Make a variable unavailable in portion of codes

From time to time, I want, as a safety check, to check that a variable v is not used in some portion of code, or in the remainder of some function, even though it is still visible in the scope of this function/portion of code. For instance:

int x;
// do something with x 
DEACTIVATE(x);
// a portion of code which should not use x
ACTIVATE(x);
// do something else with x

Is there a good way to perform that type of verification at compile time?

NOTE: I know that one should always use a scope that is as small as possible for each variable, but there are cases where pushing this practice to an extreme can become cumbersome, and such a tool would be useful.

Thanks!开发者_高级运维

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The best way to achieve this is to actually have small scopes in your code, i.e. use short, focused methods which do one thing only. This way you tend to have few local variables per each individual method, and they go out of scope automatically once you don't need them.

If you have long legacy methods which make you worry about this problem, the best long-term solution is to refactor them by extracting smaller chunks of functionality into separate methods. Most modern IDEs have automated refactoring support which lowers the risk of introducing bugs with such changes - although the best is of course to have a proper set of unit tests to ensure you aren't breaking anything.

Recommended reading is Clean Code.

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Use

#define v @
..
#undef v

This should do it as @ is with very low probability conflicting with any other variable name or keyword or operator.

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As i know, no such compile verification. Maybe you can verify it by yourself using grep. I think the best way is to separate your function into two functions. One use the variable, and the other cannot see the variable. That's one of the reasons why we need functions.