Stack traces: Difference between revisions

=={{header|Oz}}==

System exceptions contain the current stack at the nested feature <code>debug.stack</code>. For example:

<lang oz>declare

proc {Test}

_ = 1 div 0

end

in

try

{Test}

catch E then

{Inspect E}

end</lang>

Output:

[[File:Oz_stacktrace1.png|center|Stack trace of a system exception in Oz.]]

To have such a stack trace in custom exceptions, either indicate this by throwing a record value with a <code>debug:unit</code> feature or use the [http://www.mozart-oz.org/documentation/base/exception.html Exception] module to create exceptions.

To access the stack trace directly, you can use the undocumented internal Debug module. Its <code>getTaskStack</code> function takes a thread, a depth value and a boolean "verbose" flag. It returns a list of stack frames. Example:

<lang oz>%% make sure that simple function calls are not optimized away

\switch +controlflowinfo

declare

[Debug] = {Link ['x-oz://boot/Debug']}

proc {F} {G} end

proc {G} {H} end

proc {H}

{Inspect {Debug.getTaskStack {Thread.this} 100 true}}

end

in

{F}</lang>

Output:

[[File:Oz_stacktrace2.png|center|Stack trace created by the Debug module.]]