In computer programming, an opaque predicate is a predicate—an expression that evaluates to either "true" or "false"—for which the outcome is known by the programmer a priori, but which, for a variety of reasons, still needs to be evaluated at run time. Opaque predicates have been used as watermarks, as it will be identifiable in a program's executable. They can also be used to prevent an overzealous optimizer from optimizing away a portion of a program. Another use is in obfuscating the control or dataflow of a program in order to make reverse engineering harder.
Famous quotes containing the words opaque and/or predicate:
“... people were so ridiculous with their illusions, carrying their fools’ caps unawares, thinking their own lies opaque while everybody else’s were transparent, making themselves exceptions to everything, as if when all the world looked yellow under a lamp they alone were rosy.”
—George Eliot [Mary Ann (or Marian)
“The predicate of truth-value of a proposition, therefore, is a mere fictive quality; its place is in an ideal world of science only, whereas actual science cannot make use of it. Actual science instead employs throughout the predicate of weight.”
—Hans Reichenbach (1891–1953)