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quakeforge/tools/qfcc/doc/qfcc.lyx
Bill Currie 997102fea8 audit the usage of "only" 
There are still a few iffy places (notably around certain prepositions), but
the relevant sentences are now much easier to read.
2010-01-13 06:42:26 +00:00

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#LyX 1.3 created this file. For more info see http://www.lyx.org/
\lyxformat 221
\textclass scrbook
\language american
\inputencoding latin1
\fontscheme pslatex
\graphics dvips
\float_placement htb
\paperfontsize 12
\spacing single
\papersize letterpaper
\paperpackage a4
\use_geometry 1
\use_amsmath 0
\use_natbib 0
\use_numerical_citations 0
\paperorientation portrait
\leftmargin 1in
\topmargin 1in
\rightmargin 0.5in
\bottommargin 1in
\secnumdepth 2
\tocdepth 2
\paragraph_separation skip
\defskip medskip
\quotes_language english
\quotes_times 2
\papercolumns 1
\papersides 2
\paperpagestyle headings
\layout Title
The Ruamoko Programming Language
\layout Author
Bill Currie
\begin_inset Formula $\bullet$
\end_inset
Jeff Teunissen
\layout Publishers
QuakeForge Press
\layout Uppertitleback
This manual is free; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.
\newline
\newline
This manual is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
\newline
\newline
You should have received a copy of the GNU General Public License along
with this manual: if not, write to:
\newline
\newline
Free Software Foundation, Inc.
\newline
59 Temple Place - Suite 330
\newline
Boston MA 02111-1307
\newline
USA
\layout Lowertitleback
Copyright © 2002-2003 Bill Currie and Jeff Teunissen
\layout Standard
\begin_inset LatexCommand \tableofcontents{}
\end_inset
\layout Addchap
Preface
\layout Standard
In December 1996, Id Software released
\emph on
Quake
\emph default
to the world.
It's doubtful that they knew at the time that it would spark a revolution
-- but such a revolution happened.
To the game industry's surprise, people were getting the game not just
to play it, but to
\emph on
change
\emph default
it\SpecialChar \@.
For the first time, people could make whole new games based on the Quake
engine without having to rewrite the whole game -- and in fact you couldn't
rewrite the whole game, because the main source code wasn't available to
the general public.
What
\series bold
was
\series default
available was something new -- the game wasn't just a game, it was a virtual
machine that had a byte-code instruction set -- and it had a compiler that
you could use to make new games to run inside that engine.
The language (called
\emph on
QuakeC
\emph default
) was kind of crude, and the compiler was even more crude -- but it was
a revolutionary development.
\layout Standard
Now, let's fast-forward to another December -- this time, three years later.
In another revolutionary move, Id Software released the source code to
the complete Quake engine.
This gave many people the opportunity to do a lot more than just make
\begin_inset Quotes eld
\end_inset
mods
\begin_inset Quotes erd
\end_inset
for Quake.
Instead, people could make all-new games without using Quake itself.
Many projects started up around this source code, with many aims\SpecialChar \ldots{}
but one
project grew to be the most dominant: That project is
\emph on
QuakeForge
\emph default
.
\layout Standard
QuakeForge has developed a number of interesting things involving the Quake
engine, but most of them are beyond the scope of this manual.
This manual documents the
\emph on
Ruamoko
\begin_inset Foot
collapsed true
\layout Standard
The name Ruamoko comes from the Maori name for their god of volcanoes and
earthquakes.
According to myth, Ruamoko is not yet born, and when he shakes inside the
Earth-mother, the world trembles.
\end_inset
\emph default
language, a language based on Id Software's QuakeC, but which has been
expanded in ways far beyond the original language.
\layout Standard
The idea behind this book is to give new programmers a solid foundation
in both of the programming models (procedural and object-oriented) supported
by the Ruamoko language, while giving experienced Ruamoko programmers a
complete reference for development of game code.
\layout Standard
\begin_inset FloatList figure
\end_inset
\layout Part
Classical Programming in Ruamoko
\layout Chapter
\begin_inset LatexCommand \label{cha:A-Tutorial-Introduction}
\end_inset
Introduction: Foot, Meet Mister Rocket Launcher
\layout Standard
Let us begin with a quick introduction to Ruamoko.
