From a string to function handle of a function handle
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Patrick Mboma
el 19 de Jul. de 2017
Comentada: James Tursa
el 20 de Jul. de 2017
Hi,
Is it possible to transform a string into a function handle calling another function handle?
More specifically, consider the following simple example
func1=@(x)mean(x)
tmp='@(x)func1(x)+3'
we know that defining
func2=str2func(tmp)
does not work.
Is there any way to create a function handle using tmp that will work?
Thanks
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James Tursa
el 19 de Jul. de 2017
func2 = eval(tmp);
2 comentarios
James Tursa
el 20 de Jul. de 2017
Yep, agreed. If you don't know where that string is coming from and what could be in it or don't trust the source, then eval should probably be avoided.
Más respuestas (1)
Walter Roberson
el 19 de Jul. de 2017
tmp='@(x)feval(evalin(''caller'',''func1''),x)+3'
2 comentarios
Walter Roberson
el 19 de Jul. de 2017
The basic issue is that str2func() is operating in a context outside your current workspace, so it does not have access to any variables in your workspace. evalin('caller') gives it that access. You would have the same difficulty with a plain variable:
>> A = 5
A =
5
>> tmp = '@(x) x+A'
tmp =
'@(x) x+A'
>> func2 = str2func(tmp)
func2 =
function_handle with value:
@(x)x+A
>> func2(7)
Undefined function or variable 'A'.
Error in @(x)x+A
str2func always does textual substitutions.
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