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- Subject: Re: Direct access to key/value table items?
- From: Ando Sonenblick <ando@...>
- Date: Sat, 09 Aug 2003 23:26:08 -0700
Again, thx Peter...
> How to find the key for a table value?
Interesting direction... And maybe I'm not grokking it immediately, but it
doesn't seem to suit me need immediately.
Based on your description (and the code at
http://lua-users.org/lists/lua-l/2003-06/msg00559) this maps values to keys;
whereas, I want to map indeces into the table to keys...
That is, for a table of key/value pairs, give me the key (or value,
ideally), of the 'nth' item in the table....
Kinda strange this isn't available, IMHO.
> How to find the key for a table value? Since Lua doesn't keep this
> information in the table, you must either search the table, or build
> another table with the reverse mapping of values to keys.
Another thing: you mention that "Lua doesn't keep this information in the
table". It doesn¹t ? Now THAT seems odd. Where does it keep it?
I'm trying to not look at lua's implementation of most things, as I'd be
tempted to duplicate/modify them to suit my needs which would jeopardize
future lua compatibility, but I'm beginning to think that I might need to...
> You could even add a __newindex event to the metatable for t so that the
> reverse table is built incrementally as key/value pairs are added to t.
This makes some sense and is worth looking into... I definitely feel
there are myriad solutions to my problem; it's merely a matter of teasing
out the most appriopriate...