Our aim here is to show the basic elements of the language in real programs,
but without getting bogged down in details or rules.
At this point, we're not even trying to be complete, or even precise (except
that the examples are meant to be correct).
We want to get you as quickly as possible to the point where you can write
useful programs, and to do that we have to concentrate on the basics: variables
and constants, arithmetic, flow control, functions, and the rudiments of
input and output.
We are intentionally leaving out of this chapter features of Ruamoko that
are important for writing bigger programs, or programs to run in an actual
Quake engine.
These include entities, structures, pointers, most of the operators, objects,
and the standard builtin library.
\layout Standard
This approach has its drawbacks.
Most notable is that the complete story on any particular language feature
is not found here, and the brief tutorial, just by being brief, may be
misleading.
And because the examples don't use the full power of Ruamoko, they may
not be as elegant or concise as they could be; we
\series bold
have
\series default
tried to minimize these effects, but be warned.
Another drawback is that later chapters will repeat some of what's presented
here.
We hope that the repetition will help more than it annoys.
\layout Standard
In any case, experienced programmers should be able to get an idea, from
this chapter, of some of the things that can be done in Ruamoko, for their
own needs.
Beginners should supplement it by writing small, similar programs of their
own.
Both groups can use it as a framework on which to hang the more detailed
descriptions that begin in later chapters.
\layout Section
Getting Started
\layout Standard
The best way to learn a new programming language is by writing programs
in it.
The first program one writes is almost always the same for all new languages:
print the phrase
\begin_inset Quotes eld
\end_inset
Hello, world!
\begin_inset Quotes erd
\end_inset
on the screen.
\layout Standard
This is the big hurdle.
To get past it, you have to be able to create the program text somewhere,
compile it, load it successfully, load it, run it, and find out where the
output went.
With these mechanical details mastered, everything else is relatively easy.
\layout Standard
\begin_inset Float figure
wide false
collapsed true
\layout LyX-Code
\line_top \line_bottom
\begin_inset Include \verbatiminput{hello.r}
preview false
\end_inset
\layout Caption
\begin_inset LatexCommand \label{cap:Hello-World}
\end_inset
\begin_inset Quotes eld
\end_inset
Hello World
\begin_inset Quotes erd
\end_inset
\end_inset
A Ruamoko program that does this simple task is found in Figure
\begin_inset LatexCommand \vref{cap:Hello-World}
\end_inset
.
To run this program, you first have to compile it.
To compile it, you need to save the source code into a file (for example,
\family typewriter
hello.r
\family default
), then compile it with the command
\family typewriter
\series bold
qfcc -o qwaq.dat hello.r
\family default
\series default
.
\layout Standard
If you haven't screwed anything up, such as omitting a character or misspelling
something, the compilation will proceed.
You should be rewarded with something that looks something like Figure
\begin_inset LatexCommand \vref{cap:qfcc-output}
\end_inset
.
\begin_inset Float figure
wide false
collapsed true
\layout LyX-Code
\begin_inset Include \verbatiminput{qfcc-output.txt}
preview false
\end_inset
\layout Caption
\family typewriter
\begin_inset LatexCommand \label{cap:qfcc-output}
\end_inset
\series bold
qfcc
\family default
\series default
output
\end_inset
\layout Standard
You run
\family typewriter
qwaq.dat
\family default
by issuing the command
\family typewriter
\series bold
qwaq
\family default
\series default
.
The program should print
\begin_inset Quotes eld
\end_inset
\family typewriter
Hello, world!
\family default
\begin_inset Quotes erd
\end_inset
to your screen.
\layout Standard
Now, for some explanations regarding the program itself.
All Ruamoko programs, regardless of size, consist mainly of
\emph on
functions
\emph default
and
\emph on
variables
\emph default
.
A function contains statements that tell the compiler what computing operations
you want to do, and variables store values used during the operation of
the program.
Ruamoko functions are roughly equivalent to C's functions, or Pascal's
procedures and functions.
Our example is a function called
\family typewriter
main
\family default
.
You can create functions with just about any name you like, but
\begin_inset Quotes eld
\end_inset
\family typewriter
main
\family default
\begin_inset Quotes erd
\end_inset
is special -- program execution begins there
\begin_inset Foot
collapsed true
\layout Standard
This is not precisely true.
