I am still understanding Perl, but what bothers me some examples with open filehandles closing them and the diamond operator with the special $^I variable. What bothers me: why using open for read and write when we can use <> ? The diamod did the better job for me actually.
Update on 28.09.2012
I`ve found an excersise in Lama book on page 168 in which as an extra credit at 4 and 5, I think was the using of the diamond operator. Solving these two ex-es, I`ve found out that diamond has some better feats than open/close ( for text files since you always read and write ( consider you`ve used the -i variable ), however you can miss the --rwx check of the file and try to process a root file or unreadable/writable one. However I think that both are useful for different tasks, I think I`ve solved my mystery about the diamond operator, also I was wondering ( by my assumption the answer is 'NO') if diamond can fseek the file or you can just match with __LINE__ variable... Open/close still puts a fpointer to the file while diamond is some kind of magic using a copy and original files... Maybe this is a strong point if you worry about losing a file. And... I doubt that diamond can open db and binary files, it`s just my guess, I may fail at it too.