastore < handle
    properties
        LoadedData
        Loader FileLoader % should be an interface/abstract loader
    end
    
    methods
        function obj = MeasurementDatastore()
            obj.Loader = FileImporter() % instantiate FileImporter class
        end
        
        % just a wrapper method to the underlying FileImporter class
        function addDataFolder(obj, folders, opts)
            arguments
                % how to get the same argument validation + auto completion
                % as in FileImporter? 
            end
            obj.Loader.addDataFolder(folders, opts)
        end
    
        function loadData(obj)
            obj.LoadedData = obj.Loader.loadData() % calls FileImporter class
        end
    end
end

Of course, the MeasurementDatastore does more, transforms the data etc, that's why I need this additional layer.

The big question is: How can addDataFolder automatically use the same argument validations the referenced class FileImporter already has defined? Do I have to copy the block? I don't like that due to maintenance.

Can a meta class be used somehow?

I know, one can automatically get all properties auto completed and even validated against the property validation via

function obj = MeasDataHelper(propertyArgs)
    arguments
        propertyArgs.?MeasDataHelper
    end
end

which is pretty awesome. Is there a similar technique that can be used for simple wrapper/"forward" functions & methods?

Thanks!

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Answer 1

Karan Singh 2023-8-22

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https://ww2.mathworks.cn/matlabcentral/answers/2005567-function-argument-validation-and-editor-auto-completion-in-wrapper-functions-classes#answer_1291182

在 MATLAB Online 中打开

Hi Jan Kappen, it seems there is no other way than to just copy and paste the conditions for the required for argument validation and auto-completion. To achieve the same argument validation and auto-completion in the "addDataFolder" method of the "MeasurementDatastore" class as in the "FileImporter" class. We could modify the code as

        function addDataFolder(obj, folders, opts)
            arguments
                obj
                folders (1,:) string {mustBeFolder}
                opts.Recursive logical = true;
                opts.Wildcard string
            end
            
            obj.Loader.addDataFolder(folders, opts);
         end

In this modified code, the "addDataFolder" method in the "MeasurementDatastore" class includes the same argument validation as in the "FileImporter" class. By specifying the validation attributes {mustBeFolder}, {mustBeFile}, etc., you ensure that the input arguments meet the required criteria.

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Jan Kappen 2023-8-22

Hi @Karan Singh,

yes this is the obvious solution, I was hoping for something more automated. Are there other patterns to pass arguments a couple of methods down the class hierachy without lots of copy & paste?

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