TITLE: What Is It Like to Make Software?
AUTHOR: Eugene Wallingford
DATE: October 15, 2004  2:57 PM
DESC: Is making software more like gardening than engineering?  Why would that matter?
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BODY:
Earlier this week, my students and I discussed a chapter from
<A HREF="http://www.pragmaticprogrammer.com/">
   The Pragmatic Programmer</A>.
A few students wrinkled their noses at Dave and Andy's use of
gardening as a metaphor for software development.  I know lots
of folks who don't like this and other "soft" metaphors for
making software.  For most folks, engineering and architecture
still make the most sense.

At one level, of course, software development <I>is</I> like
<A HREF="http://www.tcnj.edu/~rgraham/whatare.html">
   engineering</A>.
Software developers design and build artifacts in response
to human needs.  They base their designs on a scientific and
mathematical understanding of the world.  They strive for
processes that are verifiable and repeatable, so that they
can reliably build artifacts that meet their specifications.

But, as I admitted to my students almost in a whisper, I like
the gardening metaphor.  Design, programming, refactoring, and
debugging all have reasonable analogs in gardening, and even
better is the mindset of "cultivating" a system over time.
It's an organic metaphor, and that feels right to me.

We do <I>make</I> software, but software isn't really like
a bridge or an auto.  The abstractness of software makes it
more like a legal argument or a scientific theory.  As a
graduate student, I built models of arguments and theories
and tried to understand how people create them.  There's a
lot of value in taking an engineering viewpoint on these tasks,
but it doesn't always seem much like how people do them.

Of course, the relationship between art, science, and engineering
is a popular topic among reflective practitioners of all three.
In just the last week I ran across an article by a physicist
talking about
<A HREF="http://www.steelypips.org/principles/2004_10_10_principlearchive.php#109767250377932229">
   superstition in scientific method</A>
and an article by an artist talking about
<A HREF="http://www.pyracantha.com/cgi-bin/blosxom.cgi/2004/10/13#EB80blueandorange">
   the mundaneness of artistic craft</A>.
It seems that many seemingly different activities are less different
in the doing than they seem at first glance.

While I appreciate the gardening metaphor and think that it
can help us understand something about what we do, I don't
think it suffices as a model for how we make software.  None
of the metaphors I've heard of do.  That's why I really like
this quote from
<A HREF="http://www.dreamsongs.com/">
   Richard Gabriel</A>:

<BLOCKQUOTE>
Over the years I've tried to make the point that programming
(even in its "hacking" form) is not precisely like anything
else that people do, but is like everything that people do
all at once:  Programming is not engineering, but programmers
do engineering, programming is not art, but programmers need
to be artists, etc.  The totality of the activity of programming
is not like any one thing people do, but because people are
people, we bring to bear all our ways of doing things - alone,
in groups.
</BLOCKQUOTE>

We are just beginning to understand what it is to build software.
Metaphors can both help and limit us in our discovery.
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