Re^4: Help me understand this code?

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Re^5: Help me understand this code? by Laurent_R (Canon) on May 22, 2015 at 06:27 UTC
The hash is being defined in this line: `$m{$_} = ++$i for qw[Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec];` [download] After having executed this statement (or maybe I should say this loop), the following structure exists in memory: `( Jan => 1, Feb => 2, ...)` [download] Please beware that this code is fairly sloppy, with no declaration of variables, it is not an example to be followed.	[reply] [d/l] [select]
Re^6: Help me understand this code? by ansabhailte (Novice) on May 22, 2015 at 16:12 UTC
Ok, I get it now. Yeah, I'm still extremely new to Perl but I would never use those variable names in Bash...	[reply]
Re^5: Help me understand this code? by AnomalousMonk (Archbishop) on May 22, 2015 at 08:50 UTC
Further to Laurent_R's post: This is known as "autovivification" (see perlglossary) and is occurring with all the variables in the OPed code except `$a` and `$b`, which are pre-existing Perl special variables (see perlvar). Only package-global variables are created in this way, so this practice is officially Frowned Upon and is precluded by using strictures (see strict). In almost all cases, it's better to pre-declare lexical variables with my. ... what do the pounds in $t#$t#$t do? They match against literal `'#'` characters in a string. They have no special function in a regex unless the `/x` regex modifier is used (see Modifiers), in which case `#` becomes a comment metacharacter/operator and must be escaped in some way to match against a literal character. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re^6: Help me understand this code? by ansabhailte (Novice) on May 22, 2015 at 16:13 UTC
Gotcha. Thanks!	[reply]