Smalltalk and Object Orientation: an Introduction - Free

Select the “Debug” option. This wil l open a debugger on the error code. Now select the second line
down in the top window. This should start with optimized []. The debugger with this line selected
is illustrated below:
In the top scrollable window of the debugger you see each method whi ch has been executed, in the
window below this, you see the source code relating to the method. In this case you see a “decompiled”
version of the code you wrote in the Workspace displayed. It is decompiled because you typed the
original code into the Workspace rather than into a class. It therefore had no class to refer back to. You
will know decompiled code from original source code for two reasons. Firstly, there will be a comment
telling you that it has been decompiled and secondly the variables will ha ve names such as t1 and t2
rather than the variable names you chose.
In the debugger you can identify the point at which the error was caused because it will be
highlighted. That is, the message “show” will be in bold. You can correct the error by changing “show”
to “show:”.
You could now fix the problem here (and when you are debugging methods on actual classes you
may well do so). However, there is no point doing so this time, as this is the decompiled version of your
original. Thus any changes you make here will be lost once this run is completed (in addition the item
following show has not been compiled yet and therefore remains as item where as the temporary
variable at the beginning of the do: statement has been decompiled to t2 - rather t han item). It would
therefore be better to go back to the Workspace and fix it there.
You should change the show statement to read:
temp do: [:item | Transcript show: item]
Now select all the code and “do it” again. This time the contents of the set shou ld be printed in the
Transcript.
Notice that the order in which you input the strings may differ from the order in which they are
printed. This is due to the way add: works (why not have a look and see for yourself).
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