[Help-smalltalk] Exception Handling

[Jerry Mead]

Smalltalk users --

I am having the following problem -- and I think it might be as a
result of my not understanding how CoreException interface.

The attached smalltalk program lets me test how CoreExceptions
work.  The first line adds an exception object to Smalltalk.  As is
the exception has 'isResumable' set to 'true'.  In this form the program,
when executed gives the following output:

-----------------------------------------
st> FileStream fileIn:'testExc.st'!
st> (Test new: 9) doit!
6
'too big'
5
-----------------------------------------


which seems to me what should happen.  After the exception is
handled, execution resumes just after the exception occurred.

Now if the file is modified so that 'isResumable' is set to
'false', I get the following result:

-----------------------------------------
st> FileStream fileIn:'testExc.st'!
st> (Test new: 9) doit!
6
'too big'
Object: MethodContext new: 8 "<0x601982f8>" error: did not understand 
#thisContext
MethodContext(Object)>>#primError:
MessageNotUnderstood(Exception)>>#defaultAction
[] in Exception class>>#coreException
MessageNotUnderstood(Signal)>>#activateHandler:
MessageNotUnderstood(Exception)>>#signal
MethodContext(Object)>>#doesNotUnderstand:
Signal>>#activateHandler:
CoreException>>#signal
Obj>>#try:
[] in Test>>#doit
BlockClosure>>#on:do:
Test>>#doit
UndefinedObject>>#executeStatements
-----------------------------------------

If someone can help me with this I will be most grateful.

Jerry Mead

______________________________________________________________________
Jerry Mead, Assoc Prof        email:  address@hidden
Computer Science Department   URL:    http://www.eg.bucknell.edu/~mead
Bucknell University
Lewisburg, PA 17837

Smalltalk at:#exc put: ((CoreException new) isResumable: false)!

Object subclass: #Obj
       instanceVariableNames: 'val'
       classVariableNames: ''
       poolDictionaries: ''
       category: nil!

!Obj class methodsFor: 'initialization'!

new: v
    |o|
    o := self new.
    o init: v.
    ^o
!!

!Obj methodsFor: 'initialization'!

init: v
    val := v
!

try: v
    (v < val) ifTrue: [ v printNl ]
              ifFalse: [ exc signal ]
!!



Object subclass: #Test
       instanceVariableNames: 'this val'
       classVariableNames: ''
       poolDictionaries: ''
       category: nil!

!Test class methodsFor: 'initialization'!

new: v
    |o|
    o := self new.
    o init: v.
    ^o
!!

!Test methodsFor: 'initialization'!

init: v
    val := v
!

doit
  this := Obj new: val.
  [
    this try: 6.
    this try: 10.
    this try: 5
  ] on: exc do: [:x| 'too big' printNl ]
!!