Reiterating a Try statement using GoTo in the Catch clause?

Question

I am examining some code examples and have seen similar variation to the following examples, one of them made me very curious.

When a goto_tag is placed before a try statement. This makes complete sense and it just runs through the try again.

retry_tag: //the goto tag to re-attempt to copy a file

try {
    fileInfo.CopyTo( toAbsolutePath + fileInfo.Name, true ); //THIS LINE MIGHT FAIL IF BUSY
} catch {
    Thread.Sleep(500); //wait a little time for file to become available.
    goto retry_tag; //go back and re-attempt to copy
}

However, as the following was presented to me I did not understand it. When a goto_tag is placed within the try statement, and is called from within the catch block.

try {
    retry_tag: //the goto tag to re-attempt to copy a file

    fileInfo.CopyTo( toAbsolutePath + fileInfo.Name, true ); //THIS LINE MIGHT FAIL IF BUSY
} catch {
    Thread.Sleep(500); //wait a little time for file to become available.
    goto retry_tag; //go back and re-attempt to copy
}

Is the try block resurrected? Or are the two examples functionally identical, or is this an completely illegal operation and won't even compile?

This is all purely out of curiosity, and of course I would prefer the first example, if either of them..

Thanks for any insight!!

Do not use goto! Just use a loop. See: https://stackoverflow.com/q/11906056/6400526, or: https://stackoverflow.com/q/46586/6400526 — Gilad Green, Apr 05 '19 at 13:18
Use some loop instead, e.g. `while`. And don´t catch exceptions that you can avoid in the first place. — MakePeaceGreatAgain, Apr 05 '19 at 13:19

score 2 · Accepted Answer · answered Apr 05 '19 at 13:29

2

To actually answer your question:

No, these are not the same.

The first example will compile; the second is illegal.

(The matter of whether you should write code like this is a different question... and off course, you should not if you can help it.)

answered Apr 05 '19 at 13:29

Matthew Watson

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I am unfamiliar with the `goto` and do not use it typically. I shall adhere to your words of wisdom and avoid patterns such as these. Thanks! – Logic1 Apr 05 '19 at 13:43

score 1 · Answer 2 · answered Apr 05 '19 at 13:20

1

You can implement a simple while instead of goto:

// loop until ... 
while (true) {
  try {
    fileInfo.CopyTo(Path.Combine(toAbsolutePath, fileInfo.Name), true); 

    // ... file copied
    break;
  } 
  catch (IOException) {
    Thread.Sleep(500); //wait a little time for file to become available.       
  } 
}

answered Apr 05 '19 at 13:20

Dmitry Bychenko

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I am correcting the `goto` example mentioned previously in favor of this. Thank you – Logic1 Apr 05 '19 at 13:45

Reiterating a Try statement using GoTo in the Catch clause?

2 Answers2