When used in a game engine, there are certain other functions that are
called by the engine during the course of a game.
\end_inset
.
This means that every program must have a
\family typewriter
main
\family default
function somewhere.
\layout Standard
The main function will usually call other functions to do its job -- some
of them you write, and some of them are provided by the virtual machine
your program runs inside.
The first lines of the program (the ones beginning with
\begin_inset Quotes eld
\end_inset
\family typewriter
#include
\family default
\begin_inset Quotes erd
\end_inset
) tell the compiler to include information about the standard variables,
constants,
\emph on
fields
\emph default
\begin_inset LatexCommand \index{fields}
\end_inset
, and
\emph on
engine functions
\begin_inset Foot
collapsed true
\layout Standard
also known as
\emph on
builtins
\emph default
.
\end_inset
\emph default
\begin_inset LatexCommand \index{functions, engine}
\end_inset
provided by the environment
\begin_inset Foot
collapsed true
\layout Standard
The environment will be described later.
\end_inset
.
\layout Standard
One way of communicating data between functions is for the calling function
to provide a list of values, called
\emph on
arguments
\emph default
\begin_inset LatexCommand \index{arguments}
\end_inset
, to the function it calls.
The parentheses after the function's name surround the
\emph on
argument list
\emph default
\begin_inset LatexCommand \index{argument list}
\end_inset
.
In this example, main is defined to be a function that expects no arguments,
which is indicated by an empty list:\SpecialChar ~
\family typewriter
()
\family default
.
\layout Standard
The statements of a function are enclosed in curly braces,\SpecialChar ~
\family typewriter
{}
\family default
.
The function
\family typewriter
main
\family default
contains only one statement,
\family typewriter
printf ("Hello, world!
\backslash
n")
\family default
.
This is a
\emph on
function call
\emph default
, which transfers control from one function to another.
A function is called by giving its name, followed by a list of arguments
enclosed by parentheses, so this calls the function
\family typewriter
printf
\family default
with the argument
\family typewriter
"Hello, world!
\backslash
n"
\family default
.
\family typewriter
printf
\family default
is an engine function that prints output, in this case the string of characters
between the quotes.
\layout Standard
A sequence of characters between double quotes, like
\family typewriter
"Hello, world!
\backslash
n"
\family default
, is called a
\emph on
string constant
\emph default
or simply a
\emph on
string
\emph default
.
For the moment, our only use of strings will be as arguments for
\family typewriter
printf
\family default
and other functions.
\layout Standard
The sequence
\family typewriter
\backslash
n
\family default
in the string is Ruamoko notation for the
\emph on
newline character
\emph default
, which when printed tells the terminal (or a game client) to advance to
the next line in the output.
If you leave out the
\family typewriter
\backslash
n
\family default
, you will find that there is no advance after the character string is printed.
You must use
\family typewriter
\backslash
n
\family default
to include a newline character in the printf argument; if you try to insert
a newline yourself into the string, the Ruamoko compiler will give you
an error message when you compile the program.
\layout Standard
\begin_inset Float figure
wide false
collapsed true
\layout LyX-Code
\line_top \line_bottom
\begin_inset Include \verbatiminput{hello2.r}
preview false
\end_inset
\layout Caption
\begin_inset LatexCommand \label{cap:A-different-Hello}
\end_inset
A different
\begin_inset Quotes eld
\end_inset
Hello World
\begin_inset Quotes erd
\end_inset
\end_inset
The
\family typewriter
printf()
\family default
function never supplies a newline automatically, so several calls may be
used to build up an output line in stages.
Our first program could just as easily been written as it is in figure
\begin_inset LatexCommand \vref{cap:A-different-Hello}
\end_inset
, and it would have produced identical output.
\layout Standard
Note that
\family typewriter
\backslash
n
\family default
represents only a single character.
An
\emph on
escape character
\emph default
like
\family typewriter
\backslash
n
\family default
gives you a general way to express hard-to-type or invisible characters.
Among the others are
\family typewriter
\backslash
t
\family default
for a tab,
\family typewriter
\backslash
b
\family default
for a backspace,
\family typewriter
\backslash
"
\family default
for a double-quote, and
\family typewriter
\backslash
\backslash
\family default
for the backslash character itself.
