Named arguments in Matlab?

Question

seth patterson ，2022-10-25

0
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Direct link to this question

https://ww2.mathworks.cn/matlabcentral/answers/1835238-named-arguments-in-matlab

回答： Chunru ，2022-10-26

I am digging through some old code that does named function arguments:

function self = Renderer(varargin)
            opt = varopts(varargin,...
                'scene','linuss', ...
                'renderer', 'iray', ...
                'host', 'localhost', ...
                'port', 24242, ...
                'samples', 100, 'render_iterate',4);

I'm wondering if matlab has a built in way to do this? Below is the helper function varopts... Can anyone explain what it's doing?

function [opt,xtra] = varopts(optlist, varargin)    
    [opt,xtra] = deal(struct());    
    
    % parse the field names and their default values
    for n=1:2:length(varargin)
        opt.((varargin{n})) = varargin{n+1};
    end    
    
    % I forget why I do this
    if numel(optlist) == 1 && iscell(optlist{1})
        optlist = optlist{1};
    end    
    
    % if an odd number of arguments is supplied, then
    % the first one is assumed to be a filename or structrure to 
    % supply default override values
    if mod(numel(optlist),2)                 
        opt = load_defaults(opt, optlist{1});        
        optlist = optlist(2:end);
    end
        
    % now apply any override values
    for n=1:2:length(optlist)
        if nargin == 1 || isfield(opt,optlist{n})
            opt.((optlist{n})) = optlist{n+1};
        else
            xtra.((optlist{n})) = optlist{n+1};
        end
    end
function opt = load_defaults(opt, defaults)
    if isstruct(defaults)
        % do nothing
    else        
        [~,~,ext] = fileparts(defaults);                
        if strcmp(ext, '.mat') || (strcmp(ext, '') && exist(defaults,'file') ~= 2)
            defaults = load(defaults);       
        elseif exist(defaults,'file') == 2 
            defaults = loadm(defaults);
        else
            error('varopts with odd number of arguments, expects first argument to be a config file');
        end
    end
    % now copy over the overrided values
    fields = fieldnames(opt);
    for n=1:length(fields)
        if isfield(defaults,fields{n})
            opt.(fields{n}) = defaults.(fields{n});
        end
    end
                        
function out = loadm(filename__)            
    run(filename__);    
    clear filename__;
    variables = who();        
    out = struct();
    for n=1:numel(variables)      
        out.(variables{n}) = eval(variables{n});
    end

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Cris LaPierre 2022-10-25

Perhaps this Answer is of interest

https://www.mathworks.com/matlabcentral/answers/497680-how-to-create-function-with-name-value-pair-arguments

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Answer 1

Chunru 2022-10-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1835238-named-arguments-in-matlab#answer_1083563

Use arguments block (additionaly for default value, type and size check. doc arguments for more details)

self = Renderer(samples = 200)
             scene: 'linuss'
          renderer: 'iray'
              host: 'localhost'
              port: 24242
           samples: 200
    render_iterate: 4
self = struct with fields:
             scene: 'linuss'
          renderer: 'iray'
              host: 'localhost'
              port: 24242
           samples: 200
    render_iterate: 4
function self = Renderer(opt)
    arguments
        opt.scene ='linuss'
        opt.renderer ='iray'
        opt.host ='localhost'
        opt.port = 24242
        opt.samples = 100
        opt.render_iterate = 4
    end
    % other operations based on opt
    disp(opt)
    self = opt;
end   