RE: Help with plugin concept
By using an "eval()" type function as in:
http://www.topica.com/lists/EUforum/read/message.html?mid=1716043152&sort=d&start=28878
would work very good for plugins, and many other things.
Juergen Luethje wrote:
>
>
> Patrick Barnes wrote [quotations rearranged]:
>
> >> From: Robert Craig
> >> Date: Sat, 14 Feb 2004 12:50:59 -0500
> >>
> >> Juergen Luethje wrote:
> >>> I believe using the next version of the interpreter, programs still
> >>> can take advantage of a dynamic include technique, when the code is
> >>> just put into 2 files rather than 1. Then again there are 2 separate
> >>> steps:
> >>>
> >>> ------------------------[ part1.exw ]------------------------
> >>> P_S = open ("plugins.ew", "wb")
> >>> puts(P_S, PluginS)
> >>> close(P_S)
> >>> system("exw.exe part2.exw", 2)
> >>>
> >>> ------------------------[ part2.exw ]------------------------
> >>> include plugins.ew
> >>> -- Here comes the main program ...
> >>>
> >>> This should work with the interpreter 2.5, shouldn't it?
> >>
> >> Yes.
> >>
> >> Igor Kachan wrote:
> >>> Another way is just .bat file (without system_exec() in the first part)
> >>> (untested project for 2.5 and better versions
> >>>
> >>> @ rem -- code of ide.bat
> >>> @ rem -- part1.exw prepares all plugins as common include file
> >>> @ exw.exe part1.exw
> >>> @ rem -- part2.exw executes IDE with plugins
> >>> @ exw.exe part2.exw
> >>> @ rem -- end of code
> >>>
> >>> This is EU, isn't it ?
> >>
> >> Yes, that will work too.
> >
> >
> > The only problem with this method of plugins....
> >
> > The resulting IDE is still monolithic... let me explain:
> >
> > If you load/install a 3rd party plugin for your ide, that is missing an
> > external include, or has bugs...
> >
> > Then prg2.exw, or whatever you call it, will crash. And the user will
> > not
> > necissarily know what has happened, and unless the plugin
> > installer-loader
> > is separate from the main ide, there is not a user-level way to unload
> > it.
> >
> > I know that the trickery that you have described will work, as long as
> > all
> > the plugins are perfectly working. However, for a more robust ide, the
> > idea
> > of dll's and an API is much better, as it allows for some kind of "This
> > plugin could not load" message, and for the IDE to continue functioning.
> >
> > Unless of course, Rob allowed an "include(sequence file)" function, that
> > returned either 0 for success, or an error code showing how the include
> > failed... It's ok Rob, maybe for Eu2.6
> >
> > ;oP
>
> Derek already wrote something about different types of plugins.
>
> When a plugin is a DLL, a serious bug also can cause a program crash.
>
> As I understand it, "API" is a general expression, i.e. this term does
> not only refer to DLLs. I think any program, that wants to utilize 3rd
> party plugins, should provide an API, regardlesss what way the plugins
> are technically implemented.
> For example Judith can say, that any plugin should have a function
> called plugin_id() that returns say Judith's birthday times PI or
> whatever. If the function returns a different value, the main program
> can raise a "File 'xyz' is not a proper plugin." message.
>
> If the main program calls a routine in the plugin that does not exist,
> the program will crash, regardless wether the plugin is an interpreted
> EXW file, or a DLL. In this situation a crash can be prevented by using
> the routine_id() technique, and this will work with interpreted EXW
> files as well as with DLLs.
>
> Please notice that these are just some general considerations. I don't
> want to recommend anything concerning plugins, because I've little
> experience in this field.
>
> Regards,
> Juergen
>
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