Reason behind while (true) break

[ibrahimabtula]

I am looking at the ImapIdleExample and I cant understand the reason behind the following code

async Task FetchMessageSummariesAsync (bool print)
{
	IList<IMessageSummary> fetched = null;

	do {
		try {
			// fetch summary information for messages that we don't already have
			int startIndex = messages.Count;

			fetched = client.Inbox.Fetch (startIndex, -1, request, cancel.Token);
			break;
		} catch (ImapProtocolException) {
			// protocol exceptions often result in the client getting disconnected
			await ReconnectAsync ();
		} catch (IOException) {
			// I/O exceptions always result in the client getting disconnected
			await ReconnectAsync ();
		}
	} while (true);

	foreach (var message in fetched) {
		if (print)
			Console.WriteLine ("{0}: new message: {1}", client.Inbox, message.Envelope.Subject);
		messages.Add (message);
	}
}

I noticed it's like common pattern throughout the code.
While will be run only once to fetch and then break will break the loop.
Can't we fetch messages in a try catch without the while loop? What is the reason behind it ?

[jstedfast]

The while loop is there in case an exception occurs while trying to fetch.

[tjementum]

Controversial take, but this is one place where the goto command could be used to make it more clear that this is not a loop:

async Task FetchMessageSummariesAsync(bool print)
{
    IList<IMessageSummary> fetched = null;
    RetryFetch:
    try
    {
        // fetch summary information for messages that we don't already have
        int startIndex = messages.Count;

        fetched = client.Inbox.Fetch(startIndex, -1, request, cancel.Token);
    }
    catch (ImapProtocolException)
    {
        // protocol exceptions often result in the client getting disconnected
        await ReconnectAsync();
        goto RetryFetch;
    }
    catch (IOException)
    {
        // I/O exceptions always result in the client getting disconnected
        await ReconnectAsync();
        goto RetryFetch;
    }

    foreach (var message in fetched)
    {
        if (print)
            Console.WriteLine("{0}: new message: {1}", client.Inbox, message.Envelope.Subject);
        messages.Add(message);
    }
}

I'm not the only one thinking that this is sometimes better: https://www.youtube.com/watch?v=UPlESqDfsnQ.

[jstedfast]

I don't really find goto controversial myself, but yes, many people do which is why I shied away from it in example code.

You'll find examples of goto in MimeKit and MailKit's source code, but it's a "scary" concept to most .net developers (especially those who are just starting out).