如何验证函数句柄作为输入参数? [英] How can I validate a function handle as an input argument?

问题描述

我有一个具有函数句柄的类作为其properties之一.

I have a class that has a function handle as one of its properties.

classdef MyClass
    properties
        hfun %function handle 
    end

    methods
        function obj = Myclass(hfun,...)
            %PROBLEM: validate that the input argument hfun is the right kind of function
            if ~isa(hfun,'function_handle') || nargin(hfun)~=1 || nargout(hfun)~=1
                error('hfun must be a function handle with 1 input and 1 output');
            end
            obj.hfun = hfun;
        end
    end
end

我想确保输入参数hfun是具有1个输入和1个输出的函数句柄，否则它将出错.如果我可以更具体一些，我希望此函数将Nx3数组作为输入参数，并返回Nx3数组作为输出参数.

I'd like to make sure that the input argument hfun is a function handle with 1 input and 1 output, otherwise it should error. If I could get even more specific I'd like this function to take an Nx3 array as an input argument and return an Nx3 array as the output argument.

以上代码适用于f = @sqrt之类的内置函数，但是如果我尝试放入诸如f = @(x) x^(0.5)之类的匿名函数，则nargout(hfun)为-1，因为它将匿名函数视为[varargout] = f(x).此外，如果将句柄输入到f = @obj.methodFun之类的类方法，则它将把函数转换为[varargout] = f(varargin)形式，对于nargin和nargout都返回-1.

The above code works for built-in functions like f = @sqrt but if I try to put in an anonymous function like f = @(x) x^(0.5), then nargout(hfun) is -1 because it treats anonymous functions as [varargout] = f(x). Furthermore if you input the handle to a class method like f = @obj.methodFun, then it converts the function to the form [varargout] = f(varargin) which returns -1 for both nargin and nargout.

有人能找到一种简便的方法来验证函数句柄作为输入参数吗?与它来自哪种函数无关?

Has anyone figured out a convenient way to validate a function handle as an input argument? Independent of what kind of function handle it's from?

推荐答案

最接近验证函数句柄的输入和输出的地方是try/catch语句.

The closest I've come to validating the inputs and outputs of a function handle is inside a try/catch statement.

function bool = validateFunctionHandle(fn)
    %pass an example input into the function
    in = blahBlah; %exampleInput
    try
        out = fn(in);
    catch err
        err
        bool = false;
        return;
    end

    %check the output argument
    if size(out)==correctSize and class(out)==correctType
        bool=true;
    else
        bool=false;
    end
end

这篇关于如何验证函数句柄作为输入参数?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！