[PLUG] Working with learning Perl by Randal Schwartz...

[Felix Lee]

"Michael C. Robinson" <michael at goose.robinson-west.com>:
> In the examples for a simple client and server what do the
> lines "my $client = shift;" do?

at compile-time
  declare $client as a lexically local variable
at run-time
  assign to $client the value returned by the builtin operator 'shift'
    which returns the first element of @_
    and removes it from @_

@_ is the array of arguments passed to the function,
  which are passed by value
and @_ is a dynamically local variable
so modifying @_ like that will not change anything in the caller
except
  if the caller uses a "& foo" style function call without ()
  then the callee gets the same @_ as the caller,
  so modifying @_ also modifies the caller's @_

'shift' will use @ARGV instead of @_
  if it's used lexically outside a function or format
  or within an 'eval $string' statement
    (but not an 'eval {block}' statement)
  or within the special forms BEGIN, INIT, CHECK, END.
--