Chapter 1

Category Examples Description
Static classes User, Math, Mem,
ConeUtils
inheritance in Symbian OS;
they act similarly to
interfaces in Java. The
old technical term
was'mixin', hence the use of
M.
A class consisting purely of
static functions that can't
be instantiated into an
object Such classes are
useful containers of library
functions.
Structs SEikControlInfo A C-style struct, without
any member functions.
There are only a few of
these inSymbian OS; most
later code uses T classes
even for structs.
Some other prefixes are occasionally used for classes, in rare circumstances. The only one
we'll encounter in this book is HBufC, for heap-based descriptors. Kernel-side programming
uses D for kernel-side CBase-derived classes.
The distinction between T, C, and R is very important in relation to cleanup properties, which
I'll cover in detail in Chapter 6.
Lastly, always ensure that class names are nouns: classes are for objects, not actions.
CBase-derived classes should not be allocated on the stack as automatics. The zero
initialization will not work, so the class may not behave as expected. These classes are
designed exclusively to be used on the heap; their behavior is undefined if used in a stack
context. There are also situations in Symbian OS in which the destructor of an object may
not be called. The methods used to resolve all this assume that the object is heap-based. To
prevent this situation, most CBase classes have private constructors that are called from
standard static functions (generally called NewL or NewLC).
3.2.2 Data Names
These also use an initial letter, excepting automatics.
Category Examples Description
Enumerated constant EMonday,
ESolidBrush
Constants in an enumeration. If it has
a name at all, the enumeration itself
should have a T prefix, so that
EMonday is a member of
TDayOfWeek.When we cover
resource files, we'll also find some
#defined constants use an E prefix in
circumstances in which the constants
belong to a logically distinct set.