Re^2: Spot the bug!

[diotalevi]

Localizing $@ would have protected your caller against your clobbering $@. You'd still have the alias/copy bug so now shift() would always return undef because $@ now is always blank but at least you'd be safer. When using $@, always, always, always copy it out first. The smallest piece of code can go clobber $@ so you should always copy it out before examining it.

sub foo {
    local $@;
    return eval { bar( shift ) } || 0;
}

[tlm]

Agreed. But what about just using @_ = @_ instead of local @_? Assignment to @_ is what the docs prescribe for breaking the aliasing. Any reason for preferring one approach over the other?

[diotalevi]

I said local $@, not @_. There's no point to localizing @_, that's your input! You'd copy stuff out of it if you needed that behavior.