[Gambas-user] Files inside executables - access strategy advice (advanced)

[Bruce]

On Sun, 2012-09-02 at 10:32 +0200, Fabien Bodard wrote:
> 2012/9/2 Fabien Bodard <gambas.fr at ...626...>:
> > 2012/9/2 Bruce <bbruen at ...2308...>:
> >> On Sun, 2012-09-02 at 03:54 +0200, Benoît Minisini wrote:
> >>> Le 02/09/2012 03:44, Bruce a écrit :
> >>> > Is there an easy way to access files inside a library or component
> >>> > executable?  Or more correctly, "What is the best way..."
> >>> >
> >>> > I am abstracting some common database methods into a library out of
> >>> > several of our apps.  The problem I am having is that these methods rely
> >>> > on some metadata files that currently have to be copied into each
> >>> > application (and thus is a potential version error source).  I would
> >>> > like to put the metadata inside the library executable so that every app
> >>> > using the library will be using the same metadata files.
> >>> >
> >>> > Here's the structure that is giving me Grief!
> >>> >
> >>> > MyApplication ---uses---> LibAppData ---uses--> LibBO
> >>> >
> >>> > LibBO provides the low level database access and consists of primarily a
> >>> > class that acts as the parent class for all the LibAppData classes,
> >>> > which in turn represent fairly complex "business data objects".  At the
> >>> > moment the metadata representing the persistence maps for the objects
> >>> > reside in a "BOMeta" subdir in (each of) the MyApplication executables.
> >>> > These metadata files are needed by LibBO.  I can access them simply by
> >>> > using
> >>> >          File.Load("BOMeta/" & <objectfilename>)
> >>> > which works fine as it's just like accessing any file within the
> >>> > executable archive.
> >>> >
> >>> > Maybe a real example would help explain.  Two of our major apps are
> >>> > "ManageStable" and "ManageAuctions" (the latter allows the user to
> >>> > submit horses for sale at auctions.)
> >>> > Both of these use a "horse" business object in LibAppData, so they both
> >>> > currently need to have the metadata file "horseBO.meta" included at the
> >>> > application level.  I want to move that metadata file into LibAppData.
> >>> > But then LibBO cannot just access the file using the above simple
> >>> > method.
> >>> >
> >>> > So far I have planned it along the following line:
> >>> > 1) In LibAppData HorseBO._init() needs to copy all its metadata files
> >>> > into a Temp$ directory.  This should be done in _init so that the files
> >>> > are only copied once during an execution, not everytime a horse object
> >>> > is created.
> >>> > 2) LibBO can then expect to find the metadata in the
> >>> > relevant /tmp/gambas.500/<process> directory.
> >>> >
> >>> > However, this fails to impress as firstly, there are over 30 different
> >>> > business object classes and the copy would be invoked every time one of
> >>> > the LibAppData classes is loaded and secondly, only some of the business
> >>> > object classes are used by an individual app.
> >>> >
> >>> > Can anyone see or suggest a better way to do this?
> >>> >
> >>> > tia
> >>> > Bruce
> >>> >
> >>>
> >>> I don't think I have understood everything...
> >>>
> >>> A library can access any file located in the main project (by using the
> >>> special notation "../<path>").
> >>>
> >> Yes, and that works fine.
> >>
> >>> But a library cannot access files from other libraries, and the main
> >>> project cannot access files of any library too.
> >>>
> >> That's right too.
> >>
> >>> A workaround is opening the file where it is accessible, and sending
> >>> File references through libraries.
> >>>
> >> This is the bit that I can't get to work. The library cannot open a file
> >> inside its' @own executable@ using that "special notation" as that
> >> refers to the main project (and therefore I can't send the File
> >> references).
> >>
> >>> Regards,
> >>>
> >>
> >> regards
> >> Bruce
> >>
> >>
> >>
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> >
> >
> > NO, Benoit say that :
> >
> >
> > In the library :
> >
> > Public Function GetFile(sFile as String) as File
> >
> >   Dim hFile as File
> >   Return Open sFile For read
> >
> > End
> >
> >
> >
> >
> > In the main program
> >
> > Dim hFile as File
> >
> > hFile = MyLibClass.GetFile("dir/file")
> >
> > End
> >
> > Then you can use for example
> >
> > Line Input #hFile, s
> >
> >
> >
> >
> > --
> > Fabien Bodard
> 
> Haa and for the invert ... Get the file from the main program :
> 
> Public sub Main
> Dim hFile as File
> Dim hLibClass as hLibClass
> File =Open sFile For read
> hLibClass = New hLibClas(hFile)
> 
> End
> 
> 
> in Library
> 
> Public sub _New(hFile as File)
> 
> dim s as string
> 
> Line Input #hFile, s
> 
> 
> 
Haaaa!!

I finally got it!

I was trying to use "hFile.Load(???)" in the "other" project, which
doesn't (or can't possibly) work.

Reading the returned file line by line works.
(It's amazing how many times I looked at that line of code and couldn't
see the bleedin' obvious.)

Thanks guys.  

Bruce