Library Reference

version 2.112.0

Internal API

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dmd.root.optional

Implementation of an 'Optional' type

Authors:

Walter Bright

License:

Boost License 1.0

Sourceroot/optional.d

Documentationhttps://dlang.org/phobos/dmd_root_optional.html

Coveragehttps://codecov.io/gh/dlang/dmd/src/master/compiler/src/dmd/root/optional.d

Examples:

import core.exception : AssertError;Optional!int opt;assert( opt.isEmpty());assert(!opt.isPresent());assert(!opt.hasValue(1));assert(!opt.hasValue(2));bool caught;trycast(void) opt.get();catch (AssertError)    caught =true;assert(caught);opt = Optional!int(1);assert(!opt.isEmpty());assert( opt.isPresent());assert( opt.get() == 1);assert( opt.hasValue(1));assert(!opt.hasValue(2));

structOptional(T);

Optional type that is eitherempty or contains a value of typeT

this(Tvalue); static Optional!Tcreate(Tval);: Creates anOptional with the given value
boolisPresent() const;: Returns:
Whether thisOptional contains a value
boolisEmpty() const;: Returns:
Whether thisOptional does not contain a value
inout(T)get() inout;: Returns:
The value if present
boolhasValue(const Texp) const;: Returns:
Whether thisOptional contains the supplied value

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Library Reference

dmd.root.optional