Possible to create a function where the input is changed?

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Josh
Josh 2012-2-10
编辑： Erik 2013-10-8
I understand it is one of the "cardinal rules" of MATLAB that functions do not affect the input values (versus scripts that do); however, is it possible to create a function where this is violated?
For example:
>>x = 10
>>Function(x)
%Running this would change the value of x in the workspace to some other value

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采纳的回答

Sean de Wolski
Sean de Wolski 2012-2-10
doc assignin
doc evalin
Why would you want to do this?
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Josh
Josh 2012-2-10
It was more a bet of whether or not you can or cannot do it. I'll be sure to try and figure it out using that documentation; worst case scenario I'll use Matt's idea.
Josh
Josh 2012-2-13
Was able to create a function to do just this using assignin, thank you!

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更多回答（2 个）

Matt Tearle
Matt Tearle 2012-2-10
I am not doing this...
classdef passbyref < handle
properties
value
end
methods
function x = passbyref(y)
x.value = y;
end
function notagreatidea(x)
x.value = x.value + 1;
end
end
end
And then
>> x = passbyref(42)
>> notagreatidea(x)
>> x
May Cleve have mercy on my soul.
Also: what Sean and Walter said.
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Matt Tearle
Matt Tearle 2012-2-10
I'll let you argue the semantics with your bet opponent, but notagreatidea is kindasorta a function -- it's actually a method of the passbyref class. So it only works on passbyref objects. However, once you have a passbyref object (x = passbyref(42)), it is a single "function call" that invokes the notagreatidea method and changes its value property.
For the sake of your bet, follow Sean's first link... [hint]
Josh
Josh 2012-2-13
Thanks for the help, but went with Sean's answer for simplicity's sake.

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Walter Roberson
Walter Roberson 2012-2-10
Yes, it is possible. There are not many cases where it is a good idea, however.

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