Expected

Expected!(T, E) is a type that represents either success or failure.

Type T is used for success value. If T is void, then Expected can only hold error value and is considered a success when there is no error value.

Type E is used for error value. The default type for the error value is string.

Default behavior of Expected can be modified by the Hook template parameter.

struct Expected (

T

E = string

Hook = Abort

) if (

!is(E == void) &&

(

isVoidValueEnabled!Hook ||

!is(T == void)

)

) {

import core.lifetime : forward;;

import std.meta : AliasSeq, Filter, NoDuplicates;;

import std.traits : isAssignable, isCopyable, hasIndirections, Unqual;;

this(E val, bool success);

static if(isDefaultConstructorEnabled!Hook)
static if(isAssignable!CT)

void opAssign(CT rhs);

static if(!isChecked!Hook)

bool opCast();

static if(!(!isChecked!Hook))

bool opCast();

static if(!is(T == void))
static if(!isChecked!Hook)

bool opEquals(T rhs);

static if(!is(T == void))
static if(!(!isChecked!Hook))

bool opEquals(T rhs);

static if(!isChecked!Hook)

bool opEquals(Expected!(T, E, Hook) rhs);

static if(!(!isChecked!Hook))

bool opEquals(Expected!(T, E, Hook) rhs);

static if(!isChecked!Hook)

size_t toHash();

static if(!(!isChecked!Hook))

size_t toHash();

static if(!is(T == void))
static if(!isChecked!Hook)

bool hasValue [@property getter];

static if(!is(T == void))
static if(!(!isChecked!Hook))

bool hasValue [@property getter];

static if(!is(T == void))
static if(!isChecked!Hook)

inout(T) value [@property getter];

static if(!is(T == void))
static if(!(!isChecked!Hook))

T value [@property getter];

static if(!isChecked!Hook)

bool hasError [@property getter];

static if(!(!isChecked!Hook))

bool hasError [@property getter];

static if(!isChecked!Hook)

inout(E) error [@property getter];

static if(!(!isChecked!Hook))

E error [@property getter];

static if(!is(T == void))
static if(!isChecked!Hook)

bool empty [@property getter];

static if(!is(T == void))
static if(!isChecked!Hook)

inout(T) front [@property getter];

static if(!is(T == void))
static if(!(!isChecked!Hook))

bool empty [@property getter];

static if(!is(T == void))
static if(!(!isChecked!Hook))

T front [@property getter];

static if(!is(T == void))

void popFront();

}

Constructors

this this(CT val): Constructs an Expected with value or error based on the tye of the provided.
this this(E val, bool success): Constructs an Expected with value or error based on the provided flag. This constructor is available only for cases when value and error has the same type, so we can still construct Expected with value or error.
this this(): Undocumented in source.

Destructor

~this ~this(): Undocumented in source.

Postblit

this(this) this(this): Undocumented in source.

Members

Functions

opAssign void opAssign(CT rhs): Assigns a value or error to an Expected.
opCast bool opCast(): Implicit conversion to bool.
opEquals bool opEquals(T rhs): Checks whether this Expected object contains a specific expected value.
opEquals bool opEquals(Expected!(T, E, Hook) rhs): Checks whether this Expected object and rhs contain the same expected value or error value.
popFront void popFront(): Range interface defined by empty, front, popFront. Yields one value if Expected has value.
toHash size_t toHash(): Calculates the hash value of the Expected in a way that iff it has a value, it returns hash of the value. Hash is computed using internal state and storage of the Expected otherwise.

Properties

empty bool empty [@property getter]: Range interface defined by empty, front, popFront. Yields one value if Expected has value.
empty bool empty [@property getter]: Undocumented in source. Be warned that the author may not have intended to support it.
error inout(E) error [@property getter]: Returns the error value. May only be called when hasValue returns false.
error E error [@property getter]: Undocumented in source. Be warned that the author may not have intended to support it.
front inout(T) front [@property getter]
T front [@property getter]: Range interface defined by empty, front, popFront. Yields one value if Expected has value.
hasError bool hasError [@property getter]: Checks if Expected has error
hasValue bool hasValue [@property getter]: Checks if Expected has value
value inout(T) value [@property getter]: Returns the expected value if there is one.
value T value [@property getter]: Undocumented in source. Be warned that the author may not have intended to support it.

Parameters

T: represents type of the expected value
E: represents type of the error value.
Hook: defines the Expected type behavior

Meta

Source

See Implementation