<p>LPC Basics<br>
Written by Descartes of Borg<br>
23 April 1993</p>
<h3>Introduction</h3>
<p><strong>This manual, how to use it, and its terms</strong></p>
<p>I have seen a lot of requests lately on USENET for LPC manuals. In addition,
the immortals on my mud have been telling how good the building documentation
of Nightmare is, but that there was just no adequate explanation of the LPC
programming language. So I decided to try my hand at writing a manual. Some
things you should keep in mind. LPC is a very easy programming language to
learn, and it has real value in that place most of us know as the real world.
I began playing muds in 1991, and in the space of a month created an unimpressive
area and musician's guild on the original Bates College MUD called Orlith.
After that, I moved to Los Angeles for a year and had no contact with mudding
or computers. In June of 1992, I was back on the internet and a wizard of
Igor. In September of 1992 I began coding the Nightmare mudlib for our use,
and then later decided to distribute it due to there not being any mudlibs
for MudOS at the time that a person could just throw up a running mud with
(now, that of course is not the case :)). So, I have been doing serious coding
for less than a year. As a Philosophy major in a world of Computer Science
majors, I just want to make clear that it is not at all required that you
have ever done anything with your computer than log into a mud in order for
you to really come to understand LPC coding. This manual makes the following
assumptions: Someone has taught you basic UNIX commands like ls, cd, mkdir,
mv, rm, etc. You know how to enter your mud's editor and write a file. No
other assumptions are made. If you know C, you are handicapped in that LPC
looks a lot like C, but it is not C. Your preconceptions about modular programming
development will be a hinderence you will have to overcome. If you have never
heard of the C programming language (like me in May of 1991), then you are
only missing an understanding of the simple constructs of C like the flow
of program execution and logical operators and such. So a C guru has no real
advantage over you, since what they know from C which is applicable to LPC
is easy to pick up. The stuff they know about C which makes them a guru is
irrelevant to LPC.
</p>
<p>The chapters of this manual are meant to be read in order. Starting with
the introduction, going sequentially through the chapter numbers as ordered
in the contents file. Each chapter begins with a paragraph or two explaining
what you should have come to understand by that point in your studies. After
those introductory paragraphs, the chapter then begins to discuss its subject
matter in nauseating detail. At the end of the chapter is a briefly worded
summary of what you should understand from that chapter if I have been successful.
Following that may or may not be some sidenotes relevant to the subject at
hand, but not necessary to its understanding.
</p>
<p>If at any time you get to a chapter intro, and you have read the preceeding
chapters thoroughly and you do not understand what it says you should understand
by that point, please mail me! Clearly, I have failed at that point and I
need to know where it is I have gone wrong so I can revise it properly. Similarly,
if you do not understand what the chapter summary says you should, please
mail me. If your mud is on the MudOS intermud system, mail descartes@nightmare.
Otherwise mail <a href="mailto:borg@hebron.connected.com">borg@hebron.connected.com</a>.
</p>
<p><strong>Some basic terms this manual uses:</strong></p>
<dl>
<dt>driver
<dd>This is the C program which is the game. It accepts incoming sockets (links
to other computers), interprets LPC code defined by the mudlib, keeps mud
objects in memory, makes periodic attempts to clean unused mud objects from
memory, makes periodic calls to objects, and so on.
<dt>mudlib
<dd>LPC code which defines the world in which you are in. The driver of itself
is not a game. It is just a program which allows the creation of a multi-user
environment. In some sense, the driver is like an LPC compiler, and the
mudlib is like a compiler's library (a very loose analogy). The mudlib defines
basic objects which will likely be used over and over again by people creating
in the mud world. Examples of such objects are /std/room (or /room/room),
/std/user.c (or /obj/player.c), and so on.
<dt>area or castle
<dd>Specific creator coded objects which often use a feature of LPC called
inheritance to make use of the properties of basic mudlib objects and turn
them into specific objects to be used by players in the game
<dt>object
<dd>a room, a weapon, a monster, a player, a bag, etc. More importantly, every
individual file with a .c extension is an object. Objects are used in different
ways. Objects like /std/living.c are inherited by objects like monster.c
and user.c. Others are cloned, which means a duplicate of that code is loaded
into memory. And still others are simply loaded into memory to be referenced
by other objects.
<dt>native and compat
<dd>these two terms refer to two popular flavours of drivers. Native mode
mudlibs make use of on the design of LPMud driver 3.0 and later. You may
have a 3.0 driver however, but have a 2.4.5 style mudlib. This is what is
meant by compat mode. Mudlibs which are native mode are any for MudOS, CD,
and LPMud mudlibs that are listed as native. Compat mudlibs are any LPMud
mudlib before 3.0 and those which are 3.* compat mudlibs. I believe Amylaar's
is compat.
</dl>
<p><i>Good Luck!</i><br>
George Reese<br>
(Descartes of Borg)<br>
12 July 1993<br>
<a href="mailto:borg@hebron.connected.com">borg@hebron.connected.com</a>
</p>
