Hi Thomas, Hi Max, On Thu, Mar 21, 2019 at 3:35 AM Max Leske <maxleske@gmail.com> wrote:
On 21 Mar 2019, at 11:06, Thomas Dupriez wrote:
Hi Thomas,
Hello,
While looking at the DebugSession>>isContextPostMortem: method (code below), I got three questions:
1) There is a check for whether the suspendedContext (top context) of the process is nil. Does it even make sense for a process not to have any top context?
Yes, only suspended processes have a suspendedContext. Also, the process might have been terminated already.
2) It seems that all the last 3 lines are doing is to check whether selectedContext is in the context chain of the process. Could they be rewritten into this simpler one-liner? `|^ (suspendedContext hasContext: selectedContext) not`|
Yes, I think that would work.
3) Overall, this method says that a context C is "post mortem" if the process controlled by the DebugSession has a top context and C is not in its context chain. That's the practical definition. Could someone shed some light on the high-level definition of "post mortem"? Because "post mortem" is like "after death", but the death of what? A context that merely belongs to another context chain would be considered "post mortem" by the practical definition, but there's no death in this case... ||
You can create a copy of a process' stack. That stack will behave like a process in the debugger but it can't run, as the VM doesn't have a process to which the context are attached, hence it's considered post-mortem.
```
|DebugSession>>isContextPostMortem: selectedContext "return whether we're inspecting a frozen exception without a process attached" | suspendedContext | suspendedContext := interruptedProcess suspendedContext. suspendedContext ifNil: [ ^ false ]. (suspendedContext == selectedContext) ifTrue: [ ^ false ]. ^ (suspendedContext findContextSuchThat: [:c | c sender == selectedContext]) isNil ``` |
In addition a context is post-mortem if its pc is nil, which at least in Squeak is answered by the Context>>isDead method. So I might look at writing that method as DebugSession>>isContextPostMortem: selectedContext "Answer if we're inspecting a frozen exception without a process attached." ^selectedContext isDead or: [(interruptedProcess suspendedContext hasContext: selectedContext) not]
Does someone know the answer to some (or all) of these questions?
Thomas
Hope that helps.
Max
-- _,,,^..^,,,_ best, Eliot