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Think about Loose Coupling

Re^2: Spot the bug!

by diotalevi (Canon)
on Oct 26, 2006 at 15:18 UTC ( #580788=note: print w/replies, xml ) Need Help??

in reply to Re: Spot the bug!
in thread Spot the bug!

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; }

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Re^3: Spot the bug!
by tlm (Prior) on Oct 27, 2006 at 00:49 UTC

    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?

    the lowliest monk

      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.

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