DynamicVariable
DynamicVariables provide a binding mechanism where the current
value is found through dynamic scope, but where access to the
variable itself is resolved through static scope.
DynamicVariables provide a binding mechanism where the current
value is found through dynamic scope, but where access to the
variable itself is resolved through static scope.
The current value can be retrieved with the value method. New values
should be pushed using the withValue method. Values pushed via
withValue only stay valid while the withValue's second argument, a
parameterless closure, executes. When the second argument finishes,
the variable reverts to the previous value.
someDynamicVariable.withValue(newValue) {
// ... code called in here that calls value ...
// ... will be given back the newValue ...
}Each thread gets its own stack of bindings. When a
new thread is created, the DynamicVariable gets a copy
of the stack of bindings from the parent thread, and
from then on the bindings for the new thread
are independent of those for the original thread.