Maybe

Constructors

this

this(T value)

Constructing Maybe from value. If pointer is null methods: isNothing returns true and get throws Error.

Members

Aliases

StoredType

alias StoredType = T

Alias to stored type

Functions

get

T get()

Unwrap value from Maybe. If stored value is null, Error is thrown.

get

const(T) get()

Unwrap value from Maybe. If stored value is null, Error is thrown.

isNothing

bool isNothing()

Returns true if stored value is null

map

U map(U delegate() nothingCase, U delegate(T) justCase)

If struct holds null, then nothingCase result is returned. If struct holds not null value, then $(justCase) result is returned. justCase is fed with unwrapped value.

map

U map(U delegate() nothingCase, U delegate(const T) justCase)

If struct holds null, then nothingCase result is returned. If struct holds not null value, then $(justCase) result is returned. justCase is fed with unwrapped value.

Static functions

nothing

Maybe!T nothing()

Constructing empty Maybe. If Maybe is created with the method, it is considred empty and isNothing returns false.

1 class A {}
2 
3 auto a = new A();
4 auto ma = Maybe!A(a);
5 auto mb = Maybe!A(null);
6 
7 assert(!ma.isNothing);
8 assert(mb.isNothing);
9 
10 assert(ma.get == a);
11 assertThrown!Error(mb.get);
12 
13 bool ncase = false, jcase = false;
14 ma.map(() {ncase = true;}, (v) {jcase = true;});
15 assert(jcase && !ncase);
16 
17 ncase = jcase = false;
18 mb.map(() {ncase = true;}, (v) {jcase = true;});
19 assert(!jcase && ncase);

• Maybe