Default case
A default case is the switch or select execution path chosen when no other eligible case matches or can be selected.
Learn Concurrent Programming with Go
A default case is the select branch that executes immediately when no other channel communication case is ready.
- How it is used
- Enables non-blocking channel attempts and lets concurrent computations continue until another channel signals completion.
- How deep it goes
- Explains selection behavior, demonstrates polling, and applies it to cancellable goroutines; it stops short of implementation internals.
- Examples
- Uses a delayed message loop and a parallel password search stopped through a closed channel.
- What you can do after
- Apply it via Go's select statement to poll channels or keep workers responsive to cancellation.
Read how Learn Concurrent Programming with Go explains default case →
100 Go Mistakes and How to Avoid Them
A default case is a select or switch clause chosen when no other eligible case can be selected.
- How it is used
- Uses default to drain currently available channel messages without blocking after a disconnection.
- How deep it goes
- Explains selection semantics, nested draining, nondeterministic readiness, and the boundary where later messages are missed.
- Examples
- Uses messageCh and disconnectCh to trace disconnection handling, remaining-message delivery, and default-case return.
- What you can do after
- Apply nested select logic to consume ready messages and terminate without blocking when a channel is temporarily empty.
Read how 100 Go Mistakes and How to Avoid Them explains default case →
Related concepts
- select statementpart of · A select statement is a language construct that retrieves selected data or chooses among alternative operations or cases according to the language's rules.
- when expressionalternative to · A when expression is a Kotlin multi-branch conditional expression that selects a result by matching conditions or a subject value against alternatives.
- default valuecontrasts with · A default value is a predefined or automatically supplied value used when an expected input, argument, field, or configuration setting is omitted or unspecified.
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