Mixing Dynamic SQL With Non-Dynamic In Stored Proc

I have a Stored Procedure for processing a Bill of Material.

One column on the Assembly Table is a Function Name that contains some busniess rules.

OK, now I'm doing a Proof of Concept and I'm stumped.

Huuuuh!

I will ultimately have about 100 of these things. My plan was using Dynamic SQL to go execute the function.

Note: The function just returns a bit.

So; here's what I had in mind ...

if isnull(@FnNameYN,'') <> ''
exec spinb_CheckYN @FnNameYN, @InvLineID, @FnBit = @FnBit output




CREATE PROCEDURE dbo.spinb_CheckYN
@FnNameYN varchar(50),
@InvLineID int,
@FnBit bit output
AS

declare @SQL varchar(8000)

set @SQL = '
if dbo.' + @FnNameYN + ' (' + convert(varchar(31),@InvLineID) + ')) = 1
set @FnBit = 1
else
set @FnBit = 0'

exec (@SQL)
GO



Obviously; @FnBit is not defined in @SQL so that execution will not work.
Server: Msg 137, Level 15, State 1, Line 4
Must declare the variable '@FnBit'.
Server: Msg 137, Level 15, State 1, Line 5
Must declare the variable '@FnBit'.


So; is there a way to get a value out of a Dynamic SQL piece of code and get that value INTO my OUTPUT variable?


My many thanks to anyone who can solve this riddle for me.
Thank You!


Sigh: For now, it looks like I'll have a huge string of "IF" statements for each business rule function, as follows:
Hopefully a better solution comes to light.

------ Vertical Build1 - Std Vanes -----------
if @FnNameYN = 'fnb_YN_B1_14'
BEGIN
if dbo.fnb_YN_B1_14 (convert(varchar(31),@InvLineID) ) = 1
set @FnBit = 1
else
set @FnBit = 0
END

------ Vertical Build1 - Scissor Vanes -----------
if @FnNameYN = 'fnb_YN_B1_15'
BEGIN
if dbo.fnb_YN_B1_15 (convert(varchar(31),@InvLineID) ) = 1
set @FnBit = 1
else
set @FnBit = 0
END
.
.
.
etc.