Re: Lengthy discussion about datafile.c...

[Daniel J S. <dan...@ie...>]

Daniel J Sebald wrote:

> In having done quite of bit of modular and object oriented code for a 
> few years, I'd like to discourage the use of global variables across 
> two conceptually different pieces of code.  In particular, in this 
> instance is the global variable "df_datum".


I see now there are several variables made global outside datafile.c:

 * public variables declared in this file.
 *    int df_no_use_specs - number of columns specified with 'using'
 *    int df_no_tic_specs - count of additional ticlabel columns
 *    int df_line_number  - for error reporting
 *    int df_datum        - increases with each data point
 *    TBOOLEAN df_binary  - it's a binary file
 *        [ might change this to return value from df_open() ]
 *    int df_eof          - end of file
 *    int df_timecol[]    - client controls which cols read as time

Well, then its starting to get to be a lot of work to adhere to a 
modular strategy.  Anyway, things like df_line_number could be done 
differently.  From what I see, that variables is used outside of 
datafile.c only as an argument to error messages when things fail, e.g.,

            int_error(this_plot->token,
                  "2 columns only possible with explicit pm3d style 
(line %d)",
                  df_line_number);

Another approach might be to create a funciton df_int_error() which acts 
just like int_error() but in addition tags on information about the file 
line number it is currently at then calls int_error().  That way, error 
messages for the line number can be made consistent and easily alter if 
for some reason more information is to be added.

Dan