Object attributes
Attributes may be used to retrieve information about an object or an expression. For expression X:
| X'size | returns the number of bits in X |
| X'msb | returns the value of the most significant bit of X |
| X'meta | returns true if X contains metadata, and false otherwise |
| X'offset | returns the offset of X, in bits, when X is an array element or structure member. If X evaluates to a stream, it instead returns the current location in that stream |
| X'last | returns a previous value of the operand |
These attributes are actually postfix operators, and their use is therefore not restricted to objects. They may be used anywhere where a postfix operator is allowable.