[Gambas-user] INC and DEC on BOOLEAN data...

[Stephen Bungay]

Benoit Minisini wrote:
> On dimanche 11 mai 2008, you wrote:
>>    IMHO this is broken thinking. It might be a little more typing to use
>> VarName = NOT VarName but it is decidedly more transparent as to what
>> datatype 'VarName' is and what is being done to it.
>>
>> Success = Not Success
>>
>> vs
>>
>> INC(Success)
>>
>> DEC(Success)
>>
>>    In the first example it is very clear what is being done, even when
>> Hungarian notation is not being used, whereas in the second example all
>> that is clear is that a value is being incremented or decremented. INC
>> and DEC implies a change in direction (up or down) to a numeric value,
>> while NOT implies a change in state, which is more analogous to a toggle.
>>
>>    I think, and perhaps I'm wrong on this, that a 'data type mismatch'
>> error is the proper response to those trying to INC or DEC a boolean.
>>   Sorry, I just had to reply, when I see things like this it makes me
>> cringe, like someone dragging their fingernails on a blackboard makes me
>> cringe.
>>
>>
>> Kindest regards
>> Stephen Bungay
>>
> 
> Boolean and Integer values can be converted into each other in Gambas:
> 
> True -> -1
> False -> 0
> 
> 0 -> False
> Any other value -> True
> 
> Incrementing or decrementing a boolean variable actually incremented or 
> decremented its integer converted value.
> 
> INC False -> Inc 0 -> 1 -> True
> INC True -> Inc -1 -> 0 -> False
> 
> DEC False -> Dec 0 -> -1 -> True
> DEC True -> Dec -1 -> -2 -> True ? 
> 
> Weird, so this was fixed in Gambas 2.6, so that DEC True -> False. Otherwise, 
> you will have to remember that INC toggle, but not DEC. I found that too 
> complex for my own brain.
> 
> This is coherent with the common behaviour of Gambas. I mean you can INC or 
> DEC dates too, as Date and Float can be converted to each other.
> 
> You can ignore this feature if you don't like it. Anyway, it cannot be removed 
> in 2.x for backward compatibility reasons.
> 
> I could remove it in 3.0, and replace it by a NOT instruction that would do 
> the same thing only for booleans:
> 
> NOT MyMenu.Checked ' for example
> 
> Regards,
> 

   Yes, just because the feature is there doesn't mean the programmer 
(me in this case) has to use it. Or, as I've become fond of saying, 
'Just because something CAN be done a certain way doesn't mean it SHOULD 
be done that way'.
   INC and DEC makes sense on Dates since it implies a direction, into 
the future or back in the past, as opposed to the state change of On or 
Off, True or False a boolean value implies.

   Personally I think I'll just stay with the already implemented BASIC 
syntax and use;

MyMenu.Checked = NOT MyMenu.Checked

   as it is clear as to it's intent. With typeahead already working to 
reduce typing there is little in the way of extra burden to the 
programmer as far as keystrokes go.

IMHO, creating a 'NOT' instruction confuses things further since;

MyMenu.Checked = Not MyMenu.Checked

and

NOT MyMenu.Checked

   would produce the same result, however the latter looks more like an 
incomplete conditional than an assignment statement.

   IMHO it is a good idea to Deprecate the INC and DEC on BOOL datatypes 
in Gambas 3.0.

   GAMBAS is your baby Benoit, and you have done the Linux community a 
great service with it. I really have no place making any suggestions and 
thank you for taking the time to read my thoughts on the subject, 
however naive they might be.

Stephen Bungay