Книга: Standard Template Library Programmer
Predicate
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Predicate
Category: functors
Component type: concept
Description
A Predicate is a Unary Function whose result represents the truth or falsehood of some condition. A Predicate might, for example, be a function that takes an argument of type int and returns true if the argument is positive.
Refinement of
Unary Function
Associated types
| Result type | The type returned when the Predicate is called. The result type must be convertible to bool. |
Notation
F A type that is a model of Predicate
X The argument type of F
f Object of type F
x Object of type X
Valid expressions
| Name | Expression | Return type |
|---|---|---|
| Function call | f(x) |
Convertible to bool |
Expression semantics
| Name | Expression | Precondition | Semantics | Postcondition |
|---|---|---|---|---|
| Function call | f(x) |
x is in the domain of f. | Returns true if the condition is satisfied, false if it is not. | The result is either true or false. |
Models
• bool (*)(int)
See also
Adaptable Predicate, Binary Predicate, Adaptable Binary Predicate
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