Perl组合技：sub
毋容置疑，编程的分分合合是很重要的思想。就像下面的文件一样：
use File::Spec::Functions;use strict;################################################################# routines for Debug output#sub DEBUG_Activate {open (DEBUG_CHANNEL , ">&STDOUT") or LOG_MsgExit ("Failed to attempt to open STDERR channel") ;}sub DEBUG_Disable{open (DEBUG_CHANNEL , File::Spec->devnull() ) or LOG_MsgExit ("Failed to attempt to open NULL device");}sub DEBUG_Write{print DEBUG_CHANNEL ">>$_\n";}sub DEBUG_Close{close(DEBUG_CHANNEL);}####################################################################################### Routines for dealing with the logfilesub LOG_Disable {open (LOGFILE, ">&STDOUT") or LOG_MsgExit ("Failed to attempt to open STDOUT device");DEBUG_Write ("Log messages output will be redirected to STDOUT");}sub LOG_Create{my $file;$file=$_;open (LOGFILE,">$file") or LOG_MsgExit("Cannot create the logfile $file");close(LOGFILE);DEBUG_Write("Logfile $file has been created"); }##############################33# returns 1 if file is writable, otherwise returns 0# if cannot write, try to create it, and if success, then returns 1#sub LOG_IsLOGFILEWritable{my $file;my $k;$file = $_;if ( -w $file ) {return 1;}else {$k = open(LOGFILE,">>$file");if ($k) { close(LOGFILE); return 1;}else { return 0; }}}########################################################### Activates the channel LOGFILE, so print to this channel# means write in the specified logfilesub LOG_Enable{my $file;$file = $_;utime(time(),time(),$file);open (LOGFILE , ">>$file") or LOG_MsgExit ("Failed to attempt to open the logfile $file");DEBUG_Write ("Opened the logfile: $file");}sub LOG_Close{ close(LOGFILE);}sub LOG_Msg {my $t;$t=localtime();print LOGFILE "$t : $_\n";DEBUG_Write ("Logged this alarm...: $_");}sub LOG_MsgExit{my $t;$t=localtime();print LOGFILE "$t : $_\n";DEBUG_Write("$_");exit;}return 1;
很明显这是一个.pm 的文件， 是.pl的模块，他们的关系就像： .html - - .css ， .pl - - .pm
顿悟了吗
这里有好多的sub 函数，供随时调用（当然这里只举了个关于 logfile 的例子）.
每一个sub函数，就相当于一个基本技，在主函数中进行组合，就是组合技，那么你就可以放肆地连招了。
PS：转载请注明出处，作者No. Liu
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