Stages of a Perl Programmer re: Regular Expressions


* Novice
  - thinks regular expressions are line noise
  - falls prey to "m/usr/bin/" (embedded /'s in m//)
  - has no idea what tr/// is
  - doesn't know about the 'i' modifier
  - gratuitous use of $`, $&, and $'
  - doesn't use \w, \d, \s, etc. metaclasses
  - painfully misuses .*
  - puts words in character classes


* Initiate
  - still a victim of leaning toothpick syndrome (LTS)
  - uses regexes where chop() or substr() or index() would do
  - tries to use tr/// like s///
  - uses modifiers needlessly (like 'o' and 's' and 'm')
  - does ($x,$y) = ($1,$2), instead of ($x,$y) = /(re)g(ex)/
  - uses '|' in character classes
  - uses [^\w] instead of \W
  - tries to delete HTML tags with s/<.*>//g or s/<.*?>//g
  - backslashes needlessly


* User
  - uses different m// and s/// delimiters
  - uses regex where index() would do
  - knows about tr///, but uses s/// instead
  - uses regexes in conditionals
  - knows to use the 'o' modifier, but sometimes gets bitten
  - uses backreferences incorrectly sometimes (\1 on the RHS of s///)
  - starts to understand why HTML tags are hard to match with regexes


* Adept
  - knows when to use regexes, and when to use string functions
  - knows when to use tr///, and when to use s///
  - leaves the 'm' off // regexes
  - uses the 'e' modifier in s///
  - toys with look-ahead
  - knows to use (?:...) when a backref isn't needed
  - uses precompiled regexes with qr//


* Hacker
  - uses look-ahead and look-behind with impunity
  - sighs at the constant-width restraint on look-behind
  - plays with pos() and \G and the 'g' and 'c' modifiers
  - has read "Mastering Regular Expressions"
  - knows how to "unroll the loop"
  - uses re.pm -- and understands the debug output
  - uses closures to make regex matching objects
  - makes nested regexes using (??{...})
  - can read a regex and explain its function


* Guru
  - works on the regex engine
  - has patched the engine from time to time
  - uses precompiled regexes as objects
  - refers to "Henry" (that is, Henry Spencer)
  - can explain how any given regex will or won't work


* Wizard
  - adds features to the engine "whenever"
  - has pumpking status