使用 Google gflags 簡化命令列參數處理

（本文章僅適用於C++程式）
寫服務程式時，如果需要提供命令列參數。傳統的方法是手工解析argv參數，或者使用getopt函數。兩種方法都比較費勁。使用Google gflags可以大大簡化命令列參數處理。安裝gflag從官方地址http://code.google.com/p/google-gflags/下載gflags並安裝。比如我下載的是1.5版本。

[yichi@yichi tmp]$ wget http://google-gflags.googlecode.com/files/gflags-1.5.tar.gz[yichi@yichi tmp]$ tar zxvf gflags-1.5.tar.gz[yichi@yichi tmp]$ cd gflags[yichi@yichi gflags-1.5]$ ./configure –prefix=$HOME/google-library[yichi@yichi gflags-1.5]$ make j=4 & make install

使用gflags範例程式碼：http://www.faithbee.com/wp-content/uploads/2011/05/gflags-sample.tar.bz2main.cc

// Copyright (c) 2011, D-Media Communication Technology Inc.// All rights reserved.////// ---// Author: Yichi Zhang <zyichi@gmail.com>//// File content description here #include "server.h" #include <google/gflags.h> #include <string> #include <stdio.h> DEFINE_bool(memory_pool, false, "If use memory pool");DEFINE_bool(daemon, true, "If started as daemon");DEFINE_string(module_id, "", "Server module id"); DEFINE_int32(http_port, 80, "HTTP listen port");DEFINE_int32(https_port, 443, "HTTPS listen port"); intmain(int argc, char** argv){  ::google::ParseCommandLineFlags(&argc, &argv, true);   // XXX NOTE: Should add 'FLAGS_' prefix.  printf("Server module id: %s\n", FLAGS_module_id.c_str());   if (FLAGS_daemon) {    printf("Run as daemon: %d\n", FLAGS_daemon);  }  if (FLAGS_memory_pool) {    printf("Use memory pool: %d\n", FLAGS_daemon);  }   Server server;   return 0;}

server.h

// Copyright (c) 2011, D-Media Communication Technology Inc.// All rights reserved.////// ---// Author: Yichi Zhang <zyichi@gmail.com>//// File content description here #include <google/gflags.h> #include <stdio.h> // Declare, defined in 'main.cc'.DECLARE_int32(http_port);DECLARE_int32(https_port); class Server { public:  Server() {    // XXX NOTE: Should add 'FLAGS_' prefix.    printf("HTTP listen port: %d\n", FLAGS_http_port);    printf("HTTPS listen port: %d\n", FLAGS_https_port);  }  virtual ~Server() {}  private:  ;};

　　

  編譯樣本程式

[yichi@yichi gflags-sample]$ g++ -o gflags-sample main.cc -I $HOME/google-library/include -L $HOME/google-library/lib -lgflags

運行樣本程式帶參數運行

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sampleServer module id:Run as daemon: 1HTTP listen port: 80HTTPS listen port: 443

帶參數運行，使用等號賦值

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample -module_id="server_007" -daemon=true -http_port=8080 -https_port=4443Server module id: server_007Run as daemon: 1HTTP listen port: 8080HTTPS listen port: 4443

帶參數運行，使用空格分割參數和值

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample -module_id "server_007" -daemon true -http_port 8080 -https_port 4443Server module id: server_007Run as daemon: 1HTTP listen port: 8080HTTPS listen port: 4443

顯示協助

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample –helpgflags-sample: Warning: SetUsageMessage() never calledFlags from main.cc:-daemon (If started as daemon) type: bool default: true-http_port (HTTP listen port) type: int32 default: 80-https_port (HTTPS listen port) type: int32 default: 443-memory_pool (If use memory pool) type: bool default: false-module_id (Server module id) type: string default: ""

參考資料Google gflags官方文檔：http://google-gflags.googlecode.com/svn/trunk/doc/gflags.html from:http://www.faithbee.com/?p=415