[Users] numrel/simfactory SVN commit 1296: /branches/PYSIM_2010/mdb/optionlists/

[Ian Hinder]

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On 16 Mar 2011, at 19:51, Frank Loeffler wrote:

> Hi,
> 
> On Wed, Mar 16, 2011 at 05:27:57PM +0100, Ian Hinder wrote:
>> What is the reason for requiring the Fortran and C++ bindings
>> to be present in everyones' HDF5 library?
> 
> They are not required for everyone. I only changed the option list I use
> for my laptop (and others also might use for Debian systems) to build
> the HDF5 library within Cactus. You are free to use another option list,
> but without this the Einstein Toolkit will not build, as it (still)
> depends on the Fortran interface of HDF5.


I'm not talking about your commit - it was only your commit which reminded me of the issue.  I'm talking about Erik's commit to ExternalLibraries/HDF5 from a while back:

	r17 | eschnett | 2010-09-11 01:18:38 +0200 (Sat, 11 Sep 2010) | 4 lines
	Enable C++ and Fortran support.
	Do not enable Fortran support if there is no Fortran 90 compiler available.

This commit not only enables C++ and Fortran support, it makes it mandatory in any HDF5 installation used.  I am arguing that since it is not needed by all people, it shouldn't be made mandatory.  

One option would be to detect if the HDF5 installation chosen has these features, and if so, to link the required libraries in the HDF5 thorn.  In that case, a thorn which needed, e.g., the C++ HDF5 bindings would give an error when it tried to include the header file.  

Whether these are needed or not is dependent on what thorns are present in the thornlist.  Could we define new capabilities HDF5_CPP and HDF5_FORTRAN which are then "required" by those thorns that need them?  Then the HDF5 thorn could detect if any thorns needed them and give an error early on?

An alternative would be to introduce two additional thorns, HDF5Fortran and HDF5CPP, which are each responsible for adding the appropriate libraries to HDF5_LIBS.  I don't like this solution though.

- -- 
Ian Hinder
ian.hinder at aei.mpg.de

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