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Re^4: Is this a bug in Perl scope?

by tobyink (Abbot)
on Jul 22, 2012 at 19:15 UTC ( #983079=note: print w/replies, xml ) Need Help??

in reply to Re^3: Is this a bug in Perl scope?
in thread Is this a bug in Perl scope?

This syntax:

package foo { ... }

... only works in Perl 5.14 and above. In earlier versions of Perl, you'll need a semicolon before the block...

package foo; { ... }

Though it is in my experience more conventional to put the package declaration inside the block itself:

{ package foo; ... }

Update: as per AnomalousMonk's post below, this latter style has the added advantage that the package declaration itself is lexically scoped, so after perl parses the closing curly brace it puts you back into the main package. I knew that already really. ;-) The new Perl 5.14 syntax also does this, but the middle example does not.

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

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Re^5: Is this a bug in Perl scope?
by AnomalousMonk (Chancellor) on Jul 22, 2012 at 22:59 UTC
    { package foo; ... }

    In addition, prior to 5.14 (and even post-5.14) this idiom terminated the scope of the enclosed package, which was (and is) very useful.

    >perl -wMstrict -le "{ package Foo; sub my_pkg { print 'works pre-5.14: ', __PACKAGE__; } } ;; package Bar { sub my_pkg { print 'post-5.14: ', __PACKAGE__; } } Foo::my_pkg(); Bar::my_pkg(); print __PACKAGE__; " works pre-5.14: Foo post-5.14: Bar main

    Update: Expanded code example.

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