"Secure dostring"

[erik@... (Erik Hougaard)]

This is just a brainstorm...

I would like to have a "securedostring" command... That would be a dostring
that only would allow simple expressions and the functions defined in
mathlib .. I would use this to allow my user to type simple expressions in
entry fields, but I do not want my users to be able to call functions (lua
defined) and other C functions..

The most primitive way would be to "pre-parse" the string so that it would
only contain xxx( when xxx is a function in mathlib...

Any other suggestions?

/Erik