[slime-devel] Re: SBCL restart-frame

[Mészáros Levente]

>   levy> On the other hand return from frame is already supported for 
SBCL
> in
>   levy> SLIME.
> 
>   levy> And if I got it right the above statement also means that 
return
> from
>   levy> frame works the same "somewhat bad" way. I mean 
returning from the
>   levy> frame of bar (in the debugger) the value of *a* will return 1
> instead of
>   levy> 0.
> 
>   levy> Am I right?
> 
> Yes.  However, there are two environments here:
> 
> 1) The environment used to compute arguments for the command.  
Possibly
> this
>    should be the environment of the frame, but it doesn't matter too 
much
> as
>    long as the person debugging the code knows which environment 
is used.
> 
> 2) The environment used to execute the command.  For "restart 
frame", this
>    should be the original environment of the frame, otherwise 
functions
> like
>    FOO will fail to perform correctly.  For "return from frame" it doesn't
>    really matter which environment is used, becase no user code is
> executed.
> 
> __Martin

I see your points, but the last statement I think is not quite true. 
Return from the frame can evaluate an expression which might or might 
not refer to user code. Actually it is very usefull to call the original 
function with different parameters for example. In which case the 
environment problem still exists. Of course if one is aware of that then 
the issue can be safely avoided.

levy

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