It doesn't perform a regular expression match, for one.

So now you are demonising regular expressions? Should we scrap regexes all together?

If you've never changed the text of an exception message and then had to change the regex of handlers, good. I have.

And you've never had to restructure your exceptions? I have.

I say again, how is that different?

Look at all the places in the Exception Class example I posted where the (same) name of the exception (class) is embedded inside a string.

• Think about how many opportunities that creates for typos.

  Typos that are not even subjected to the rigours of syntax checking.

  By moving your error texts into the name-space hierarchy, you've just moved the problem elsewhere and wrapped it up in a heap of complexity.

  You've re-created the very problems that Abigail attempted to address with Inside Out objects. That of preventing strict from working by putting program "keywords" into hash keys. Stashes are just hashes.

  And along the way, thrown away a bunch of useful tools. Like regex.

  Which means you can no longer follow Postel's Prescription: "Be generous in what you accept, rigorous in what you emit", because (for example) you cannot use a regex with /i to ignore casing.

  Or just $@ =~ /^Uninitialised variable/ to match just the invariant part of the error.

• And all the places in that example that need to be changed when you inevitably have to re-structure your exception handling.

  You've just quadrupled the number of places in the code you need to change. And in the process added 3 more layers; 5 more dependencies; and a crap load more code into the bargain.

  There is an undeniable truth that says: more code == more bugs. And you've just added a bunch more complicated code trying to avoid a situation that can be trivially dealt with without it.

Maybe those can be avoided by using Exception::Class better? If so, please enlighten us with an example.