Display the source code in std/variant.d from which this page was generated on github.

If you spot a problem with this page, click here to create a Bugzilla issue.

Quickly fork, edit online, and submit a pull request for this page. Requires a signed-in GitHub account. This works well for small changes. If you'd like to make larger changes you may want to consider using local clone.

Class `std.variant.VariantException`

Thrown in three cases:


						
				class VariantException
				
  : Exception
				;

An uninitialized Variant is used in any way except assignment and hasValue;
A get or coerce is attempted with an incompatible target type;
A comparison between Variant objects of incompatible types is attempted.

Fields

Name	Type	Description
`source`	`TypeInfo`	The source type in the conversion or comparison
`target`	`TypeInfo`	The target type in the conversion or comparison
`file`	`string`	The file name of the D source code corresponding with where the error was thrown from.
`info`	`object.Throwable.TraceInfo`	The stack trace of where the error happened. This is an opaque object that can either be converted to `string`, or iterated over with `foreach` to extract the items in the stack trace (as strings).
`line`	`ulong`	The line number of the D source code corresponding with where the error was thrown from.
`msg`	`string`	A message describing the error.

Properties

Name	Type	Description
`next`[get]	`inout(Throwable)`
`next`[set]	`Throwable`	Replace next in chain with `tail`. Use `chainTogether` instead if at all possible.

Methods

Name	Description
`chainTogether` ()	Append `e2` to chain of exceptions that starts with `e1`.
`factory` (classname)	Create instance of class specified by the fully qualified name classname. The class must either have no constructors or have a default constructor.
`message` ()	Get the message describing the error. Base behavior is to return the `Throwable.msg` field. Override to return some other error message.
`opApply` (dg)	Loop over the chain of Throwables.
`opCmp` (o)	Compare with another Object obj.
`opEquals` (o)	Test whether `this` is equal to `o`. The default implementation only compares by identity (using the `is` operator). Generally, overrides and overloads for `opEquals` should attempt to compare objects by their contents. A class will most likely want to add an overload that takes your specific type as the argument and does the content comparison. Then you can override this and forward it to your specific typed overload with a cast. Remember to check for `null` on the typed overload.
`refcount` ()
`toHash` ()	Compute hash function for Object.
`toString` ()	Overrides `Object.toString` and returns the error message. Internally this forwards to the `toString` overload that takes a sink delegate.
`toString` ()	The Throwable hierarchy uses a toString overload that takes a sink delegate to avoid GC allocations, which cannot be performed in certain error situations. Override this `toString` method to customize the error message.

Example

import std.exception : assertThrown;

Variant v;

// uninitialized use
assertThrown!VariantException(v + 1);
assertThrown!VariantException(v.length);

// .get with an incompatible target type
assertThrown!VariantException(Variant("a").get!int);

// comparison between incompatible types
assertThrown!VariantException(Variant(3) < Variant("a"));

Authors

Andrei Alexandrescu

License

Boost License 1.0.