ArcGIS Engine Developer Guide

C++ APPLICATION PROGRAMMING INTERFACE
Here are some suggestions for a naming
convention. These help identify the variable’s
usage and type and thus reduce coding errors.
This is an abridged Hungarian notation:
Prefix
m
c
g
Prefix
b
by
cx/cy
d
dw
f
fn
h
i
ip
l
p
s
sz
w
x, y
[_]
Variable scope
Instance class members
Static class member (including constants)
Globally static variable
local variable or struct or public class
member
Data Type
Boolean
byte or unsigned char
short used as size
double
DWORD, double word or unsigned long
float
function
handle
int (integer)
smart pointer
long
a pointer
string
ASCIIZ null-terminated string
WORD unsigned int
short used as coordinates
describes how the variable is used or
what it contains. The and
portions should always be lowercase, and the
should use mixed case:
Variable Name
m_hWnd
ipEnvelope
m_pUnkOuter
c_isLoaded
g_pWindowList
Description
a handle to HWND
a smart pointer to a COM interface
a pointer to an object
a static class member
a global pointer to an object
Naming conventions
Type names
All type names (class, struct, enum, and typedef) begin with an uppercase letter and
use mixed case for the rest of the name:
class Foo : public CObject { . . .};
struct Bar { . . .};
enum ShapeType { . . . };
typedef int* FooInt;
Typedefs for function pointers (callbacks) append Proc to the end of their names.
typedef void (*FooProgressProc)(int step);
Enumeration values all begin with a lowercase string that identifies the project; in
the case of ArcObjects this is esri, and each string occurs on separate lines:
typedef enum esriQuuxness
{
esriQLow,
esriQMedium,
esriQHigh
} esriQuuxness;
Function names
Name functions using the following conventions:
For simple accessor and mutator functions, use Get and
Set:
int GetSize();
void SetSize(int size);
If the client is providing storage for the result, use Query:
void QuerySize(int& size);
For state functions, use Set and Is or Can:
bool IsFileDirty();
void SetFileDirty(bool dirty);
bool CanConnect();
Where the semantics of an operation are obvious from the types of arguments,
leave type names out of the function names.
Instead of:
AddDatabase(Database& db);
consider using:
Add(Database& db);
Instead of:
ConvertFoo2Bar(Foo* foo, Bar* bar);
consider using:
Convert(Foo* foo, Bar* bar)
If a client relinquishes ownership of some data to an object, use
Give. If an object relinquishes ownership of some data to a client,
use Take:
Chapter 4 • Developer environments • 201