nargout with class method handles

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Markus Leuthold
Markus Leuthold 2015-4-22
回答： Guillaume 2015-4-22
Assume you have the following class
classdef MyClass
methods
function fcn(~)
end
end
end
The following call of nargout
c=MyClass;
nargout(@c.fcn)
always returns -1, no matter how many output arguments the function has. Why is that?
I'm aware this already has been discussed here, but the proposed workaround
nargout('MyClass>MyClass.fcn')
is not suitable if you only know the function handle. The provided answer is already 5 years old, is there an update on this shortcoming?

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回答（1 个）

Guillaume
Guillaume 2015-4-22
With no guarantee that it works in all cases, this may be a workaround (not a pretty one):
function nout = nargout_for_class_fhandle(fhandle)
finfo = functions(fhandle);
fwspace = finfo.workspace{1};
wspacefields = fieldnames(fwspace);
mc = metaclass(fwspace.(wspacefields{1}));
searchnames = cellfun(@(name) sprintf('%s//.%s', wspacefields{1}, name), {mc.MethodList.Name}, 'UniformOutput', false);
midx = find(regexp(finfo.function, searchnames, 'once'));
mm = mc.MethodList(midx);
nout = numel(mm.OutputNames);
end
I've not put any error checking in there and because it attempts to find the method name in the body of the anonymous function code it could be defeated.

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