Re: Library, Bundle or ...

[Richard Frith-Macdonald]

On 8 Jan 2007, at 19:10, Philippe Roussel wrote:

> On Sat, Jan 06, 2007 at 06:43:19AM +0000, Richard Frith-Macdonald  
> wrote:
> > If your widgets have no resources (eg image files), you can first
> > build a library, but if they use resource files you should probably
> > start by building a bundle.  In fact it's probably good to build a
> > bundle even if there are no resource files used ... as a bundle does
> > not have to be linked into applications at compile time in order to
> > be usable.
>
> After working on it a bit, I still don't get it. If I build my widgets
> in a library, I just have to add
>
> Agenda_LIBRARIES_DEPEND_UPON += -lAgendaWidgets
>
> to my application GNUMakefile to use the widget, using a Gorm model or
> not. But if I put my widgets in a bundle, I have to load the bundle
> manually with code like this (I think)
>
> NSBundle *bundle;
> Class MonthView;
>
> bundle = [NSBundle
>   	   	  bundleWithPath:@"/opt/gnustep/Local/Library/Bundles/ 
> AgendaWidget.bundle"];
> MonthView = [bundle principalClass];
>
> How am I (or another developer reusing the widget) supposed to know
> where is the bundle ?

The main advantage of a bundle is that you can include resources with  
it (image files etc) and easily move around the whole bundle to  
wherever you want it.
(You also don't have to load it into your appplication unless you  
actually use it).
The issue of locating resource files is resolved ... because they are  
inside the bundle and the NSBundle class provides standard methods  
for finding them.
That means that all your application needs to do is locate the bundle  
which could be either inside your application (The NSBundle API helps  
you find them) or in a standard shared location if the bundle is to  
be shared by more than one application.

eg.
for a application local bundle ...

bundle = [NSBundle bundleWithPath: [[NSBundle mainBundle]  
pathForResource: @"AgendaWidget" ofType: @"bundle"]];

or to search all standard bundle locations ...

NSEnumerator *enumerator = [NSSearchPathForDirectoriesinDomains 
(NSLibraryDirectory, NSAllDomainsMask, YES) objectEnumerator];
NSString        *path;
while (bundle == nil && (path = [enumerator nextObject]) != nil)
  {
    bundle = [NSBundle bundleWithPath:  [path  
stringByAppendingPathComponent: @"Bundles/AgendaWidget.bundle"]];
  }

> Same question goes for a Gorm palette.

A palette is unrelated to locating the library/bundle, as you don't  
load it into your application.  Your application uses a library or  
bundle to get the code, and Gorm uses the palette when you design/ 
build the application user interface.  To load a palette into Gorm  
you just click the 'Tools' menu item, then 'Load palette', then  
select the palette you wish to use in the open panel.  Alternatively,  
you can set a list of palettes (full paths to the palettes) in the  
user defaults as an array keyed on 'USER_PALETTES' and Gorm will load  
these automatically at startup.

> In short,
> I don't see the advantages of a bundle in this case. May I'm  
> confused...

Well, it depends on your code ... what I wrote in response to your  
original email was:

> If your widgets have no resources (eg image files), you can first  
> build a library, but if they use resource files you should probably  
> start by building a bundle.

ie a bundle is best if you have other resources associated with the  
code, but a library is simpler if you don't.
If you don't have any resource files, and are unlikely to ever add  
any, then using a library is the way to go.
If you do have resource files, make a bundle.

Developers should be able to handle either case easily.