I think writing a parser by hand should be reserved for when
1. You have users.
2. You can demonstrate a marked improvement in performance and/or error reporting with the hand-written parser.
Otherwise, deriving a parser from a grammar should absolutely be the default. Writing parsers by hand is error-prone, causes security vulnerabilities[0], and is very tedious work.
1. You have users.
2. You can demonstrate a marked improvement in performance and/or error reporting with the hand-written parser.
Otherwise, deriving a parser from a grammar should absolutely be the default. Writing parsers by hand is error-prone, causes security vulnerabilities[0], and is very tedious work.
[0]: http://langsec.org/