package MyTest;

my $lexvar = 7;

# This function is called automatically whenever
# anyone 'use's (or 'require's, I'm pretty sure)
# our module.  Note that this happens at COMPILE TIME.
sub import {
  # symbol table manipulation usually requires
  # the use of symbolic references...
  no strict 'refs';

  # Figure out where to export to.
  # Check `perldoc -f caller` for info on caller.
  my $pkg_to_export_to = (caller)[0];

  # Make the scalar part of the entry in the symbol
  # table of the calling package for 'lexvar' into a hard
  # reference to our lexical variable.  This is called
  # typeglob aliasing.
  *{$pkg_to_export_to . '::lexvar'} = \$lexvar;
}