At_exit handling

ruby-talk
1

Lately I asked on IRC:

- Does at_exit work on a per-class basis? or is it global

The answer was:

- global, and it's equivalent to END{} block AFAIK

I believe this answer is true.

Now my question is ... isn't this a bit of a code smell in that when I
use many many different classes who some of them may use at_exit code,
this leads to a fragile and imperfect design?

Explanation:

I am writing on a pseudo-ruby shell (with a bash-like syntax).

I usually use 'q' to quit it.

Then suddenly one day, I required some files, one of which used at_exit,
and I had a weird bug in that the exiting no longer worked as-is,
instead it raised some SystemExit exception.

This confused me a lot because that should not happen at all ever.

Then I realized that the faulty code part was in at_exit (that ruby file
was doing something odd, probably at_exit was not needed either, but
still)

It kind of taught me to be wary with at_exit.

Am I correct in that at_exit may be potentially harmful in a very large
ruby project, when multiple at_exits are doing different things?

···

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Posted via http://www.ruby-forum.com/.

2

Any and all code is potentially harmful in any size project. I don't see how at_exit is different or special in that aspect in any way.

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On Jan 12, 2012, at 14:44 , Marc Heiler wrote:

Am I correct in that at_exit may be potentially harmful in a very large
ruby project, when multiple at_exits are doing different things?

3

It should happen always, regardless of at_exit:

begin
  exit 1
rescue SystemExit => e
  p e
end

# => #<SystemExit: exit>

···

On Jan 12, 2012, at 14:44 , Marc Heiler wrote:

Then suddenly one day, I required some files, one of which used at_exit,
and I had a weird bug in that the exiting no longer worked as-is,
instead it raised some SystemExit exception.

This confused me a lot because that should not happen at all ever.

4

Marc Heiler wrote in post #1040604:

I am writing on a pseudo-ruby shell (with a bash-like syntax).

I usually use 'q' to quit it.

Then suddenly one day, I required some files, one of which used at_exit,
and I had a weird bug in that the exiting no longer worked as-is,
instead it raised some SystemExit exception.

This confused me a lot because that should not happen at all ever.

If you want your code to terminate without calling any at_exit handlers
you've pulled in,
use "exit!"

Regards,

Brian.

···

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Posted via http://www.ruby-forum.com/\.

5

I wrote a gist not too long ago that seems appropriate here:

···

On Fri, Jan 13, 2012 at 3:09 PM, Ryan Davis <ryand-ruby@zenspider.com> wrote:

On Jan 12, 2012, at 14:44 , Marc Heiler wrote:

Then suddenly one day, I required some files, one of which used at_exit,
and I had a weird bug in that the exiting no longer worked as-is,
instead it raised some SystemExit exception.

This confused me a lot because that should not happen at all ever.

It should happen always, regardless of at_exit:

begin
exit 1
rescue SystemExit => e
p e
end

# => #<SystemExit: exit>