ANSI Common Lisp   9 Conditions   9.1 Condition System Concepts   9.1.4 Signaling and Handling Conditions

9.1.4.2 Restarts

A restart contains a function to be called when the restart is invoked, an optional name that can be used to find or invoke the restart, and an optional set of interaction information for the debugger to use to enable the user to manually invoke a restart.

The name of a restart is used by invoke-restart. Restarts that can be invoked only within the debugger do not need names.

Restarts can be established by using restart-bind, restart-case, and with-simple-restart. A restart function can itself invoke any other restart that was active at the time of establishment of the restart of which the function is part.

The restarts established by a restart-bind form, a restart-case form, or a with-simple-restart form have dynamic extent which extends for the duration of that form's execution.

Restarts of the same name can be ordered from least recent to most recent according to the following two rules:

• 1. Each restart in a set of active restarts R₁ is more recent than every restart in a set R₂ if the restarts in R₂ were active when the restarts in R₁ were established.

• 2. Let r₁ and r₂ be two active restarts with the same name established by the same form. Then r₁ is more recent than r₂ if r₁ was defined to the left of r₂ in the form that established them.

If a restart is invoked but does not transfer control, the values resulting from the restart function are returned by the function that invoked the restart, either invoke-restart or invoke-restart-interactively.

9.1.4.2.1  Interactive Use of Restarts
9.1.4.2.2  Interfaces to Restarts
9.1.4.2.3  Restart Tests
9.1.4.2.4  Associating a Restart with a Condition