710      "evaluate the argument, aBlock.

   710     "evaluate the argument, aBlock.

   711       If the receiver-signal is raised during evaluation, abort

   711      If the receiver-signal is raised during evaluation, abort

   712       the evaluation and return true; otherwise return false. 

   712      the evaluation and return true; otherwise return false. 

   713       This is the catch & throw mechanism found in other languages,

   713      This is the catch & throw mechanism found in other languages,

   714       where the returned value indicates if an exception occured."

   714      where the returned value indicates if an exception occured."

   715 

   715 

   716       |raiseOccurred|

   716      |raiseOccurred|

   717 

   717 

   718       raiseOccurred := false.

   718      raiseOccurred := false.

   719       self handle:[:ex | raiseOccurred := true. ex return] do:aBlock.

   719      self handle:[:ex | raiseOccurred := true. ex return] do:aBlock.

   720       ^ raiseOccurred

   720      ^ raiseOccurred

   721 

   721 

   722       "

   722      "

   723        Object messageNotUnderstoodSignal catch:[

   723       Object messageNotUnderstoodSignal catch:[

   724           123 size open   

   724          123 size open   

   725        ]

   725       ]

   726       "

   726      "

   727 !

   728 

   729 deferAfter:aBlock

   730     "evaluate the argument, aBlock.

   731      Ignore the receiver-signal during evaluation - i.e. simply continue,

   732      but remember if the signal was raised.

   733      After the block evaluation, finally raise the signal - if it was raised in the block.

   734      If the signal is raised multiple times, only the first raises parameter is remembered,

   735      and only a single raise is performed after the blocks evaluation.

   736 

   737      Deferring makes sense for some signals, such as UserInterrupt or AbortSignal, 

   738      which must occasionally be delayed temprarily until a save place is reached 

   739      (especially when packages are sent across a communication channel, and you dont want

   740       partial packages to be generated by user interruptions)."

   741 

   742     |raisedSignal parameter result|

   743 

   744     self handle:[:ex |

   745         raisedSignal isNil ifTrue:[

   746             raisedSignal := ex signal.

   747             parameter := ex parameter.

   748         ].

   749         ex proceedWith:nil

   750     ] do:[

   751         result := aBlock value.

   752     ].

   753     raisedSignal notNil ifTrue:[

   754         "/ the signal was raised during the execution

   755         "/ above. Raise it now (delayed).

   756         raisedSignal raiseWith:parameter.

   757     ].

   758     ^ result

   759 

   760      "

   761       UserInterrupt deferAfter:[

   762          UserInterrupt raiseWith:'hello'

   763       ]

   764      "

   809      "evaluate the argument, aBlock.

   847     "evaluate the argument, aBlock.

   810       Ignore the receiver-signal during evaluation - i.e. simply continue. 

   848      Ignore the receiver-signal during evaluation - i.e. simply continue. 

   811       This makes only sense for some signals, such as UserInterrupt

   849      This makes only sense for some signals, such as UserInterrupt

   812       or AbortSignal, because continuing after an exception without any cleanup

   850      or AbortSignal, because continuing after an exception without any cleanup

   813       often leads to followup-errors."

   851      often leads to followup-errors."

   814 

   852 

   815       ^ self handle:[:ex | ex proceedWith:nil] do:aBlock.

   853      ^ self handle:[:ex | ex proceedWith:nil] do:aBlock.

   816 

   854 

   817       "

   855      "

   818        Object messageNotUnderstoodSignal ignoreIn:[

   856       Object messageNotUnderstoodSignal ignoreIn:[

   819           123 size open   

   857          123 size open   

   820        ]

   858       ]

   821       "

   859      "

   827     ^ '$Header: /cvs/stx/stx/libbasic/Signal.st,v 1.85 2001-11-16 15:18:54 cg Exp $'

   865     ^ '$Header: /cvs/stx/stx/libbasic/Signal.st,v 1.86 2002-02-15 12:59:12 cg Exp $'

   828 ! !

   866 ! !