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On The Naming of Things

 by Simon Cozens
 Oct. 29, 2002
 


As in certain cults it is possible to kill a process if you know its true
name. 


-- Ken Thompson and Dennis M. Ritchie 


I've been thinking recently about what accounts for the CPAN's success;
well, that's not quite true. I've been trying to work out what accounts for
the Ruby Application Archive and Python's Vaults of Parnassus comparative
failure. 


There are many reasons. First, there's a clear distinction in CPAN between
libraries and applications; the RAA the Vaults don't have such a thing. But
I've come to the conclusion that a major factor, and one which applies both
to collections of software such as those we're looking at and the
development world in general, is the way that libraries and aplications are
named. (To be fair, Ruby is getting better at this and beginning to solve
the problem the Perl way.) 


I'd like to give a couple of principles for naming software. 

Definitive names discourage wheel reinvention 

Perl's modules are generally given simple, definitive names. If I want an
XML parser, I head for XML::Parser. It's that simple. (Of course, if it's
not that simple, I head for XML::Simple which is.) If I want to write a
module for parsing XML and I know that XML::Parser exists, I'm forced to
choose a name which correctly denotes what sets my parser apart; I have to
do something new, and hence I'm not reinventing the wheel. 

Descriptive names are best for libraries 

There's a temptation to make up cutesy names for software projects.
However, when it comes to libraries, this is more of a hindrance than a
help. When I see a module called XML::Parser I know exactly what it does.
It doesn't require any more description. If, on the other hand, it had a
cutesy name - Expat - I would have no idea. Similarly, good naming helps me
quickly locate the library I need. If I'm writing C code to deal with
Unicode, I'd look for a libunicode. And behold, there is indeed a
libunicode which does what I want and I need look no further. That would
not have been quite so easy if it had been called libgeoff. Cutesy acronyms
don't help either - you might know that libgail is the GNOME Accessibility
Implementation Library, but at first sight, that might have been called
libgeoff too. Why not, say, libaccess, or libgaccess if you must have the g
for GNOME. 

End-user projects can have non-descriptive names 

There is a place for cute naming, and that's in applications and other
end-user projects; this is because there's more space for competition.
You'd never get away with calling a web browser "webbrowser", so "Mozilla"
is as good a name as any. However, if you're building that as a Perl
module, then Web::Browser (or Tk::WebBrowser) would be just fine. This
should remind you that some things that you think are applications can turn
out to be libraries, and vice versa - consider spamassassin as an example.
Thankfully, that has both a catchy and a descriptive name, so turns out to
work very well as both a library and an end-user tool. 


Shamans have long known the value of the correct and definitive naming of
things; programmers of libraries and modules would do well to rediscover
it. 


Simon Cozens 


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