Re: get_fldbuf(variable-field-name)

If you've been following this thread, page up a couple of screens. My original message, edited for brevity (which does little in my case ;) |I have a problem that cannot be solved by standard 4GL. I am trying to |improve upon the FourGen help subsystem in ways that I'd rather not |detail right now. The main issue is that I need a uniform way to get |the value in the current field at the moment the user presses a |function key for field level help. FourGen has already generated the |code to save the name of the current field in a "before field" clause. |I'd like to use that string - the field name - to call get_fldbuf() and |obtain the value currently in that field. This cannot be done in 4GL; --SNIP (Description of experiment, request for undocumented info) SNIP-- Marco Greco Responded: (Also edited for clarity) |the following snippet comes straight from the fglc2 precompiler and |shows the expansion of get_fldbuf | |static _EFFIELD _sqfldlst[] = { |{".customer",0}, |{0}}; | |fgl_nret = _ef_fldbuf(_sqfldlst, &_sqicb); |if (fgl_nret != 1) |... | |Since you will have to play with the internal workings of 4gl, my |feeling is(I thought of doing something like that, years ago) that | |1) whatever you do, you will only be able to do it with 4gl-c |2) you will have to write some sort of precompiler that adjusts | 4gl generated c code to include a reference to the appropriate | _sqicb struct | |All in all, if at all possible, you're better off doing it the |traditional way: a huge case. This is Jake again. Marco, I took you up on your expanded code and also looked at the expansion of the CONSRUCT statement. The expanded code opens a program block with a left brace "{" and defines a variable local to that block only. It is defined as: _EFICB _sqicb; where _EFICB is a typedef of a reasonable but loooong structure we might call an Input Control Block. The pseudo-call to get_fldbuf() expands, as y'all can see above, to passing an array of ASCII field names and the address of the input control block, in this case &_sqicb. The actual C function called is _ef_fldbuf(). As Marco pointed out, I cannot do this in direct 4GL. If I want to pass the address of the local _sqicb to a function, I would have to finagle with the generated ec code. Riiiiight! I don't have enough grief in my life! :-^)) I was willing to write 4gl-wrappers for callable C functions but messing with generated code is a recipe for brain damage. In a spirit of denial-of-futility, I might repeat an old request that Informix add features to 4GL to make aspects of the internal structures (like input and field control blocks) more accessible to the programmer. But I have been asking for these features for so many years, I've lost my spirit. (Sounds like I need a beer. ;-) -- Jake (In pursuit of undomesticated aquatic avians) +-----------------------------------------------------------+ | Impeccable Logic: A thought process which successfully | | resists chicken bites | +-----------------------------------------------------------+