There is a complete list in [section]
\layout Section
Variables and Mathematical Expressions
\layout Standard
\begin_inset Float figure
wide false
collapsed true
\layout LyX-Code
\line_top \line_bottom
\begin_inset Include \verbatiminput{radians.r}
preview false
\end_inset
\layout Caption
\begin_inset LatexCommand \label{cap:Degrees-to-radians}
\end_inset
Degrees to radians
\end_inset
In figure
\begin_inset LatexCommand \vref{cap:Degrees-to-radians}
\end_inset
, we find a simple program uses the formula
\begin_inset Formula $R=D\,\times\,(\frac{\pi}{180})$
\end_inset
to print a table of various angles in both their degrees and radian equivalents.
\layout Standard
The line
\begin_inset Quotes eld
\end_inset
\family typewriter
/* Print a silly conversion table between degrees and radians */
\family default
\begin_inset Quotes erd
\end_inset
and the three parts that say things like
\begin_inset Quotes eld
\end_inset
\family typewriter
// lower limit
\family default
\begin_inset Quotes erd
\end_inset
are
\emph on
comments
\emph default
\begin_inset LatexCommand \index{comments}
\end_inset
.
Characters between
\family typewriter
/*
\family default
and
\family typewriter
*/
\family default
, and anything between
\family typewriter
//
\family default
and the next line, are ignored by the compiler; they may be used freely
to make a program easier for humans to understand.
Comments may appear anywhere a blank space, or a tab, or a newline can.
\layout Standard
In Ruamoko, all variables must be declared before they are used., usually
at the beginning of the function before any statements.
A declaration
\begin_inset LatexCommand \index{declaration, variable}
\end_inset
announces the properties of variables to the compiler; it consists of a
type name and a list of one or more variables, such as
\layout LyX-Code
float degrees, radians;
\newline
integer lower, upper, step;
\layout Standard
The type
\family typewriter
float
\family default
means that the
\family typewriter
degrees
\family default
and
\family typewriter
radians
\family default
variables are floating-point numbers (numbers that can have a fractional
part), and the type
\family typewriter
integer
\family default
means that the
\family typewriter
lower
\family default
,
\family typewriter
upper
\family default
, and
\family typewriter
step
\family default
variables are integers -- that is, they are whole numbers.
\layout Standard
Unlike C, in which
\family typewriter
int
\family default
and
\family typewriter
float
\family default
can have different sizes depending on the machine, Ruamoko variables always
have a size that is a multiple of 4 bytes (32 bits).
\layout Standard
Ruamoko provides four basic data types
\begin_inset LatexCommand \index{types, basic}
\end_inset
:
\layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="2">
<features>
<column alignment="left" valignment="top" width="0pt">
<column alignment="left" valignment="top" width="0pt">
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\family typewriter
float
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
floating-point numbers
\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\family typewriter
integer
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
whole numbers, with a range between -2147483648 and 2147483647.
\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\family typewriter
string
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
text strings
\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\family typewriter
vector
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
three-dimensional floating-point vectors
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Standard
There are more types than just these four, but this is the list of
\emph on
basic types
\emph default
.
There are also
\emph on
arrays
\emph default
,
\emph on
structures
\emph default
, and
\emph on
unions
\emph default
of these basic types,
\emph on
pointers
\emph default
to them, and functions that return them, all of which we'll meet later.
\layout Standard
The computation in the conversion program begins with the assignment statements
\layout LyX-Code
lower = 0;
\newline
upper = 360;
\newline
step = 45;
\layout Standard
which set the variables to their initial values.
In Ruamoko, as in C, a statement is terminated by the semicolon character.
\layout Standard
Each line of the table is computed in the same manner, so we use a loop
that repeats once per output line; this is the purpose of the
\family typewriter
while
\family default
loop
\layout LyX-Code
while (degrees <= upper) {
\newline
\begin_inset Formula $\vdots$
\end_inset
\newline
}
\layout Standard
The
\family typewriter
while
\family default
loop works like this: The condition in parentheses is tested.
If it is true (if
\family typewriter
degrees
\family default
is less than or equal to
\family typewriter
upper
\family default
), the body of the loop (the three statements enclosed in the block delimited
by the curly braces) is executed.
