Printing Stack Trace on Caught Exception

[Michael Forzano]

Hi All,

As far as I know, there is no way to get the traceback of a caught
exception (as is possible in nearly every other language). Am I wrong?
If not, has anyone created a patch to do this?

Mike

[Josh Benner]

That is incorrect.

You can specify a variable in the except statement that includes traceback information.

My code will feature things like this:

try

  ... code ...

except e (ANY)

  if (player.wizard)

    player:tell_lines($dev_utils:format_caught_error(e));

  endif

  ... other remediation ...

endtry

Here is my $dev_utils:format_caught_error (expects ANSI):

{input} = args;

{error, msg, val, traceback} = input;

su = $string_utils;

name = this:debug_name(traceback[1][4]);

out = {su:message_text({"[bold][red]", toliteral(error), "[normal]: ", msg, " in [bold][yellow]", name, "[white]:[red]", traceback[1][2], "[white], line [green]", traceback[1][6], "[normal] (this == [bold][cyan]", traceback[1][1], "[normal])"}, #2)};

first = 1;

for call in (`traceback[2..$] ! ANY => {}')

  {_this, _verb, _prog, _verb_loc, _player, _line} = call;

  loc = this:debug_name(_verb_loc);

  out = {@out, su:message_text({"... called from [bold][yellow]", loc, "[white]:[red]", _verb, "[normal] (this == [bold][cyan]", _this, "[normal]), line [bold][green]", _line}, #2)};

endfor

out = {@out, "(end of traceback)"};

return out;

$dev_utils:debug_name() just outputs an object literal or a $-literal if one exists on #0 for the object in question. I don't recall if message_text is in Lambda or not... it's basically just a way to to output lists including non-string values to format them better than just their literal representations (ie: show obj name and ref).

-- 

Josh Benner

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[Jason SW]

try
"Normal stuff";
except tb (ANY|MOO error code)
"catch stuff";
endtry
Is this what you need? Or did you already know about this?