Re: [Gm2] Shared library support in Modula-2

[Andreas Fischlin]

Dear Gaius,

The more dynamic loading is done, the better for a modular language such 
as Modula-2. The performance penalty is minimal according to our 
experience with MacMETH featuring a dynamic linking loader since mid 80es!

Regards,
Andreas



Gaius Mulley wrote:
> Hi,
>
> As mentioned in a previous email, I think there are three main ISO
> Modula-2 language features that remain to be implemented.  (Type
> COMPLEX, multidimensional unbounded arrays and to finish exception
> handling).
>
> Coupled with exception handling is module initialisation and
> finalisation - both straightforward - however they do lend themselves
> to fit nicely with shared library support and map onto the shared
> library constructor/destructor.  This raises the question of whether
> to implement inter module procedure calls by using dlopen/dlsym.  In
> effect a module could have an array of void *'s which are contain the
> address of each and every external procedure call.  Initially each
> array element could be directed to the default handler which looks up
> the symbol name in the external shared library.  Once looked up the
> address would be stored into the appropriate array element ready for
> next time the procedure is called.  Of course a similar scheme would
> need to be done for external variables.
>
> Alternatively shared library support could just map the initialisation
> and finalisation calls onto the same shared library
> constructor/destructor.  Any inter procedure calls could be linked
> using traditional `ld' calls.  Or put another way multiple modules
> could be linked into a single shared library using `ld'.
>
> I guess the advantage with the first method is that it would be
> possible to compile every library as a shared library.  Finally
> the user could run the runtime system followed by the main module
> name and watch the application come to life via a series of
> dynamic library loads.  Ie:
>
>   m2 modulename
>
> It might be quite nice from the perspective of IDEs, maybe.  Although
> it would contain a slight performance cost.  My question is, whether
> this is sensible or what users want?  Or do you want both :-)
>
> regards,
> Gaius
>
>
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>   

--
<pre>________________________________________________________________________
Andreas Fischlin, Ph.D., Group Director

Terrestrial Systems Ecology
Institute of Integrative Biology: Ecology, Evolution, Infectious Disease
Department of Environmental Sciences, ETH Zurich

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