SPUG: Readable, well-written code (was: Best One-Liners and Scripts for UNIX)

[Jeremy Kahn]

Brian Hatch wrote:

>>Grep has more cohesion than a loop because its function is limited
>>to selecting members from a list.
>>    
>>
>Well, not always:
>
>	grep { s/(\d+)/ $1 * 2 /e } @list;
>
>That'll take the first string of numbers in each element of @list
>(perhaps lines from a file) and double the number.  It's actually
>modifying @list, not just selecting members.
>
>Is more readable than the following?
>
>	for ( @list ) {
>		s/(\d+)/ $1 * 2 /e;
>	}
>
>Well, the grep one is cleaner to me - less lines to read.  
>
My take on this is that just because you *can* use 'grep' in place of 
'for' doesn't mean you *should*.

If the goal is to put it on one line, do this:

   for (@list) { s/(\d+)/ $1 * 2/e }; # semicolon because it clarifies 
that I think of this as 1 statement

If the goal is to put the list on the right, use the wacky 
postconditions that Tim hates (you can leave the
braces out if you like):

  { s/(\d+)/ $1 * 2/e } for (@list);

>Others may dissagree, and I wouldn't include it when teaching someone for the
>first time how to do that.
>  
>
IMO, grep should really be reserved for searching through a list and 
picking out certain elements. The "side effect" of changing the list is 
black magic that is unexpected and scary.

My $0.02,

Jeremy