新手提问：tie的问题

laoxia

1. use NDBM_File;
   
2. tie %ALIASES, "NDBM_File", "/etc/aliases", 1, 0
   
3.     or die "Can't open aliases: $!\n";
   
4. while (($key,$val) = each %ALIASES) {
   
5.     print $key, ' = ', $val, "\n";
   
6. }
   
7. untie %ALIASES;

复制代码

tie %ALIASES, "NDBM_File", "/etc/aliases", 1, 0

1，0 是什么意思？说是什么LIST？

先谢

apile

tie %ALIASES, "NDBM_File", "/etc/aliases", 1, 0
    or die "Can't open aliases: $!\n";

"/etc/aliases", 1, 0
給%ALIASES初值的..
相關欄位定義..你得去看看NDBM_File.pm
TIEHASH method裡面的東西...
tie是個蠻複雜的觀念...主要用來將一個複雜的結構..
透過array、var、hash代替整個package...
要支援tie必須該package有下列method才能tie正常...

支援VAR TIE:
TIESCALAR
FETCH
STORE
DESTROY

支援ARRAY TIE:
TIEARRAY
FETCH
STORE
DESTROY

支援HASH TIE:
TIEHASH
FETCH
STORE
DELETE
EXISTS
FIRSTKEY
CLEAR
DESTROY

laoxia

谢apile