Re: Upper/lower case in identifiers

9 Jan 2003

      Frank wrote:
...
As you probably know, GPC currently converts all identifiers to
first letter upper-case/rest lower-case. Since this is often not
nice, I plan to change this. This would affect at least the
following things:
It is not clear to me what change you propose.

You probably mean (because this is easiest to implement) to
(optionally?) drop the conversion altogether and consequently have
case-sensitive identifiers.  This is contrary to Pascal standards, but
has some advantages in the C/Unix-dominated tool world.

Of course, I would NOT recommend

program Example1;

const
  MIXEDCASE = True;

var
  MixedCase: Integer;
  mixedCase: Real;

ALTERNATIVELY, it might be possible to convert all occurences
of the same identifier (modulo case) to the casing found on the
defining occurrence.  Thus

program Example2;

var
  MixedCase: Integer;

...

  readln  ( mixedCase )
; writeln ( mixedcase )

would work properly and all external handling would be via the
identifier MixedCase.

This also seems easy to implement (at the expense of a slightly more
expense compare for lookup) and more in line with Pascal:

	When creating a symbol-table entry you store the casing as found.
	When looking up a name you compare names modulo case (e.g.
	convert both comparands to lower case), when you get a hit
	you use the actual casing found in the symbol table.

This makes Example1 illegal and makes Example2 work as expected.
...
While I'm at it, it might be easy to add a warning if an identifier
is used with varying case (something like `var Foo: Integer; [...]
WriteLn (FOO)').
Such an option would be quite helpful, even if you do not make
changes to the case handling.
...
- Any ideas for the name of the option? (`-Widentifier-case'?)
Seems fine.
...
- Default? (I suppose off, though I think I myself would prefer on.)
I would prefer on, because we have come to know that case variations
of the same identifier are confusing.
...
- Should it work across units/modules? Or should it be a tri-state
 option (never/current file/global)?
Across units/modules would be best, but I can imagine that with
legacy code it might be helpful to restrict the scope of the
checking.

	Tom

Tom Verhoeff

tags

participants (4)