Script/module formatting gotcha

mjscott2702 has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Script/module formatting gotcha by jettero (Monsignor) on Oct 06, 2010 at 13:39 UTC
I use this form quite often... `my ($val) = () = something`; I also use `$this->{key} = my $val = 7;`; it's not a bug. The assignment has a value of the rvalue. Neat!! If you understand this, I don't understand the question... What if I wanted to do this? `$this->{key} = # this is an important note about the next assignment my $val = blarg();` [download] Should I have to then tell critic to ## no critic that?	[reply] [d/l] [select]
Re^2: Script/module formatting gotcha by morgon (Priest) on Oct 06, 2010 at 14:01 UTC
The problem is not that the construction as such is problematic, but that the format of the source-code makes it had to see immediately what is happening (at least that is how I understand the question). And I am afreid that neither perltidy nor perlcritic would have helped a lot here. But `perl -MO=Deparse <your script>` would have.	[reply] [d/l]
Re^2: Script/module formatting gotcha by mjscott2702 (Pilgrim) on Oct 06, 2010 at 13:52 UTC
It's not the construct of assigning an assignment to a variable that I am questioning here, I too use this all the time. The source of my confusion were the hundreds of comment lines between the left and right-hand sides. IMHO, this is a way of making the code more unreadable - yes comments can do that! In your example (which, to be fair has only a single comment line, and is less likely to be confusing), I think it would be clearer to write: `$this->{key} = my $val = blarg(); # this is an important note about the previous +assignment` [download]	[reply] [d/l]
Re: Script/module formatting gotcha by ww (Archbishop) on Oct 06, 2010 at 13:51 UTC
further re jethro's... Alternately, is the question 'how do I reformat/relocate the comment lines so they're not in the middle of the assignment, like yo? `# assign to $var1 the value of $var2: # comment line1 # comment line2 # .... # comment line100 my $var1 = my $var2 = 0;` [download] My suspicion is that that approach to dealing with such infelicitous formating would require a truly wise AI module ... or active if tedious utilization of the connection between brain and fingers.	[reply] [d/l]
Re^2: Script/module formatting gotcha by jethro (Monsignor) on Oct 06, 2010 at 14:59 UTC
I have to protest profoundly to this blatant misuse of my most illustrious name in connection with riff-raff like jettero ;-)	[reply]
Re^2: Script/module formatting gotcha by mjscott2702 (Pilgrim) on Oct 06, 2010 at 13:58 UTC
Agreed, and in this case the AI between the chair and keyboard was the source of the confusion. However, I think it may be a valid as a style to avoid, in terms of readability.	[reply]
Re: Script/module formatting gotcha by oko1 (Deacon) on Oct 06, 2010 at 14:06 UTC
As jettero pointed out, it's an rvalue assignment - and although the code in the example that you cite isn't doing anything worthwhile, the mechanism itself is a perfectly valid and useful one. Without it, you couldn't do things like `die "Syntax: [...]\n" unless my $fname = shift;` [download] and so on. I think that the right perspective here is that the tools are available and usable, but the decision about whether something is useful or not is up to the human. :) -- "Language shapes the way we think, and determines what we can think about." -- B. L. Whorf	[reply] [d/l]
Re^2: Script/module formatting gotcha by mjscott2702 (Pilgrim) on Oct 06, 2010 at 15:27 UTC
Understood, and I have no problem with the rvalue itself being an lvalue (if that makes sense). My only point here was that splitting this construct across multiple lines, with a large number of comments in-between, makes the script difficult to read - the construct itself is clear, and useful :)	[reply]