[Proj] Motion: add Kristian Evers and Thomas Knudsen to the Proj.4 team

Thomas Knudsen knudsen.thomas at gmail.com
Fri May 20 12:48:38 EST 2016


First, I strongly object to being characterized as a “random rewriter”.

I have used proj since 1993, did my first (tiny) contribution to the code
base in 1999, and I facilitated the inclusion of the etmerc, high precision
transverse mercator code written by my colleague Karsten Engsager, in 2008.

It is correct that I have not touched the code base since then, but that
does not turn me into a “random rewriter”.

Also, I described my intended work, and asked for comments and opinions on
the proj mailing list more than a month ago. It attracted one comment,
which was very much in favor of the work. It did not attract any comments
from you.

Also, the pull request has been open since the beginning of april. Howard
Butler, Even Rouault, and Micah Cochran have commented and given
constructive criticism. I have seen no comments from you.

So all in all, you have had plenty of time to air your opinion. It would
have been very helpful if you had done it a bit earlier than 2 months into
the process. As a long term proj-list member, I know that you are a
frequent and very helpful list contributor, so I have great respect for
your experience and willingness to share it, and I believe you could have
been a very helpful commenter and mentor for this work.

Second: In general I agree with your opinion of “not touching what works”.

However, what “works” is not easily definable - especially not in the long

Kristian Evers and I have turned to proj after having spent time updating
trlib, the transformation system of the Danish national mapping agency (now
SDFE, formerly GST, formerly KMS, formerly GI).

trlib originated as Algol code written around 1961, for the GIER system (a,
for that time, medium sized computer, which was highly optimized for
geodetic computations). The code survived and evolved through more than 5
decades following what was “current best practice” all along.

And the one “best practice” that has been prevalent through all these
decades has been exactly the one you forward here.

The problem is that, while commendable for the medium term, for the long
term “not touching what works” leads to kludge-upon-kludge, from bolting on
additional functionality, while not touching existing code.

In the long term, the “not touching what works” dogma (NTWW in the
following) leads to stale and unmaintainable code.

As an example, for trlib, one of the things we have removed during the last
few years of code revision, is a complete user-space Virtual Menory
mangagement system. It was evidently needed when added to the code around
1970, and left in due to NTWW when the code was migrated from Algol to C
around 1980. And kept ever since, due to NTWW.

So our experience is very much that NTWW should be challenged now and then.
Things change, and so do the hardware platforms the code is supposed to run

The proj.4 macro system reflects a development environment of Tektronix
style, green phosphor 24x80 terminals, where saving vertical whitespace
directly translated into a better general view, by having more context on
screen at a time.

This is not the problem for modern coding tools on modern high-resolution
displays. In today’s coding environment the proj internal macro system is a
high barrier for entry: It makes it extremely hard for new coders to get

If you look at the commit history, you will notice that new people enter
the project in order to contribute one or two new projectione that they

They do not stay to help evolving proj further. I hypothesize that this is
at least partially because the macro system is convoluted and not at all
C-like (e.g. leading to syntax highlighter blues).

My intention was to make the code less impenetrable, in order to make it
more welcoming to new contributors. As you will see when you study the
code, this has been done without touching the algorithmic flow. The
procedure has been designed to enhance the clarity for human readers - not
to touch the flow.

I suggest you read the description “A verbose justification for some highly
intrusive code surgery” I wrote at the very beginning of this work, over at
Hopefully you will see that I have no intentions to break what works - but
at medium time scale intervals, changing what works is necessary in order
to keep things in shape.


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