[Mono-dev] Porting System.Numerics from referencesource, approaches for copying code?

Miguel de Icaza miguel at xamarin.com
Sat Nov 29 16:21:50 UTC 2014

Thanks Alex.

I do not think that we will have a strict rule for when to copy and when to

There are scenarios where we will want to keep a lot of the code in one of
our files, and pull code from the referencesource.   At that point, we will
have to determine whether the use of #ifdefs or partial classes is a better
long-term maintenance approach than copying the source.

In this particular case, I feel that we can modify the reference source,
and add the #if MONO around it.

The reason is that the changes are pretty straight forward, it is mostly
about disabling code, and not about picking some specific bits of code and
putting them on our tree.   So an #if would be nice, since we can do a few
things (a) we can later find out what code is being disabled by the port
(looking at work we can do in the future to import new versions, or
contribute back to .NET) and (b) the changes are minimal right now.


On Sat, Nov 29, 2014 at 10:59 AM, Alexander Köplinger <
alex.koeplinger at outlook.com> wrote:

> Here's the diff between my trimmed version and the original:
> http://www.mergely.com/9E70e5Ls/
> Hmm, I actually think that most of the removed methods don't matter (as
> they aren't called anyway). I just wanted to make the file only contain the
> code that is necessary.
> The only "real" changes I had to make where accesses to internal fields in
> NumberFormatInfo, I just replaced them with accesses to the public
> properties that read them.
> Maybe it makes more sense to correct those accesses directly in the
> referencesource, so we can reference it from there?
> As a general guidance, when should we copy something to the Mono tree vs.
> editing referencesource? And if we copy, should we keep unneeded methods or
> remove them?
> -- Alex
> ------------------------------
> From: miguel at xamarin.com
> Date: Sat, 29 Nov 2014 10:40:10 -0500
> Subject: Re: [Mono-dev] Porting System.Numerics from referencesource,
> approaches for copying code?
> To: alex.koeplinger at outlook.com
> CC: mono-devel-list at lists.ximian.com
> Hey Alex,
> In general, the approach works.
> I am curious as to what is that you had to remove, and why.   Can you
> describe the needed changes?   (I saw the diff, but it is hard to tell what
> happened with it).
> I thought that Numerics was pretty much standalone.
> On Sat, Nov 29, 2014 at 10:32 AM, Alexander Köplinger <
> alex.koeplinger at outlook.com> wrote:
> Hey, I've been trying to port System.Numerics (BigInteger, Complex
> classes) from referencesource to see and feel what the process looks like.
> It mostly went fine, but there was one file (number.cs) I couldn't
> reference directly from the submodule and had to copy to the assembly folder
> in the Mono tree.
> I had to remove a bunch of code from that file to trim it down to only
> what is needed for System.Numerics to compile (all the tests pass now as
> well).
> Question: is this a valid approach or is there something better? Note that
> ifdefing the file wasn't feasible as it originally sits inside corlib and
> has many other unrelated methods in it.
> Here's the commit with the WIP:
> https://github.com/akoeplinger/mono/commit/d7c461155a975a35f76b79ebcc3fe33407bd5dce
> -- Alex
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