Then the condition is tested again, and if it's true again, the body is
executed again.
If and when the condition becomes false (
\family typewriter
degrees
\family default
exceeds
\family typewriter
upper
\family default
), the loop ends and execution continues at the statement following the
loop's end.
Since there are no more statements in the program, the end of the loop
terminates the program.
\layout Standard
The body of a while loop can be one or more statements enclosed in braces
(called a block, or compound statement), or a single statement without
braces, as in
\layout LyX-Code
while (i < n)
\newline
i = i * 2;
\layout Standard
In either case, we will always indent the statements controlled by the while
by one tab stop (which we will show as four spaces), so you can see at
a glance which statements are inside the loop.
The indentation emphasizes the logical structure of the program.
The compiler does not care how your program looks, but proper indentation
and spacing are critical in making programs easy for people (including
you) to read.
We recommend writing only one statement per line, and using blanks around
operators to make groupings clear.
The positions of braces is less important, though you should be warned
that many programmers have passionate beliefs about how braces should be
used.
We have chosen the so-called
\begin_inset Quotes eld
\end_inset
One True Brace Style
\begin_inset Quotes erd
\end_inset
, which is the style that Brian Kernighan and Dennis Ritchie used in their
book
\bar under
The C Programming Language
\bar default
, for consistency.
Pick a style that suits you, and use it consistently in your own work,
but be prepared to adapt to the styles of other programmers when writing
as a group.
\layout Standard
Most of the work gets done inside the loop.
The radians for the angle are computed and assigned to the
\family typewriter
radians
\family default
variable using the statement
\layout LyX-Code
radians = degrees * (PI / 180);
\layout Standard
This example also shows a bit more of how
\family typewriter
printf()
\family default
works.
\family typewriter
printf()
\family default
is a general-purpose output formatting function, which we will describe
in detail in [chapter].
Its first argument is a string to be printed, with each
\family typewriter
%
\family default
indicating where one of the other (second, third, and so on) arguments
is to be substituted, and in what form it is to be output.
For instance,
\family typewriter
%f
\family default
specifies a
\family typewriter
float
\family default
argument, so the statement
\layout LyX-Code
printf("%f
\backslash
t%f
\backslash
n", degrees, radians);
\layout Standard
causes the values of the two
\family typewriter
float
\family default
variables
\family typewriter
degrees
\family default
and
\family typewriter
radians
\family default
to be printed, with a tab (
\family typewriter
\backslash
t
\family default
) between them.
\layout Chapter
Types, Operators, and Expressions
\layout Standard
Variables and constants are the basic data units manipulated in a program.
Declarations list the variables to be used, and state what type they have
and perhaps what the initial values for them are.
Operators specify what is to be done to them.
Expressions combine variables and constants to produce new values.
The type of a unit determines the set of values it can have and what operations
are permissible for it.
These building blocks are the subject of this chapter.
\layout Section
Variable Names
\layout Standard
Though we didn't say it in Chapter
\begin_inset LatexCommand \ref{cha:A-Tutorial-Introduction}
\end_inset
, there are some restrictions on variable names and symbolic constants.
Names are composed of letters and digits; the first character must be a
letter (the underscore,
\begin_inset Quotes eld
\end_inset
_
\begin_inset Quotes erd
\end_inset
, counts as a letter -- it's often useful for improving the readability
of long names).
Don't begin variable names with an underscore, however, since functions
beginning with _ are reserved for library and engine functions.
Upper-case and lower-case are distinct, so x and X are two different names.
Traditional practice is to use lower-case or mixed case for variable names,
and all upper-case for
\emph on
symbolic constants
\emph default
, also known as
\emph on
defines
\emph default
.
Keywords like if, else, integer, float, etc.
are reserved -- you can't use them as variable names.
\layout Section
Constants
\layout Standard
An integer constant like
\family typewriter
5678
\family default
is an integer.
Floating-point constants contain a decimal point (
\family typewriter
123.4
\family default
) or an exponent (
\family typewriter
1e-2
\family default
) or both (
\family typewriter
1.2e3
\family default
).
