code_generation.h File Reference

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Macros
#define	STMT(STMT_code__)   do { STMT_code__; } while(false)
	package code into a single statement. More...
#define	ONCE(ONCE_code__)
	execute the code passed as a parameter only the first time this is reached. More...
#define	ONCE_NOT(ONCE_code__)
	execute the code passed as a parameter except the first time this is reached. More...
#define	AT_STARTUP(code__)
	execute the code passed as a parameter before main is entered. More...
#define	SAFE_NEW(type, ptr)
	C++ new wrapper: allocates an instance of the given type and stores a pointer to it. More...
#define	SAFE_DELETE(p)
	delete memory ensuing from new and set the pointer to zero (thus making double-frees safe / a no-op) More...
#define	SAFE_ARRAY_DELETE(p)
	delete memory ensuing from new[] and set the pointer to zero (thus making double-frees safe / a no-op) More...
#define	SAFE_FREE(p)
	free memory ensuing from malloc and set the pointer to zero (thus making double-frees safe / a no-op) More...

Macro Definition Documentation

AT_STARTUP

#define AT_STARTUP

(

code__

)

Value:

    namespace { struct UID__\
    {\
        UID__() { code__; }\
    } UID2__; }

execute the code passed as a parameter before main is entered.

WARNING: if the source file containing this is not directly referenced from anywhere, linkers may discard that object file (unless linking statically). see http://www.cbloom.com/3d/techdocs/more_coding.txt

ONCE

#define ONCE

(

ONCE_code__

)

Value:

STMT(\
    static bool ONCE_done__ = false;\
    if(!ONCE_done__)\
    {\
        ONCE_done__ = true;\
        ONCE_code__;\
    }\
)

execute the code passed as a parameter only the first time this is reached.

may be called at any time (in particular before main), but is not thread-safe. if that's important, use std::call_once instead.

ONCE_NOT

#define ONCE_NOT

(

ONCE_code__

)

Value:

STMT(\
    static bool ONCE_done__ = false;\
    if(!ONCE_done__)\
        ONCE_done__ = true;\
    else\
        ONCE_code__;\
)

execute the code passed as a parameter except the first time this is reached.

may be called at any time (in particular before main), but is not thread-safe.

SAFE_ARRAY_DELETE

#define SAFE_ARRAY_DELETE

(

p

)

Value:

STMT(\
    delete[] (p);   /* if p == 0, delete is a no-op */ \
    (p) = 0;\
)

delete memory ensuing from new[] and set the pointer to zero (thus making double-frees safe / a no-op)

SAFE_DELETE

#define SAFE_DELETE

(

p

)

Value:

STMT(\
    delete (p); /* if p == 0, delete is a no-op */ \
    (p) = 0;\
)

delete memory ensuing from new and set the pointer to zero (thus making double-frees safe / a no-op)

SAFE_FREE

#define SAFE_FREE

(

p

)

Value:

STMT(\
    free((void*)p); /* if p == 0, free is a no-op */ \
    (p) = 0;\
)

free memory ensuing from malloc and set the pointer to zero (thus making double-frees safe / a no-op)

SAFE_NEW

#define SAFE_NEW	(		type,
			ptr
	)

Value:

    type* ptr;\
    try\
    {\
        ptr = new type();\
    }\
    catch(std::bad_alloc&)\
    {\
        ptr = 0;\
    }

C++ new wrapper: allocates an instance of the given type and stores a pointer to it.

sets pointer to 0 on allocation failure.

this simplifies application code when on VC6, which may or may not throw/return 0 on failure.

STMT

#define STMT

(

STMT_code__

)

do { STMT_code__; } while(false)

package code into a single statement.

Parameters

STMT_code__

code to be bundled. (must be interpretable as a macro argument, i.e. sequence of tokens). the argument name is chosen to avoid conflicts.

notes:

• for(;;) { break; } and {} don't work because invocations of macros implemented with STMT often end with ";", thus breaking if() expressions.
• we'd really like to eliminate "conditional expression is constant" warnings. replacing 0 literals with extern volatile variables fools VC7 but isn't guaranteed to be free of overhead. we will just squelch the warning (unfortunately non-portable).