--- In firebird-support@yahoogroups.com, "Steve" <steve_goa@...>
snip...

> I understand this, and am doing this in fact. However, I have a special requirement that the UDF further calls a stored procedure to retrieve some data from the database (it is an expression evaluator and calculator, whose input includes regular arithmetic expressions, and functions that depend on data from the database ).
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> Yours sincerely,
> Steve Faleiro

It seems to me, naively perhaps, that all you want to do should be possible without resorting to this ill-advised technique.

Given you have both ends of the problem (i.e. database ddl & UDF) can you not simply return and interrogate values from the UDF that would then decide whether to invoke the stored procedure.
Tom