What is your preferred way to clean a while loop like this?

Question

I'm a bit OCD about my code and wondered how other people structure the following sample control flow. I haven't found anything that passes my "pretty" code test.

var records = repo.GetRecords(batch:10);

while(records.Any())
{
    var processed = ProcessRecords(records);        
    repo.DeleteRecords(processed);      
    records = repo.GetRecords(batch:10);
}

Thanks

isn't it (deleting elements onne by one) slower than a counter? — fatihk, Apr 12 '13 at 18:21
@ChuckConway Nothing more than aesthetics I guess. Thinking maybe someone had a clever lambda approach. — NATO24, Apr 12 '13 at 21:36

John Kugelman · Answer 1 · 2013-04-12T18:40:04.983

1

while (true)
{
    var records = repo.GetRecords(batch:10);

    if (!records.Any())
        break;

    var processed = ProcessRecords(records);        
    repo.DeleteRecords(processed);      
}

edited Apr 12 '13 at 18:40

answered Apr 12 '13 at 18:20

John Kugelman

349,597
67
533
578

I normally do it the way you mentioned but I even add a delay before breaking. Would that be a bad idea? – Vaibhav Desai Apr 12 '13 at 18:23
@VaibhavDesai What do you mean you add a delay before breaking? – John Kugelman Apr 12 '13 at 18:24
Just a sleep for say 10 seconds to avoid checking again and again if there is nothing to process. I guess this would be an app specific thing. – Vaibhav Desai Apr 12 '13 at 18:31
1

This method feels like a kludge. For loops are typically used when you have a known beginning and ending. – Chuck Conway Apr 12 '13 at 18:32
1

how is this any cleaner, neater or whatever than the original? I see a `for (;;)` I'll just be wondering wtf? – Filip Apr 12 '13 at 18:37
@ChuckConway `for (;;)` is the way I write infinite loops. It's equivalent to `while (true)`. The difference is just a matter of style. Six of one, half a dozen of the other. – John Kugelman Apr 12 '13 at 18:39

score 1 · Accepted Answer · edited May 23 '17 at 11:49

Similar to @John Kugleman's above, but using while rather than for.

while (true)
{
    var records = repo.GetRecords(batch:10);

    if (!records.Any()) break;

    var processed = ProcessRecords(records);        
    repo.DeleteRecords(processed);      
}

You can also find questions like this:

Split List into Sublists with LINQ

That ask how to "chunkify" a sequence of items. That technique might or might not apply to your situation.

Assuming a Chunk extension method (similar to @TickleMeElmo's answer or Split from @JaredPar's answer), your code might look like this:

foreach (var chunk in repo.GetRecords().Chunk(10))
{
  var processed = ProcessRecords(chunk);
  repo.DeleteRecords(processed);
}

This idiom might not work that well if you already have some sort of "chunkification" built into to your repository.

What is your preferred way to clean a while loop like this?

2 Answers2