Laufeyjarson writes…

This Practice is to encourage the use of a for loop instead of while plus a counter.  It reminds us of redo, a Perl feature I always forget which lets us do the loop over at this iterator.  If the only place the while loop does not increment is to try again, a redo fits perfectly.  If the loop has to do more complex changes to the iterator – back up, start over at zero, whatever – then you’ll sill need the more complex while+counter. (more…)

Mr. Conway disagrees with some of my college professors again.  He says that it is not useful to abuse loop constructs just to consolidate control in a single location.  He is a hero for this stance. (more…)

This suggestion seems oddly worded to me, although I’m not sure I can think of a better one.  The book says, “Reject as many iterations as possible, as early as possible.”  Luckily, it goes on to explain what this means, as that isn’t – at least to  me – terribly clear.  It winds up being an extension of “coding in paragraphs” and is more about how to organize your code than how to format it.  I think I agree with this and do it all the time, despite having had many college professors claim it is the root of all evil. (more…)

This suggestion from the PBP is simple: Don’t use do … while loops.  The reasoning is good and readable alternatives are provided.  I wind up having no trouble with this suggestion, although I wasn’t as happy with it when I first read it. (more…)

Mr. Conway suggests that you can cascade uses of the ternary (?:) operator instead of an if-elsif-else chain.  He feels this is much more readable.  I strongly disagree. (more…)

The idea behind this Best Practice is to explain how a table lookup can be used instead of an if/elsif/elsif/elsif/elsif/else block to make selections from a set of constants.  This is almost always a good choice! (more…)

The PBP say “Avoid cascading an if.”  At first glance, this sounds like a pretty harsh suggestion.  As it turns out, I rarely ever have any issue following this suggestion.  Well organized code seems not to need long if/elsif/elsif/elsif/elsif/else blocks. (more…)

Mr. Conway suggests the very firm, “Never modify $_ in a list function.”  I’m torn on this. (more…)

The PBP suggests we factor complex map blocks into subroutines.  Please, please do this! (more…)

The last Best Practice suggested using map instead of a for loop to process lists.  There is an exception suggested by the Best Practices; if you’re transforming a list in place, use a for loop. (more…)