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.NET Forum / Languages / C# / March 2008break out of if
it seems a shame you can not do this: if (blah) { if (blob) break; }//if i know it seems like you can do if (blah && !blob) { }//if but what if you want to do this: if (blah) { bunch of code if (blob1) break; bunch of code if (blob2) break; bunch of code if (blob3) break; bunch of code if (blob4) break; bunch of code }//if without break you have to if (blah) { bunch of code if (!blob1) { bunch of code if (!blob2) { bunch of code if (!blob3) { bunch of code if (!blob4) { bunch of code }//if }//if }//if }//if }//if or you can put the code into a method and use return if (blah) syntaxworkaround(); void syntaxworkaround() { bunch of code if (blob1) return; bunch of code if (blob2) return; bunch of code if (blob3) return; bunch of code if (blob4) return; }//method but what if there are 20 local variables that you are using? now you have to pass them all or create a new argument class for them or move them up to class scope but that might not be sensible why not just implement break for all blocks ? using (something) { if (problem) break; }//using and on that subject why not have multiple breaks? while (true) { while (true) { if (fedup) break(2); }//while }//while breaks out of two enclosing blocks if there is amiguity between break out of loop or break out of block maybe use a different keyword "leave" or something so it is always clear which class of block you wish to exit why? that's what I want to know ... > why not just implement break for all blocks ? That would change the meaning of an existing "break" used validly to break from a loop. > why not have multiple breaks? [example: break(2)] That would be very susceptible to introducing bugs when innocently adding an extra nest level... you'd need some kind of named break point, but then you're back at "goto considered harmful" > why? that's what I want to know ... Most of the time it isn't an issue... break etc are mainly useful to exit loops; as you say, for regular logic you can always refactor into a method, and the IDE can do most of this for you by selecting the block you want to move (i.e. it should handle the args etc). If you *really* want, you could semi-refactor it in-place using a delegate; this will /essentially/ use captured variables to do something like the "new argument class" idea you mentioned, but keeps the code in-place; slightly more expensive, though. MethodInvoker someCode = delegate { // foo if(blob1) return; // bar if(blob2) return; // blip }; someCode(); // exec Marc <snip> > If you *really* want, you could semi-refactor it in-place using a delegate; > this will /essentially/ use captured variables to do something like the "new [quoted text clipped - 9 lines] > }; > someCode(); // exec My eyes! My eyes! (And yes, that's after pointing out the availability of goto.)  SignatureJon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet World class .NET training in the UK: http://iterativetraining.co.uk lol; we'll have to host an "ugliest trivial code" compo some time ;-p I never said it was great, just that it would technically work... For myself, it'd be: right-click, refactor, extract method, [fix up any oddities], move on. Marc > lol; we'll have to host an "ugliest trivial code" compo some time ;-p Tonight? :) > I never said it was great, just that it would technically work... Sounds like the motto for the ugliest code competition. > For myself, it'd be: right-click, refactor, extract method, [fix up any > oddities], move on. :) SignatureJon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet World class .NET training in the UK: http://iterativetraining.co.uk Nah, if there are any perl devs they'll win hands down... ;-p > <snip> > [quoted text clipped - 18 lines] > Jon Skeet - <sk...@pobox.com>http://www.pobox.com/~skeet Blog:http://www.msmvps.com/jon.skeet > World class .NET training in the UK:http://iterativetraining.co.uk hey, My opinion is that IF it does exist is for a reason and you can use it where it makes sense. That said, I have never used it :) <snip> > why? that's what I want to know ... Well, there's always "goto" if you really want it: using System; public class Test { static void Main() { int i = 5; int j = 10; if (i==5) { if (j==10) { goto done; } Console.WriteLine("Oo!"); } done: Console.WriteLine("Done"); } } However, I'd suggest that if you get into that kind of situation (with 20 local variables and nesting 6 levels deep) then you'd be a lot better off refactoring into smaller methods anyway. SignatureJon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet World class .NET training in the UK: http://iterativetraining.co.uk > it seems a shame you can not do this: > [quoted text clipped - 92 lines] > > why? that's what I want to know ... You can use return instead, refactor that piece of code in a method alone. You can refactor each of the pieces of code in a separated methods. Or you can wrap the entire thing in a while(true) , then you can use break; as y ou want, just make sure to put a break at the end of the piece of code. thanks for your thoughts i learnt a thing or three Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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