Criticism
This pattern should be used carefully as it can make errors/bugs appear as normal program execution.
Care should be taken not to implement this pattern just to void null checks and make code more readable, since the harder to read code may just move to another place and be less standard - such as when different logic must execute in case the object provided is indeed the Null Object. For the common pattern in most languages with reference types is to compare a reference to a single value referred to as null or nil. Also, there is additional need for testing that no code anywhere ever assigns null instead of the Null Object, because in most cases and languages with static typing, this is not a compiler error if the Null Object is of a reference type, although it would certainly lead to errors at run time in parts of the code where the pattern was used to avoid null checks. On top of that, in most languages and assuming there can be many Null Objects (i.e. the Null Object is a reference type but doesn't implement the Singleton pattern in one or another way), checking for the Null Object instead of for the null or nil value introduces overhead, as does the singleton pattern likely itself upon obtaining the singleton reference.
Read more about this topic: Null Object Pattern
Famous quotes containing the word criticism:
“To be just, that is to say, to justify its existence, criticism should be partial, passionate and political, that is to say, written from an exclusive point of view, but a point of view that opens up the widest horizons.”
—Charles Baudelaire (1821–1867)
“The critic lives at second hand. He writes about. The poem, the novel, or the play must be given to him; criticism exists by the grace of other men’s genius. By virtue of style, criticism can itself become literature. But usually this occurs only when the writer is acting as critic of his own work or as outrider to his own poetics, when the criticism of Coleridge is work in progress or that of T.S. Eliot propaganda.”
—George Steiner (b. 1929)
“Parents sometimes feel that if they don’t criticize their child, their child will never learn. Criticism doesn’t make people want to change; it makes them defensive.”
—Laurence Steinberg (20th century)