\layout Standard
The value of an integer can be specified in octal (base 8, 0
\begin_inset Formula $\ldots$
\end_inset
7) or hexadecimal (base 16, 0
\begin_inset Formula $\ldots$
\end_inset
F, hereafter called
\begin_inset Quotes eld
\end_inset
hex
\begin_inset Quotes erd
\end_inset
) instead of decimal.
A leading
\family typewriter
0
\family default
(zero) on an integer constant means octal; a leading
\family typewriter
0x
\family default
or
\family typewriter
0X
\family default
means hex.
For example, decimal 31 can be written as
\family typewriter
037
\family default
in octal, or
\family typewriter
0x1f
\family default
or
\family typewriter
0X1F
\family default
in hex.
\layout Standard
Certain characters can be represented in string constants by escape sequences
like
\family typewriter
\backslash
n
\family default
(newline); these sequences look like two characters, but represent only
one.
In addition, an arbitrary byte value can be represented by
\layout LyX-Code
\backslash
o
\layout Standard
where
\family typewriter
o
\family default
is one to three octal digits or by
\layout LyX-Code
\backslash
xh
\layout Standard
where
\family typewriter
h
\family default
is one or more hex digits.
So we might write
\layout LyX-Code
"vtab =
\backslash
013"
\layout Standard
or, in hex,
\layout LyX-Code
"vtab =
\backslash
x0b"
\layout Standard
The complete set of escape sequences is found in Table
\begin_inset LatexCommand \ref{cap:Escape-sequences}
\end_inset
.
\layout Standard
\begin_inset Float table
wide false
collapsed true
\layout Standard
\hfill
\begin_inset Tabular
<lyxtabular version="3" rows="14" columns="2">
<features>
<column alignment="left" valignment="top" leftline="true" width="0pt">
<column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Sequence
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Description
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
a
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Alert (bell) character
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
b
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
backspace
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
f
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
form feed
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
n
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
newline
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
r
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
carriage return
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
t
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
tab character
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
\backslash
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
backslash
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
?
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
question mark
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
'
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
single quote
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
"
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
double quote
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
ooo
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
octal number
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
xhh
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
hex number
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\backslash
^
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
alternate character set (toggles)
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\hfill
\layout Caption
\begin_inset LatexCommand \label{cap:Escape-sequences}
\end_inset
Escape sequences
\end_inset
\layout Chapter
Control Constructs: Kneel Before Zod
\layout Chapter
Arrays and Pointers: Pull Pin, Then Throw
\bar under
GRENADE
\layout Chapter
Breaking Up The Program: Now Where Did I Put That?
\layout Part
Object-Oriented Programming in Ruamoko
\layout Part
Language Reference
\layout Chapter
Types
\layout Standard
This is currently just new stuff in
\family typewriter
\series bold
qfcc
\family default
\series default
.
\layout Section
New Type Features
\layout Subsection
New Types
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
integer
\family default
32 bit signed integer
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
id
\family default
generic object pointer
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
Class
\family default
class object pointer
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
Protocol
\family default
protocol object pointer
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
Method
\family default
method pointer
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
SEL
\family default
selector
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
IMP
\family default
message implementation
\layout Standard
\family typewriter
id
\family default
,
\family typewriter
Class
\family default
,
\family typewriter
Protocol
\family default
,
\family typewriter
Method
\family default
,
\family typewriter
SEL
\family default
and
\family typewriter
IMP
\family default
are part of
\family typewriter
\series bold
qfcc
\family default
\series default
's Objective-QC extensions.
\layout Subsection
Enumerators
\layout Standard
as per C
\layout Subsection
Structures
\layout LyX-Code
struct foo {
\newline
integer bar;
\newline
float baz;
\newline
void () func;
\newline
};
\layout Standard
Structures with no elements can be declared for making opaque types (particularl
y useful for engine interface functions).
\layout Subsection
Arrays
\layout LyX-Code
integer [13] array;
\layout Subsection
Pointers
\layout Standard
Pointers are declared the same way as arrays, but with no number in the
\family typewriter
[]
\family default
s.
In fact, arrays are just pointers with limited (compile-time) bounds checking
(constant indices).
