6.128 Signal

Defined in namespace Smalltalk

Category: Language-Exceptions

My instances describe an exception that has happened, and are passed to exception handlers. Apart from containing information on the generated exception and its arguments, they contain methods that allow you to resume execution, leave the #on:do:... snippet, and pass the exception to an handler with a lower priority.

6.128.1 Signal: accessing		(instance)
6.128.2 Signal: exception handling		(instance)

6.128.1 Signal: accessing

argument

Answer the first argument of the receiver

argumentCount

Answer how many arguments the receiver has

arguments

Answer the arguments of the receiver

basicMessageText

Answer an exception's message text. Do not override this method.

description

Answer the description of the raised exception

exception

Answer the CoreException that was raised

messageText

Answer an exception's message text.

messageText: aString

Set an exception's message text.

tag

Answer an exception's tag value. If not specified, it is the same as the message text.

tag: anObject

Set an exception's tag value. If nil, the tag value will be the same as the message text.

6.128.2 Signal: exception handling

defaultAction

Execute the default handler for the raised exception

isNested

Answer whether the current exception handler is within the scope of another handler for the same exception.

isResumable

Answer whether the exception that instantiated the receiver is resumable.

outer

Raise the exception that instantiated the receiver, passing the same parameters. If the receiver is resumable and the evaluated exception action resumes then the result returned from #outer will be the resumption value of the evaluated exception action. If the receiver is not resumable or if the exception action does not resume then this message will not return, and #outer will be equivalent to #pass.

pass

Yield control to the enclosing exception action for the receiver. Similar to #outer, but control does not return to the currently active exception handler.

resignalAs: replacementException

Reinstate all handlers and execute the handler for `replacementException'; control does not return to the currently active exception handler. The new Signal object that is created has the same arguments as the receiver (this might or not be correct -- if it isn't you can use an idiom such as `sig retryUsing: [ replacementException signal ])

resume

If the exception is resumable, resume the execution of the block that raised the exception; the method that was used to signal the exception will answer the receiver. Use this method IF AND ONLY IF you know who caused the exception and if it is possible to resume it in that particular case

resume: anObject

If the exception is resumable, resume the execution of the block that raised the exception; the method that was used to signal the exception will answer anObject. Use this method IF AND ONLY IF you know who caused the exception and if it is possible to resume it in that particular case

retry

Re-execute the receiver of the #on:do: message. All handlers are reinstated: watch out, this can easily cause an infinite loop.

retryUsing: aBlock

Execute aBlock reinstating all handlers, and return its result from the #signal method.

return

Exit the #on:do: snippet, answering anObject to its caller

return: anObject

Exit the #on:do: snippet, answering anObject to its caller