vtkAssume.h File Reference

#include "vtkConfigure.h"
#include <cassert>

Include dependency graph for vtkAssume.h:

Go to the source code of this file.

Macros
#define	VTK_ASSUME(cond)
	VTK_ASSUME instructs the compiler that a certain non-obvious condition will always be true. More...
#define	VTK_ASSUME_IMPL(cond)   do {} while (false) /* no-op */

Macro Definition Documentation

#define VTK_ASSUME

(

cond

)

Value:

do { \
  const bool c = cond; \
  assert("Bad assumption in VTK_ASSUME: " #cond && c); \
  VTK_ASSUME_IMPL(c); \
  (void)c; /* Prevents unused var warnings */ \
  } while (false) /* do-while prevents extra semicolon warnings */

VTK_ASSUME instructs the compiler that a certain non-obvious condition will always be true.

Beware that if cond is false at runtime, the results are unpredictable (and likely catastrophic). A runtime assertion is added so that debugging builds may easily catch violations of the condition.

A useful application of this macro is when a vtkGenericDataArray subclass has a known number of components at compile time. Adding, for example, VTK_ASSUME(array->GetNumberOfComponents() == 3); allows the compiler to provide faster access through the GetTypedComponent method, as the fixed data stride in AOS arrays allows advanced optimization of the accesses.

A more detailed description of this class and related tools can be found here.

Definition at line 42 of file vtkAssume.h.

#define VTK_ASSUME_IMPL

(

cond

)

do {} while (false) /* no-op */

Definition at line 59 of file vtkAssume.h.