Interface Equivalence

A strategy for determining whether two values are considered equivalent.

It is important to distinguish between a type that can be compared for equality and a representation of an equivalence relation. This interface is for representing the latter, while PhpCommon\Comparison\Equatable is for representing the former.

For the purpose of this interface, an equivalence relation is a binary relation that is reflexive, symmetric, transitive and consistent. Additionally, an equivalence relation can be either generic or type-specific. The "equals" relation is an example of a generic relation. Type-specific examples include:

"Has the same birthday as" on the set of all people.
"Is similar to" or "congruent to" on the set of all triangles.
"Has the same absolute value" on the set of real numbers.

Consult the documentation of the specific PhpCommon\Comparison\Equivalence implementation for more information about the supported types.

It is inspired by the Equivalence interface, from Guava API.

PhpCommon\Comparison\Equivalence implements PhpCommon\Comparison\Equatable

Direct known implementers

PhpCommon\Comparison\Equivalence\GenericEquivalence, PhpCommon\Comparison\Hasher

Indirect known implementers

PhpCommon\Comparison\Hasher\DateTimeHasher, PhpCommon\Comparison\Hasher\GenericHasher, PhpCommon\Comparison\Hasher\IdentityHasher, PhpCommon\Comparison\Hasher\ValueHasher

Namespace: PhpCommon\Comparison
Author: Marcos Passos marcos@marcospassos.com
Link: Guava Equivalent interface
Located at Equivalence.php

Methods summary
`public boolean`	# `equivalent( mixed $left, mixed $right )` Checks whether the specified values are considered equivalent. Checks whether the specified values are considered equivalent. This method has the following properties: It is reflexive: for any `$x`, including `null`, `equivalent($x, $x)` returns `true`. It is symmetric: for any `$x` and `$y`, `equivalent($x, $y) === equivalent($y, $x)`. It is transitive: for any references `$x`, `$y`, and `$z`, if `equivalent($x, $y)` returns `true` and `equivalent($y, $z)` returns `true`, then `equivalent($x, $z)` returns `true`. It is consistent: for any `$x` and `$y`, multiple invocations of `equivalent($x, $y)` consistently return `true` or consistently return `false` (provided that neither `$x` nor `$y` is modified). Parameters `$left` The left-hand value to compare. `$right` The right-hand value to compare. Returns boolean Returns `true` if the given values are considered equivalent, `false` otherwise. Throws `PhpCommon\Comparison\UnexpectedTypeException` If the type of the left-hand side does not match the expected type. `PhpCommon\Comparison\IncomparableException` If the given values are not comparable under the specified equivalence relation. Link Equivalence relation

Methods inherited from PhpCommon\Comparison\Equatable
`equals()`

Namespaces

Interfaces

Exceptions

Interface Equivalence

Direct known implementers

Indirect known implementers

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Throws

Link