debugger? (was: Re: prototypes vs classes was: Re: Sun's HotSpot)

David Stes stes at
Fri Oct 16 10:38:58 UTC 1998

On Thu, 15 Oct 1998, Dan Ingalls wrote:

> 1.  Execute 'self halt', or hit cmd-. to get into a debugger.
> 2.  Select some method with temps on the stack.
>     Let us assume one is called 'zort'.

 I see some methods with temp variables like 't1' etc.

 There's no zort.
> 3.  In the code pane or bottomRight inspector pane, type and execute...
> 	self halt.  zort + 3
>      This will bring up a second debugger.

 You mean: self halt. t1 + 3

> 4.  Select the method 'DoItIn:' on the stack.  This is what was compiled from what you typed.  It will be decompiled, and should look very much like:
>     DoItIn: t1 
>         self halt.
>         ^ (t1 tempAt: 1) + 3


> 5.  In this situation, the simple variable reference (zort) is compiled to
>     a message (t1 tempAt: 1) for the purpose of accessing a remote
>     temporary variable.  You can probably guess the result of doing...
> 	self halt.  zort := 3

  That would be something like  ^ t1 tempAt: 1 put: 3.

  Ah, now I see! The 't1' that is argument of the DoItIn: message is not 
related to the 't1' of the original method.

  O.K., now I see why you call the original temporary variable "zort".  I
was sort of confused by the "zort". 

  Thanks for explaining this.

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