Checking function parameters/returns

IBM® Informix® 4GL makes function parameter checking at runtime. It is possible to compile a source that calls a function of another module with more (or less) parameters (or return values) as specified in the function definition.

Unlike I4GL, the Genero BDL linker can detect such programming errors when building the program. This is much better as detecting the programming error a runtime.

See the following example:

-- main.4gl
MAIN
    CALL func(1,2)
END MAIN

-- mod1.4gl
FUNCTION func(a,b,c)
    DEFINE a,b,c INT
END FUNCTION

$ c4gl -c mod1.4gl 
$ c4gl -c main.4gl 
$ c4gl -o main.bin main.o mod1.o
$ ./main.bin  
Program stopped at "mod1.4gl", line number 2.
FORMS statement error number -1318.
A parameter count mismatch has occurred between the calling 
function and the called function.

$ fglcomp mod1.4gl
$ fglcomp main.4gl
$ fgllink -o main.42r main.42m mod1.42m
ERROR(-6200):Module 'main': The function mod1.func(3,0) will be called as func(2,0).