Re: Exception handling
Rune Allnor wrote:
Hi all.
I have made a class for some data manipulation that tests for
data integrity before emarking on the processing. The class
contains a number of methods which test for certain error
conditions and throw exceptions if the errors are present
in the data.
Some of the errors, "annoying" errors, can be fixed automatically
when detected, and the routine can have another go at validating
the data before processing. Other errors, "serious" errors, have
to be piped on to the user to resolve.
The problem is: How does one implement this in C++?
The naive idea is easily expressed as:
try {
x->validate();
} catch (annoying) {
// repair whatever condition
try{ //<----- Recursive try-catch loop
x->validate(); //<-----
} //<-----
catch() {...} //<-----
}
catch(serious)
{
throw;
}
However, there can be any instances of any error condition,
so this is a recursive try-catch-repair-try-again algorithm
which is ridiculous to implement in the straight-forward way
as indicated above.
How should one implement this recursive try-catch structure?
Rune
I'm not sure if this is good enough but that's what I'd do anyway. First
you need to wrap up validate() to give better guarantee, like this:
void better_validate(T& x)
{
bool retry = true;
while (retry)
{
retry = false;
try{x->validate();}
catch (annoying)
{
retry = true;
restore_environment();
}
}
}
So in your user code you only have to deal with the serious exceptions:
Regards,
Ben
--
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]