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Template std.variant.tryVisit
Behaves as visit
but doesn't enforce that all types are handled
by the visiting functions.
template tryVisit(Handlers...)
;
If a parameter-less function is specified it is called when
either variant
doesn't hold a value or holds a type
which isn't handled by the visiting functions.
Contained Functions
Name | Description |
---|---|
tryVisit |
Returns
The return type of tryVisit is deduced from the visiting functions and must be the same across all overloads.
Throws
VariantException
if variant
doesn't hold a value or
variant
holds a value which isn't handled by the visiting functions,
when no parameter-less fallback function is specified.
Example
Algebraic!(int, string) variant;
variant = 10;
auto which = -1;
variant .tryVisit!((int i) { which = 0; })();
writeln(which); // 0
// Error function usage
variant = "test";
variant .tryVisit!((int i) { which = 0; },
() { which = -100; })();
writeln(which); // -100
Authors
License
Copyright © 1999-2022 by the D Language Foundation | Page generated by ddox.