Re: Exception handling

From:
"James Kanze" <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Sun, 4 Mar 2007 06:25:53 CST
Message-ID:
<1173006972.415417.227590@j27g2000cwj.googlegroups.com>
Rune Allnor wrote:

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?


To begin with, it sounds to me like exceptions are the wrong
solution here. You expect to handle the error in the calling
function, so a return code would be generally more indicated.
Then, you just write a classical loop.

--
James Kanze (Gabi Software) email: james.kanze@gmail.com
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