How to make a function like eval ?

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Arnaud
Arnaud 2014-8-13
编辑： Arnaud 2014-8-13
Hello,
I need a modified eval function. For example, I have in my workspace :
Nx = 3;
mystring = '1+2*Nx';
is_string = false; % treat it as matlab code
is_string2 = true; % treat it as text
I want to run the following lines :
if is_string, out = mystring,
else out = eval(mystring),
end
if is_string2, out2 = mystring,
else out2 = eval(mystring),
end
I am looking for a way to put this in a function :
Nx = 3;
mystring = '1+2*Nx'
is_string = false; % treat it as matlab code
is_string2 = true; % treat it as text
out = my_eval(mystring,is_string) % returns 7
out2 =my_eval(mystring,is_string2) % returns '1+2*Nx'
Anybody knows how to do this ?
Thanks

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采纳的回答

dpb
dpb 2014-8-13
function out=my_eval(in,isStr)
if isStr
out=in;
else
out=evalin('caller',in);
end
doc evalin % for details/limitations
Might also consider using function handles and, perhaps creating dynamically an anonymous function handle which is then evaluted...depends on the end use.
  1 个评论
Arnaud
Arnaud 2014-8-13
Thanks ! Obviously I should have looked at the end of the eval function to find this evalin function !

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更多回答（1 个）

Adam
Adam 2014-8-13
I would define as follows:
Nx = 3;
myFunc = @() 1 + 2*Nx
then
out = my_eval( myFunc, is_string )
would contain something like:
if is_string
out = strrep( func2str( myFunc ), '@()', '' )
else
out = myFunc();
end

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