perl - 为什么第 4 章中来自 'Learning Perl 6th edition' 的示例无法运行？

Question

我被困在学习 Perl 第 6 版的第 4 章练习 4 第 78 页。我从第 301 页复制了问题的代码示例。我在 Ubuntu 11.04 上使用 Perl 版本 5.10.1。我遇到了无法弄清楚的错误，有人可以帮忙吗？我将在下面列出代码和错误消息。

#!/usr/bin/perl -w
use strict;

greet( 'Fred' );
greet( 'Barney' );

sub greet {
  state $last_person;

  my $name = shift;

  print "Hi $name! ";

  if( defined $last_person ) {
      print "$last_person is also here!\n";
 }
  else {
      print "You are the first one here!\n";
}
  $last_person = $name;
}


Global symbol "$last_person" requires explicit package name at ./ex4-4 line 8.
Global symbol "$last_person" requires explicit package name at ./ex4-4 line 14.
Global symbol "$last_person" requires explicit package name at ./ex4-4 line 15.
Global symbol "$last_person" requires explicit package name at ./ex4-4 line 20.
Execution of ./ex4-4 aborted due to compilation errors.

Answer 1

你需要说use feature 'state'在脚本顶部启用 state变量。见 perldoc -f state .