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Hope for C Programmers

Unfortunately, some embedded projects won't have a C++ compiler, or the CPU selection will preclude the use of C++. Yet, even in these circumstances, you don't necessarily have to abandon object-oriented programming principles. For example, in your public functions, you can mandate that the caller pass in a handle (a this pointer) returned from a simulated constructor function. This technique permits other functions to access class-specific resources that are invisible to external parties (see Listings 1 and 2). Although this trick isn't as elegant or as flexible as a true C++ class, it will let you model object-oriented concepts.

Listing 1 A Typical C++ Class

class Blob

{
void getBlobInfo( int attribute, int *pGetInfo);
void setBlobInfo( int attribute, int setInfo);
} ;

Listing 2 illustrates how C can model the C++ Blob class methods in Listing 1. The newBlob() function (or simulated constructor) returns a handle (this pointer) that's required for all related functions in that API set.

Listing 2 Modeling the Listing 1 Class in C

typedef void * BlobHandle;

BlobHandle newBlob( void );
void deleteBlob( BlobHandle );

void getBlobInfo( BlobHandle handle, int attribute, int *pGetInfo);
void setBlobInfo( BlobHandle handle, int attribute, int setInfo);
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