Setting ispell-local-dictionary using file contents

[Luis O. Silva]

Dear Emacs community,

I'm planning to use the contents of a file to set the
ispell-local-dictionary variable. I'm not sure where to begin
from or whether this have been done before, but I'm thinking
of a function like the following:

1. Begin a search process to find some keywords

2. If this keywords are in language x (i.e. they're the
   x-keywords), set the ispell-local-dictionary variable to x.

3. Begin the spell checking process.

I think the words in a file completely determine what ispell
dictionary must be used.  Obviously, something like:

;;; ispell-local-dictionary: x

is redundant information.

Does anyone know if this has been done? Is there some hint to
help me in attaining this goal?


Thank you very much in advance.
luis