On Sep 6, 2009, at 5:09 PM, Pierre Morcello wrote:
What is a "break-scope problem" to you? I think you might use the wrong "analysis pattern" here...
I was reusing the same kind of words than the previous comment of Stefan Strasser, to answer clearly to his remarks. Sorry if it made things less clear: He wrote "if you need a construct that forms a scope, accomplishes a tasks and then exists the scope from anywhere in between, that's a function.". He was presenting things like a problem and its solution.
I have never heard of 'analysis pattern', only 'design patterns' and 'idioms'. I will look at this.
Anyway just let compare 2 sample codes:
Of course people can already write : if(!filestream.bad()) { if(!filestream.good()) { if(xmlLoadFrom(filestream)) { // and so on, to test if the xml is valid, etc... }else{ log("the file is no xml document."); } }else{ log("error inside the file (eof)"); } }else{ log("error at opening file"); }
and :
Breakable { if(!filestream.bad()) { log("error at opening file"); break; }
if(!filestream.good()) { log("error inside the file (eof)"); break; }
if(!xmlLoadFrom(filestream)) { log("the file is no xml document."); break; }
// and so on, to test if the xml is valid, etc... }
Have a deep breath, compare, and then tell me which is more readable. Which is the easier to maintain? If another test is to be added, which version will be the simpliest to modify?
For these 3 reasons, I prefer the second one.
If you think this usage might lead to problems, could you explain which ones ?
This is the typical use, that of exceptional cases. Luckily, what is exceptional at one level can be totally tolerable at a higher (and invoking and/or embedding...) level, thus we can use a try-catch construct and throw an exception. I am not a friend of emulating local exception handling by breaks. So, in this case (and even meta case) I would use try { if (filestream.bad()) throw boost::exception("error at opening file"); if (!filestream.good()) throw boost::exception("error inside the file (eof)"); // Main logic xmlLoadFrom(filestream); // assuming that 'xmlLoadFrom' uses exceptions properly as well... } catch (const boost::exception& ex) { log(ex.what()); }
Best regards,
Pierre
PS: if you know a good source about "analysis pattern", don't hesitate to tell me. Right now, I will check the wikipedia page.
I just coined that term - at least AFAIK. What I meant by it? Well, similar to design pattern but applied in the analysis of problems, as a Minsky frame, perhaps. /David