How to refactor try..catch

Question

4.50/5 (2 votes)

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I have following code snippet:

C#

private void DoSomething1()
        {
            try
            {
                Method1();
            }
            catch (Exception ex)
            {
                ProcessException(ex);
            }
        }

        private void DoSomething2()
        {
            try
            {
                Method2();
            }
            catch (Exception ex)
            {
                ProcessException(ex);
            }
        }

I would like to prevent try catch block to be duplicated. I remember it can be writen by using Lambda expressions. How to do it better?

Posted 23-Mar-11 1:43am

Pavel Yermalovich

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Pavel Yermalovich · Answer 1 · 2011-03-23T03:29:00

Solution 2

One my friend offered to write in this manner:

C#

private void PackExceptionHandling(Action f)
        {
            try
            {
                f();
            }
            catch (Exception ex)
            {
                ProcessException(ex);
            }
        }

Then let's call methods where we want to catch an exception:

C#

...
PackExceptionHandling(Method1);
PackExceptionHandling(Method2);
...

Looks very good.

Posted 23-Mar-11 3:29am

Pavel Yermalovich

Comments

BobJanova 23-Mar-11 9:56am

This is good as long as the code is not in a performance critical point in the app (delegate/action references do increase the overhead by a small amount).

Also, although you excellently answer the specific question asked by the OP, it is not great style to use a delegate simply to pack the exception handling. I suspect the original questioner may have a slightly higher level design issue as suggested by Mika below.

Sergey Alexandrovich Kryukov 23-Mar-11 18:02pm

You should not catch Exception. Generally you should catch derived classes. See my Answer.
--SA

#realJSOP · Answer 2 · 2011-03-23T03:42:00

Solution 3

You could use a delegate. Set the delegate, and call a method that calls the delegate. As long as the method prototypes match, this should be a viable approach. I've used it and it works a treat.

Oops, looks like using Action is the same thing.

Posted 23-Mar-11 3:42am

#realJSOP

Updated 23-Mar-11 3:43am

v2

Wendelius · Answer 3 · 2011-03-23T01:47:00

Solution 1

Why not use single method with parameterization? Another possibility could be to move the try catch to the calling layer...

Posted 23-Mar-11 1:47am

Wendelius

Comments

Pavel Yermalovich 23-Mar-11 8:06am

How? I forgot how to do it

Wendelius 23-Mar-11 8:18am

You're most like referring lambdas, but what I meant is that could you either:
DoSomething(int execNumber) {
try {
if (execNumber == 1) Method1();
if (execNumber == 2) Method2();
...

or

SomeMethod() {
try {
if (decision to call DoSomething1) DoSomething1();
else DoSomething2();
...

Or are these method totally unrelated?

Sergey Alexandrovich Kryukov · Answer 4 · 2011-03-23T12:00:00

The code in your sample usually makes no sense. What, you block propagation of exception up the stack? Usually, this is wrong. If you understand your exception handling strategy, the "reuse" problem will not appear at all. The common problem is using "try" to often, where you should simply let go and catch is much upper on stack.

Please read my directions here:
How do i make a loop that will stop when a scrollbar reaches the bottom[^]
When i run an application an exception is caught how to handle this?[^]

—SA