\layout Subsection
Complex types
\layout Standard
Complex types can be created by nesting type declarations within
\family typewriter
()
\family default
s.
e.g.:
\layout LyX-Code
(.float) (string name) find_field;
\layout Standard
declares a function (
\family typewriter
find_field
\family default
) taking a string parameter and returning a float field `offset'.
Without the
\family typewriter
()
\family default
s around the
\family typewriter
.float
\family default
, the declaration would be a function field.
\layout Subsection
\family typewriter
typedef
\layout Standard
By using
\family typewriter
typedef
\family default
complex types can be given symbolic names.
e.g.:
\layout LyX-Code
struct foo_s {};
\newline
typedef foo_s [] foo_t;
\layout Standard
creates type
\family typewriter
foo_t
\family default
which is a pointer to the structure
\family typewriter
foo_s
\family default
(which happens to be opaque).
\layout Subsection
Variable-argument functions
\layout Standard
Typed parameters preceding the ellipsis are allowed, e.g.:
\family typewriter
void (string fmt, \SpecialChar \ldots{}
) printf;
\layout Standard
More importantly, it is now possible to write vararg functions in QC.
\family typewriter
@argc
\family default
gives the number of parameters passed through the ellipsis and
\family typewriter
@argv
\family default
is an array of vectors representing the parameters passed through
\family typewriter
\SpecialChar \ldots{}
\family default
.
\layout Standard
\series bold
\emph on
Warning: attempting to pass
\family typewriter
@argv
\family default
to a non-engine function will not work.
This is because of changes in how local variables are handled by the compiler.
\layout Subsection
Improved type checking
\layout Standard
Function parameters and return types are are fully checked, including the
number of parameters passed to a function.
Functions with different return types and/or different parameter types
or counts are distinct types and mixing them up will cause a type mismatch
error.
Similar for pointers to various types.
\layout Section
Variables
\layout Subsection
Local variables
\layout Subsubsection
Initialization
\layout Standard
Local variables of basic types can now be initialized when declared.
e,g,
\layout Verse
\family typewriter
local integer elite = 31337;
\layout Subsubsection
Unused variables
\layout Standard
Local variables that are declared but not used produce a warning.
\layout Subsubsection
Uninitialized variables
\layout Standard
Checks are done to ensure that local variables have been initialized before
being used.
However, these checks are not perfect and false positives are very likely
in complex code.
Occurrences of false negatives are not known, but the possibility of their
existence remains and any examples of false negatives should be reported
as bugs.
\layout Subsection
Complex global variables
\layout Standard
Global array variables can be initialized using
\family typewriter
= {
\emph on
element-list
\emph default
};
\family default
.
Element lists may be nested using
\family typewriter
{}
\family default
.
Structures cannot currently be initialized, but this is a FIXME :)
\layout Subsection
Magic variables
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
@self
\family default
Automagically-declared entity variable the engine will use for
\family typewriter
touch
\family default
and
\family typewriter
think
\family default
functions.
This allows
\family typewriter
self
\family default
to be used as the object hidden parameter in methods.
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
@this
\family default
Automagically-declared
\family typewriter
id
\family default
field that the engine expects to point to the object associated with the
entity.
The engine will use this field, if it exists, to set the
\family typewriter
self
\family default
parameter to
\family typewriter
touch
\family default
and
\family typewriter
think
\family default
methods (the engine assumes it's calling a method rather than a function
if the @this field is used.
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
@argc
\family default
Number of parameters passed through
\family typewriter
\SpecialChar \ldots{}
\family default
in vararg functions.
Not valid elsewhere.
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
@argv
\family default
Array of vectors representing the parameters passed through
\family typewriter
\SpecialChar \ldots{}
\family default
in vararg functions.
Not valid elsewhere.
\layout Section
Code constructs
\layout Subsection
\family typewriter
break
\layout Standard
The
\family typewriter
break
\family default
statement can be used to leave a loop (
\family typewriter
while
\family default
,
\family typewriter
do
\family default
\SpecialChar \ldots{}
\family typewriter
while
\family default
, or
\family typewriter
for
\family default
) prematurely.
The
\family typewriter
break
\family default
statement is also used to leave a
\family typewriter
switch
\family default
statement.
\layout Subsection
\family typewriter
continue
\layout Standard
The
\family typewriter
continue
\family default
statement is used to jump to the beginning of a loop.
