[gmx-developers] Trade-offs between encapsulation and low level modifications of class variables.

[David van der Spoel]

On 29/10/16 11:32, Erik Lindahl wrote:
> Hi,
>
> Redmine would be good to track the history of the  discussion a year from now.
>
> The big advantage about not being able to change stuff everywhere is that we have a clear owner of data/settings, and when things depend on each other it's clear where they are handled (since it's just one place). It's also wonderful to get rid of the large C structures we were passing everywhere.
>
> So, in general I think it's a decent solution that we have to completely reinitialize new settings if a specific analysis tool wants different settings. While it's trivial to change a single parameter, there could be other settings that depend on it...
>

Thanks, let's continue the discussion here. 
https://redmine.gromacs.org/issues/2068

> Cheers,
>
> Erik
>
> Erik Lindahl <erik.lindahl at scilifelab.se>
> Professor of Biophysics
> Science for Life Laboratory
> Stockholm University & KTH
> Office (SciLifeLab): +46 8 524 81567
> Cell (Sweden): +46 73 4618050
> Cell (US): +1 267 3078746
>
>
>> On 29 Oct 2016, at 09:05, David van der Spoel <spoel at xray.bmc.uu.se> wrote:
>>
>>> On 28/10/16 23:24, Berk Hess wrote:
>>> Hi,
>>>
>>> Have you seen my external pull potential functionality change
>>> (28013db1c1515f01c4d4acd64eb510ead4fef2db)?
>>> I don't know if it's something like that that you would need, or you
>>> would rather have a general framework to modify mdp parameters on the fly.
>>
>> Thanks, that looks interesting too. It would be good to reconcile these approaches - the pull code is in a sense the ultimate applied force.
>>
>> In fact other things may be interesting to modify too on the fly, like charges and force field parameters. This is possible still by hacking the C-structures even though it is not elegant.
>>
>> Not sure whether it may be better to open a redmine than have a mail discussion?
>>>
>>> Cheers,
>>>
>>> Berk
>>>
>>>> On 10/28/2016 08:06 PM, David van der Spoel wrote:
>>>> Hi,
>>>>
>>>> recently (over the last year) I have been working on the electric
>>>> field code as a template for other applied forces. Teemu has done tons
>>>> of work commenting, cleaning up and adding more patches with the
>>>> result that we now almost have a complete framework for reading e.g.
>>>> MDP and TPX files with the same code (correct me if I'm wrong), and a
>>>> JSON mdp file should be doable in the near future as well.
>>>>
>>>> In the process lots of encapsulation has been done of the type "bare
>>>> outside class interface with Impl_ for the details". Obviously this
>>>> has many advantages like decluttered interfaces and modularization.
>>>>
>>>> However, part of the rationale for my changes was to be able to modify
>>>> e.g. the electric field parameters from a program (not mdrun) and
>>>> re-evaluate the energy and dipole of a molecule, which would yield the
>>>> polarizability. The functions to do this are now not accessible
>>>> anymore, except by faking reading a new MDP input, and even that is
>>>> not possible anymore outside readir.cpp since the last few patches
>>>> (most of which I approved :) ).
>>>>
>>>> There may be similar cases, where one would like to change variables,
>>>> like steered MD, certain free energy schemes or analysis tools. I'm a
>>>> bit at a loss how to deal with this, would be great to have some
>>>> feedback on this.
>>>
>>
>>
>> --
>> David van der Spoel, Ph.D., Professor of Biology
>> Dept. of Cell & Molec. Biol., Uppsala University.
>> Box 596, 75124 Uppsala, Sweden. Phone:    +46184714205.
>> spoel at xray.bmc.uu.se    http://folding.bmc.uu.se
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-- 
David van der Spoel, Ph.D., Professor of Biology
Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205.
spoel at xray.bmc.uu.se    http://folding.bmc.uu.se