Many languages allow you to extract values from objects into variables. C# 7.0 introduces a new syntax for this called deconstruction which is similar in other ways.

This support is automatic for deconstructing from record and DictionaryEntry types however other types require a Deconstruct method to be defined either directly on the type or as an extension method ^{C# 3.0}.

Code

Now

void ProcessShipment(Shipment shipment)
{
    var (tracking, country, postCode) = shipment;

    // ...
}

Before

void ProcessShipment(Shipment shipment)
{
    var tracking = shipment.tracking;
    var country = shipment.Country;
    var postCode = shipment.PostCode;

    /// ...
}

Notes

• You can either:
  • Use the var keyword to infer all the types from the deconstruction
  • Declare the types inline with the deconstruction individually (int tracking, string country, var postCode) = shipment;
  • Assign the values directly to existing variables (tracking, country, postCode) = shipment;
• Declaration and assignment can be mixed in C# 10

More information

• Deconstructing tuples and other types
• Playing with C# 7 Deconstruct @ Adam Storr