reduce line of code

Sun751 has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: reduce line of code by CountZero (Bishop) on Jul 14, 2009 at 06:30 UTC
`my $cmd = $step_no ? $step_no : 0;` [download] CountZero A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James	[reply] [d/l]
Re: reduce line of code by Your Mother (Archbishop) on Jul 14, 2009 at 06:16 UTC
This is probably what you're after. `my $cmd = $step_no \|\| 0; # If $step_no is 0, it assigns... uh, 0 over it.` Note that if you're accepting user input, like `$step_no = param("step")` or something you should validate all user parameters before using them in other code. Perhaps- `my $cmd = $step_no =~ /\A\d+\z/ ? $step_no : 0;`	[reply] [d/l] [select]
Re^2: reduce line of code by ysth (Canon) on Jul 14, 2009 at 06:36 UTC
I often prefer setting a default, then overwriting with the validated value: `my $cmd = 0; $cmd = $step_no if $step_no =~ /\A\d+\z/;` [download] -- Online Fortune Cookie Search Office Space merchandise	[reply] [d/l]
Re^3: reduce line of code by lima1 (Curate) on Jul 14, 2009 at 08:52 UTC
I guess this is what Sun751 meant. His non-working example scopes the $cmd variable to the if ... else blocks.	[reply]
Re^4: reduce line of code by jeanluca (Deacon) on Jul 14, 2009 at 09:26 UTC
Re: reduce line of code by JavaFan (Canon) on Jul 14, 2009 at 09:40 UTC
Yes, you can replace it with the empty statement. All you are doing in each block is setting a variable which is lexical to the block - and will hence be gone on block exit. Effectively, the above statement does nothing at all (unless there's some magic attached to `$step_no`).	[reply] [d/l]
Re: reduce line of code by ikegami (Patriarch) on Jul 14, 2009 at 15:05 UTC
Already mentioned: `my $cmd = $step_no ? $step_no : 0;` [download] Simplifies to: `my $cmd = $step_no \|\| 0;` [download] If `$step_no` is only false when `$step_no` is zero, then it can even be simplified to `my $cmd = $step_no;` [download]	[reply] [d/l] [select]