but then what about globals? Should they always be aliased? ... And then what about $_ – do we leave it as a strange exception case?

$_ already is a "strange exception", it gets used without being mentioned and has a myriad of magical behaviours associated with it (that I wouldn't want to loose), this would continue the tradition of that variable.

In the case of other globals, I hadn't really thought about them much as I don't make use of them much, but having thought about it, I don't think that there is a case for localisation.

If they already exist in the symbol table, they have been used before, and should not be localised. The programmer has explicitly indicated that they wish to re-use this variable, and any changes should persist. Trust that the programmer knows what they are doing.

If the programmer wants to both re-use an earlier global, and retain it's original value afterward, he has the option to localise it himself--just as he would have to in any other situation.

If the variable does not yet exist in the symbol table, there is no great value in localising it, and you remove the potential for using it's final value subsequent to the loop.

So basically, $_ is special--because it is already special--and for any other variable, the user controls localisation through the keywords my or local, just as he would for any other construct.

Seems to me that would be the most logical, useful and consistant behaviour. Still, it's all academic anyway.