Re: import vs include Re: Porting autogsdoc to OSX

[Richard Frith-Macdonald]

On Wednesday, February 27, 2002, at 11:11 AM, Peter Cooper wrote:

> > Ah ... but we are trying to be compatible, not just use the same API.
> > As much as possible we want
> > to avoid having to locate and link additional frameworks to do what on
> > MacOS is all in one.
> > Not that there is anything particularly hard about linking in extra
> > libraries, but why confuse
> > developers by providing frameworks which have the same API but 
> > different
> > functionality?
>
> It certainly makes development using, say, Cocoa development docs or 
> mass-
> market books easier if APIs live in similar places ;)
>
> On encouraging portable software, to assist people building 
> cross-platform
> apps, eg GNUstep -> OpenStep or GNUstep -> Cocoa it might be useful to 
> have
> some sort of source audit tool for portability.
>
> I suspect that a 100%-correct tool will be impossible to build, but
> something that can flag most compatibility issues during development 
> might
> lead to more portable code being written. After all, not all developers
> have access to the different platforms during the critical early
> implementation phases.

Very tricky.

GNUstep-base provides three relevant mechanisms -

1. API compatibility ...
The header files take note of the STRICT_MACOS_X preprocessor constant 
(and others).

When autogsdoc builds documentation, it uses this information to document
which classes, methods, functions types and constants are in MacOS-X

When you build your software, you can define this constant to remove all 
non-MacOS-X
information from the headers - so the compiler will give you an error or 
warning message
if you try to do anything non portable.

2. Runtime behavior warnings ...
The NSDebug.h defines NSWarnLog and related macros ... when built with 
debug on, this
is used to output warnings when your code does something that may be 
non-portable.

3. Runtime behavior options ...
The user default system is used to control compatibility behavior - 
defining
GSMacOSXCompatible to YES should get GNUstep to do some things in 
MacOS-X ways
rather than OpenStep ways.


Of course, the effectiveness of these mechanisms is only as good as 
peoples reporting
where they get things wrong.  While the first mechanism is probably 
pretty good, the
other two depend on us actually knowing how MacOS-X implemented behavior 
differs from
GNUstep.  Most times, if we find a difference we 'fix' GNUstep.  Other 
times (eg when
the MacOS-X behavior looks like a bug or id brain damaged in some way), 
we put a
warning log in the code.