ArcGIS Engine Developer Guide

VISUAL C++
method, use the smart pointer “&” dereference operator. This will cause the
previous interface pointer in the smart pointer to be released. The smart pointer is
then populated with the new [out] value. The implementation of the method will
have already incremented the object reference count. This will be released when
the smart pointer goes out of scope:
{
IFooPtr ipFoo1, ipFoo2;
ipFoo1.CreateInstance(CLSID_Foo);
ipFoo2.CreateInstance(CLSID_Foo);
// Initialize ipBar Smart pointer from Foo1.
IBarPtr ipBar;
ipFoo1->get_Bar(&ipBar);
// The "&" dereference will call Release on ipBar.
// ipBar is then repopulated with a new instance of IBar.
ipFoo2->get_Bar(&ipBar);
}
// ipBar goes out of scope, and the smart pointer destructor calls Release.
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 a separate line:
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);
Chapter 4 • Developer environments • 115