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Re: $var = do { ... }?

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Martijn Lievaart <m@rtij.nl.invlalid> writes:
> On Fri, 02 Mar 2012 20:43:17 +0000, Rainer Weikusat wrote:
>
>> Ben Morrow <ben@morrow.me.uk> writes:
>
>>> If you insist on doing the eval yourself, you should test the truth of
>>> the eval
>>>
>>>     eval {
>>>         ...
>>>     } or do {
>>>         ...
>>>     };
>>>
>>> rather than relying on $@,
>> 
>> No, I shouldn't "always do this" because I usually know what the code
>> will be doing when executed, ie, in this case, that there are neither
>
> If there is a clear way that is always correct and another equally clear 
> way that may break on refactoring, I always would choose the first. This 
> seems like one of those cases (which I didn't know about yet btw).

Testing $@ is 'always correct' while the return value of eval might be
'false' for any number of reasons because it is just the return value
of the last thing executed in the scope of the eval.

----------
my $bc;

my $rc = eval {
	$bc = 3;
	die('huh?') if $bc != 3;
} or do {
	print("Ben Morrow error occurred!\n");
	$@ or print("Phew ... that was close ... \n");
};
----------

Also, there is no way to write code such that yet unknown future
changes made to this code are guaranteed to be correct.

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Thread

$var = do { ... }? tmcd@panix.com (Tim McDaniel) - 2012-03-02 17:15 +0000
  Re: $var = do { ... }? merlyn@stonehenge.com (Randal L. Schwartz) - 2012-03-02 09:52 -0800
  Re: $var = do { ... }? Shmuel (Seymour J.) Metz <spamtrap@library.lspace.org.invalid> - 2012-03-02 13:42 -0500
  Re: $var = do { ... }? Ben Morrow <ben@morrow.me.uk> - 2012-03-02 18:44 +0000
    Re: $var = do { ... }? tmcd@panix.com (Tim McDaniel) - 2012-03-02 19:00 +0000
      Re: $var = do { ... }? merlyn@stonehenge.com (Randal L. Schwartz) - 2012-03-02 11:45 -0800
      Re: $var = do { ... }? Ben Morrow <ben@morrow.me.uk> - 2012-03-02 20:06 +0000
  Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-02 19:18 +0000
    Re: $var = do { ... }? tmcd@panix.com (Tim McDaniel) - 2012-03-02 19:24 +0000
      Re: $var = do { ... }? Ben Morrow <ben@morrow.me.uk> - 2012-03-02 20:10 +0000
        Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-02 20:43 +0000
          Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-02 22:47 +0000
          Re: $var = do { ... }? Martijn Lievaart <m@rtij.nl.invlalid> - 2012-03-03 15:58 +0100
            Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-03 17:11 +0000
              Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-03 17:19 +0000
              Re: $var = do { ... }? Martijn Lievaart <m@rtij.nl.invlalid> - 2012-03-03 23:58 +0100
                Re: $var = do { ... }? Ben Morrow <ben@morrow.me.uk> - 2012-03-04 00:29 +0000
                Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-04 14:44 +0000
                Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-05 20:50 +0000
        Re: $var = do { ... }? "Dr.Ruud" <rvtol+usenet@xs4all.nl> - 2012-03-05 11:35 +0100
          Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-05 15:22 +0000
          Re: $var = do { ... }? Ben Morrow <ben@morrow.me.uk> - 2012-03-05 16:38 +0000
      Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-02 20:44 +0000
  Re: $var = do { ... }? tmcd@panix.com (Tim McDaniel) - 2012-03-15 17:09 +0000
    Re: $var = do { ... }? Ben Morrow <ben@morrow.me.uk> - 2012-03-16 00:18 +0000
      Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-16 14:25 +0000
        Re: $var = do { ... }? tmcd@panix.com (Tim McDaniel) - 2012-03-16 21:01 +0000
          Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-16 21:37 +0000
          Re: $var = do { ... }? Ben Morrow <ben@morrow.me.uk> - 2012-03-16 22:56 +0000
            Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-16 23:54 +0000
            Re: $var = do { ... }? tmcd@panix.com (Tim McDaniel) - 2012-03-17 18:48 +0000
              Re: $var = do { ... }? Ben Morrow <ben@morrow.me.uk> - 2012-03-17 22:53 +0000
              Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-18 15:40 +0000
    Re: $var = do { ... }? "Dr.Ruud" <rvtol+usenet@xs4all.nl> - 2012-03-16 14:08 +0100
      Re: $var = do { ... }? tmcd@panix.com (Tim McDaniel) - 2012-03-16 15:25 +0000
      Re: $var = do { ... }? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-03-16 17:46 +0000

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