Comparison with False - something I don't understand

[Tim Harig]

On 2010-12-02, Paul Rubin <no.email at nospam.invalid> wrote:
> Tim Harig <usernet at ilthio.net> writes:
>>> longjmp.  Alternatively you can have an auxiliary stack of cleanup
>>> records that the longjmp handler walks through.  Of course if you do
>>
>> Only if you already have pointers to *all* of the data structures at
>> the point where you put your setjmp().
>
> The setjmp point only has to know where the aux stack is and its depth
> when the longjmp happens.  The cleanup records contain any necessary
> pointers to data structures that need freeing.  That is basically how
> try/finally would do it too.  This is pretty standard stuff.

I am not talking about what setjmp() has to do, I am talking about what
*you* have to do after setjmp() returns.  If you have allocated memory in
intermediate functions and you don't have a reference to them outside of
the functions that longjmp() bypasses from returning properly (and thus
either not clearning data structures or returning a reference to those data
structures as it normally would) then you have potential memory leaks,
dangling pointers, etc.

I am not saying that this cannot be done.  What I am saying is that it
is inherently error prone.