我有一个标量$订阅者可能是undef,引用HASH或引用ARRAY.我已经为测试分配了样本值$VAR1,$VAR2和$VAR3.
当它是对ARRAY的引用时,我只对$subscriber感兴趣,其中它包含多个值.在其他情况下,我对打印任何东西都不感兴趣(例如,当$subscriber = $VAR2;
在Perl v5.16.2下,代码似乎运行正常;但是,当我将它移动到运行Perl v5.8.8的目标机器时,我收到编译错误：
% ./test.pl Type of arg 1 to keys must be hash (not private variable) at ./test.pl line 23,near "$subscribers) " Execution of ./test.pl aborted due to compilation errors.
代码如下：
#!/usr/bin/perl -w
use strict;
use warnings;
use Data::Dumper;
my $VAR1 = undef;
my $VAR2 = {'msisdn' => '1234'};
my $VAR3 = [
{'msisdn' => '1111'},{'msisdn' => '2222'},{'msisdn' => '3333'},{'msisdn' => '4444'},{'msisdn' => '5555'}
];
my @childMsisdn = ();
my $subscribers = $VAR3;
if (ref $subscribers eq ref []) { # Exclude $VAR1 && $VAR2 scenarios
foreach my $s (keys $subscribers) {
my $msisdn = $subscribers->[$s]->{"msisdn"};
push (@childMsisdn,$msisdn);
}
}
print "childMsisdn = ". join(",",@childMsisdn) ."\n";
解决方法
更换
foreach my $s (keys $subscribers) {
同
foreach my $s (keys %$subscribers) { # $subscribers is hash ref
要么
foreach my $s (0 .. $#$subscribers) { # $subscribers is array ref
从perldoc起
Starting with Perl 5.14,keys can take a scalar EXPR,which must contain a reference to an unblessed hash or array. The argument will be dereferenced automatically. This aspect of keys is considered highly experimental. The exact behavIoUr may change in a future version of Perl.