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[REBOL] Re: hash questions

From: rotenca:telvia:it at: 8-Jan-2002 17:08

Hi David, Joel and all
> You can do this in REBOL: > > favoriteLanguage: > [ "Larry" "Perl" > "Carl" "REBOL" > "Guido" "Python" > "Matz" "Ruby" > "Richard" "LISP" > ] > > and then > > >> print select favoriteLanguage"Guido"
You can do also: name: "Guido" print favoriteLanguage/:name The path evaluator make an implict select on block and hash. But the problem here is that if a language called "Guido" appears before the user "Guido" then fails, because the path evaluator doesn't skip anything so it can be used if datatype are different, for example: word! - string! or string! - file! or file! - block! string! integer! and so on. A fetch based on this: fetch: func [k [string!]] [data/:k ] but if k is not found fetch will fire an error (Invalid path value). It is possible to do also a change, if the index is a word (it seems to me a strange thing - what do you think?): data: [guido "Rebol"] change: func [k [word!] value] [k: to-set-word k data/:k :value] change 'guido "What else?"
> However, if you want to maintain a dynamic set of associations > it's a bit more work: > > assoc: make object! > [ data: [] > default: 0 > clear: func [] [data: copy []] > store: func [k [string!] v [string!] /local pos] > [ pos: find/skip data k 2 > either found? pos > [ change next pos v] > [ append append data k v] > ] > fetch: func [k [string!] /local r] > [ either found? r: select/skip data 2 k [r] [default]]
--- Ciao Romano