Re: [AD] Function parameter ordering conventions

["Stephen Apostolopoulos" <stapostol@xxxxxxxxxx>]

On Thu, 21 Jun 2007 11:33:01 +0300, Evert Glebbeek <eglebbk@xxxxxxxxxx> wrote:

> > Eh, this is just asking for trouble! You want an interface to be
> > consistent: a new user using al_draw_bitmap should be right to
> > assume that
> > similar functions would work roughly the same (al_put_pixel is similar
> > enough, three parameter, one is a pointer). If the above syntax was
> > used,
> > he would have to make a round-trip to the manual for every single
> > function, because he'd never be sure what the parameter order would be
> > like - not good!
>
> Not at all! As was pointed out, the convention then becomes that
> primitives follow the pattern "position and geometry" followed by
> "colour", while blit operations become "what to blit" followed by
> "where and how". They are logically distinct.
> It's a matter of how you read the code. If I draw a bitmap, I draw "a
> bitmap" at "some location". If I draw a pixel, I set "a pixel
> somewhere" to "a colour".

Position - Geometry - Colour	(primitive)
Position - Color		{pixel)
Bitmap   - Position - Mode	(bitmap)

This distinction is arbitrary - why should a bitmap follow a different  
convention from a colour? Does handling distinct 'objects' (bitmaps,  
colours, whatnot) differently convey some significant advantage to the  
developer or the user? If not, then the path of least resistance would be  
to treat them all the same:

Position - Colour - Geometry	(primitive)
Position - Colour - (Mode?)	{pixel)
Position - Bitmap - Mode	(bitmap)

or maybe

Geometry - Colour - Position
Colour   - Position
Mode     - Bitmap - Position

I think the second is the easiest to use: you can automatically type in x,  
y and the object/mode, whereas in the first you have to make a conscious  
distinction between colours and bitmaps (muscle memory fails!). The third  
one *seems* a bit stranger than the second, but I've never actually used  
it so I can't make a decision.

What is the advantage of the first proposal over the second or third?


Stephen A