Volatile means evaporating readily at normal temperatures and pressures, i e , capable of being readily vaporized
From the C keyword Used throughout the source and in discussion, signifying a variable or inline asm that cannot be optimised as usual by the compiler This usually means the compiler shouldn't store the variable in a register, as another task can alter the value of the real memory contents at the time For example, this is necessary with I/O address spaces, where the hardware device can fill up a buffer asynchronously to a reading task Variables which are changed from both interrupts and other contexts are also volatile
An immutable object is said to be volatile if it has components that cannot be modified by the programmer at the protocol level, but which may be modified internally by CLIM Volatile objects reflect the internal state of CLIM