In
\family typewriter
for
\family default
loops, the test and post expressions are evaluated before continuing with
the loop.
\layout Subsection
\family typewriter
for
\layout Standard
The
\family typewriter
for
\family default
loop is:
\layout LyX-Code
for (
\emph on
initialization-expression
\emph default
;
\emph on
test-expression
\emph default
;
\emph on
post-expression
\emph default
)
\layout LyX-Code
\emph on
statement
\layout Standard
and is equivalent to
\layout LyX-Code
\emph on
initialization expression
\layout LyX-Code
while (
\emph on
test expression
\emph default
) {
\layout LyX-Code
\emph on
statement
\layout LyX-Code
\emph on
post expression
\layout LyX-Code
}
\layout Subsection
\family typewriter
switch
\layout Standard
The
\family typewriter
switch
\family default
statement is used to select between multiple code blocks based on the value
of an expression.
\layout LyX-Code
switch (
\emph on
test expression
\emph default
) {
\newline
case
\emph on
value
\emph default
:
\newline
\emph on
optional statements
\newline
\emph default
case
\emph on
value
\emph default
:
\newline
\emph on
optional statements
\emph default
\newline
default:
\newline
\emph on
optional statements
\emph default
\newline
}
\layout Standard
Code execution starts at the selected
\family typewriter
case
\family default
and continues on to the end of the switch block.
Following
\family typewriter
case
\family default
s do
\emph on
not
\emph default
affect code execution.
If this behavior is not desired, as is usual, then a
\family typewriter
break
\family default
statement is required to cause the code to jump to the end of the
\family typewriter
switch
\family default
, skipping any intervening code.
That is, just like C.
\layout Subsubsection
\family typewriter
\emph on
test expression
\layout Standard
The test expression may result in a float, string or integer value.
\layout Subsubsection
\family typewriter
case
\emph on
value
\layout Verse
\family typewriter
case
\emph on
value
\emph default
:
\layout Standard
The case value may be of any constant type consistent with the test expression
of the
\family typewriter
switch
\family default
.
\layout Subsubsection
\family typewriter
default
\layout Standard
If specified, this is where execution will go when no
\family typewriter
case
\family default
has been selected by the test expression.
If not specified, and no
\family typewriter
case
\family default
has been selected by the test expression, the
\family typewriter
switch
\family default
does not execute any code within the block.
\layout Section
Expressions
\layout Subsection
Binary
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
<<\SpecialChar ~
>>
\family default
bit shift left and right
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
^
\family default
bitwise exclusive or
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
%
\family default
modulus
\layout Subsubsection
Assignment
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
\emph on
op
\emph default
=
\family default
equivalent to
\family typewriter
a = a
\emph on
op
\emph default
b
\family default
.
\layout Subsection
Unary
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
~
\family default
bitwise not
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
&
\family default
address
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
++
\emph on
e
\emph default
\SpecialChar ~
--
\emph on
e
\family default
\emph default
pre-increment and decrement
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
\emph on
e
\emph default
++\SpecialChar ~
\emph on
e
\emph default
--
\family default
post-increment and decrement
\layout Subsection
Other
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
\emph on
type\SpecialChar ~
\emph default
(
\emph on
expr
\emph default
)
\family default
cast expression.
Works only for converting between integer and float types and between pointer
types.
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
\emph on
expr
\emph default
[
\emph on
expr
\emph default
]
\family default
array indexing.
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
\emph on
expr
\emph default
?
\emph on
expr
\emph default
:
\emph on
expr
\family default
\emph default
C's trinary expression
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
[
\emph on
expr
\emph default
\SpecialChar ~
\emph on
exprs
\emph default
]
\family default
Objective-QC message
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
@selector(
\emph on
exprs
\emph default
)
\family default
Objective-QC selector expression
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
@protocol(
\emph on
name
\emph default
)
\family default
Objective-QC protocol expression
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
@encode(
\emph on
type
\emph default
)
\family default
Objective-QC type encoding expression
\layout Labeling
\labelwidthstring 00.00.0000
\family typewriter
@
\emph on
string
\family default
\emph default
Objective-QC string object.
Currently identical to a normal QC string.
\layout Standard
\begin_inset LatexCommand \printindex{}
\end_inset
\the_end
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