in reply to How to tell eval where the code is from

You probably would find it best to use Carp, test @_ after the eval, and if it is set then confess to the problem.

In the confess you can name the function.

BTW don't use confess if you don't think that a stack backtrace would be helpful. Personally I do surprisingly often but YMMV.

  • Comment on Re: How to tell eval where the code is from

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RE: Re: How to tell eval where the code is from
by Yaakov (Novice) on Aug 08, 2000 at 15:56 UTC
    Thank you very much for your help.

    I am still stuck with AUTOLOADed routines: When the routine is called the first time, AUTOLOAD executes a statement like

    $code=$database{$AUTOLOAD}; # e.g: "sub pkg::foo {...}"
eval $code; 
$@ and error_msg($AUTOLOAD, $@, $code);
goto &$AUTOLOAD;

    [download]

    This code catches compilation errors. But when the routine is actually called later, the variable $@ is no longer active.

    Also, warnings (like those for undefined values) are generated without giving the running code an opportunity to add some information.

[reply]
[d/l]
      Inside your eval, add something like: 
      $code = $database{$AUTOLOAD};
$pseudo_file = get_pseudo_for($AUTOLOAD); # like "Database_entry_for_p
+kg::foo"
eval qq{#line 1 "$pseudo_file"\n$code};
...

      [download]
      Now when an error triggers, you'll get 
      whatever error from Database_entry_for_pkg::foo, line 14

      [download]
      in $@ Use the cpp triggers, luke!

      -- Randal L. Schwartz, Perl hacker

[reply]
[d/l]
[select]
        Thank you very much. This solves my problem.

        I would much appreciate a source reference where I could have found that information myself. I bet I find other interesting things there, too.

        Yaakov

[reply]
      I thought of this after I posted.

      I actually think that your original approach is the right idea, wrong syntax. A better approach probably would be to provide a second optional argument to eval() that is the name to call this error.

      In any case I suggest that you sign up for the perl5-porters list, state your problem, state your proposed solution, and see if you cannot get it accepted. Possibly with the syntax I am recommending. Possibly with some better syntax that they think of.

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