我应该如何将对象传递给子程序？

Question

这些中最好的还是最差的方法之一？

利用范围:

my $cache = CHI->new( driver => 'File', expires_in => 3600 );

sub one {
    if ( my $data = $cache->get( 'key_one' ) ) {
    # ...
}

sub two {
    if ( my $data = $cache->get( 'key_two' ) ) {
    # ...
}

传递对象作为参数:

my $cache = CHI->new( driver => 'File', expires_in => 3600 );

sub one {
    my ( $cache ) = @_;
    if ( my $data = $cache->get( 'key_one' ) ) {
    # ...
}

sub two {
    my ( $argument1, $cache ) = @_;
    if ( my $data = $cache->get( 'key_two' ) ) {
    # ...
}

或在子程序中创建一个新实例:

sub one {
    my $cache = CHI->new( driver => 'File', expires_in => 3600 );
    if ( my $data = $cache->get( 'key_one' ) ) {
    # ...
}

sub two {
    my $cache = CHI->new( driver => 'File', expires_in => 3600 );
    if ( my $data = $cache->get( 'key_two' ) ) {
    # ...
}

Answer 1

第一种选择使用全局变量,而不是那么热.第三种选择是额外的开销.也不是那么好,所以我想中间选择在你的问题的背景下更可取.更广泛的问题是为什么子程序需要知道缓存？看起来他们只担心数据.我会考虑获取数据并将其传递给子例程,如果它被缓存或刚刚创建,他们不必担心.

Answer 2

除非您想要更改原始数据,否则使用方法2通过引用传递参数更安全:

my $cache = CHI->new( driver => 'File', expires_in => 3600 );

one (\$cache);

sub one {
    my ( $cache ) = @_;
    if (any {!defined @_} $cache { //can expand on this
       croak "missing parameters";
    if ( my $data = $cache->get( 'key_one' ) ) {
    # ...
}