# Equiv

### Related Docs: object Equiv | package math

#### trait Equiv[T] extends Serializable

A trait for representing equivalence relations. It is important to distinguish between a type that can be compared for equality or equivalence and a representation of equivalence on some type. This trait is for representing the latter.

An equivalence relation is a binary relation on a type. This relation is exposed as the `equiv` method of the `Equiv` trait. The relation must be:

1. reflexive: `equiv(x, x) == true` for any x of type `T`.
2. symmetric: `equiv(x, y) == equiv(y, x)` for any `x` and `y` of type `T`.
3. transitive: if `equiv(x, y) == true` and `equiv(y, z) == true`, then `equiv(x, z) == true` for any `x`, `y`, and `z` of type `T`.
Source
Equiv.scala
Version

1.0, 2008-04-03

Since

2.7

Linear Supertypes
Serializable, java.io.Serializable, Any
Ordering
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2. By inheritance
Inherited
1. Equiv
2. Serializable
3. Serializable
4. Any
Implicitly
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc
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Visibility
1. Public
2. All

### Abstract Value Members

1. #### abstract def equiv(x: T, y: T): Boolean

Returns `true` iff `x` is equivalent to `y`.

2. #### abstract def getClass(): Class[_]

Returns the runtime class representation of the object.

Returns the runtime class representation of the object.

returns

a class object corresponding to the runtime type of the receiver.

Definition Classes
Any

### Concrete Value Members

1. #### final def !=(arg0: Any): Boolean

Test two objects for inequality.

Test two objects for inequality.

returns

`true` if !(this == that), false otherwise.

Definition Classes
Any
2. #### final def ##(): Int

Equivalent to `x.hashCode` except for boxed numeric types and `null`.

Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

returns

a hash value consistent with ==

Definition Classes
Any
3. #### def +(other: String): String

Implicit information
This member is added by an implicit conversion from Equiv[T] to any2stringadd[Equiv[T]] performed by method any2stringadd in scala.Predef.
Definition Classes
4. #### def ->[B](y: B): (Equiv[T], B)

Implicit information
This member is added by an implicit conversion from Equiv[T] to ArrowAssoc[Equiv[T]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
()
5. #### final def ==(arg0: Any): Boolean

Test two objects for equality.

Test two objects for equality. The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

returns

`true` if the receiver object is equivalent to the argument; `false` otherwise.

Definition Classes
Any
6. #### final def asInstanceOf[T0]: T0

Cast the receiver object to be of type `T0`.

Cast the receiver object to be of type `T0`.

Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

returns

Definition Classes
Any
Exceptions thrown

`ClassCastException` if the receiver object is not an instance of the erasure of type `T0`.

7. #### def ensuring(cond: (Equiv[T]) ⇒ Boolean, msg: ⇒ Any): Equiv[T]

Implicit information
This member is added by an implicit conversion from Equiv[T] to Ensuring[Equiv[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
8. #### def ensuring(cond: (Equiv[T]) ⇒ Boolean): Equiv[T]

Implicit information
This member is added by an implicit conversion from Equiv[T] to Ensuring[Equiv[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
9. #### def ensuring(cond: Boolean, msg: ⇒ Any): Equiv[T]

Implicit information
This member is added by an implicit conversion from Equiv[T] to Ensuring[Equiv[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
10. #### def ensuring(cond: Boolean): Equiv[T]

Implicit information
This member is added by an implicit conversion from Equiv[T] to Ensuring[Equiv[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
11. #### def equals(arg0: Any): Boolean

Compares the receiver object (`this`) with the argument object (`that`) for equivalence.

Compares the receiver object (`this`) with the argument object (`that`) for equivalence.

Any implementation of this method should be an equivalence relation:

• It is reflexive: for any instance `x` of type `Any`, `x.equals(x)` should return `true`.
• It is symmetric: for any instances `x` and `y` of type `Any`, `x.equals(y)` should return `true` if and only if `y.equals(x)` returns `true`.
• It is transitive: for any instances `x`, `y`, and `z` of type `AnyRef` if `x.equals(y)` returns `true` and `y.equals(z)` returns `true`, then `x.equals(z)` should return `true`.

If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override `hashCode` to ensure that objects which are "equal" (`o1.equals(o2)` returns `true`) hash to the same scala.Int. (`o1.hashCode.equals(o2.hashCode)`).

returns

`true` if the receiver object is equivalent to the argument; `false` otherwise.

Definition Classes
Any
12. #### def formatted(fmtstr: String): String

Returns string formatted according to given `format` string.

Returns string formatted according to given `format` string. Format strings are as for `String.format` (@see java.lang.String.format).

Implicit information
This member is added by an implicit conversion from Equiv[T] to StringFormat[Equiv[T]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
()
13. #### def hashCode(): Int

Calculate a hash code value for the object.

Calculate a hash code value for the object.

The default hashing algorithm is platform dependent.

Note that it is allowed for two objects to have identical hash codes (`o1.hashCode.equals(o2.hashCode)`) yet not be equal (`o1.equals(o2)` returns `false`). A degenerate implementation could always return `0`. However, it is required that if two objects are equal (`o1.equals(o2)` returns `true`) that they have identical hash codes (`o1.hashCode.equals(o2.hashCode)`). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the `equals` method.

returns

the hash code value for this object.

Definition Classes
Any
14. #### final def isInstanceOf[T0]: Boolean

Test whether the dynamic type of the receiver object is `T0`.

Test whether the dynamic type of the receiver object is `T0`.

Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

returns

`true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

Definition Classes
Any
15. #### def toString(): String

Returns a string representation of the object.

Returns a string representation of the object.

The default representation is platform dependent.

returns

a string representation of the object.

Definition Classes
Any
16. #### def →[B](y: B): (Equiv[T], B)

Implicit information
This member is added by an implicit conversion from Equiv[T] to ArrowAssoc[Equiv[T]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc