Basic HTML version of Foils prepared Sept 20 97

Foil 26 Some Remarks about Subroutines - III

From Perl5 and Advanced Perl4 Features Computational Science for Information Age Course CPS616 -- Sept 20 97. by Geoffrey C. Fox,Nancy McCracken,Tom Scavo


1 Note differences between my() and local()
2 my($x); # declares $x to be private to the block
3 local($x); # declares $x to be known to this block and all routines invoked within the block
4 Typeglob or symbolic reference can be used to pass arguments by reference and not by value
5 This has usual advantage that subroutine alters "global" and not a "local" copy -- especially relevant for complex data structures where you do not want expense of copying
  • Scalars are always passed by reference (not by value); by explicitly changing $_[0..], you can affect global scalars

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