「類COM」框架解決了哪些問題？

Question

與COM-Windows類似的解決方案相比，我經常看到GObject庫。一般來說，我並不真正瞭解這個框架應該解決什麼樣的問題，以及它們的採用會帶來哪些好處。我發現像「它是一個包裝，可以輕鬆地將C庫移植到其他語言」，但GObject還提供其他功能，如信號/插槽機制，還有其他一些事情涉及，但我並不老實瞭解這個大局。

你能用普通的老英語解釋嗎？

Answer 1

COM和類似的庫提供了創建和使用二進制面向對象的組件組件的能力。

「二進制」表示它是相當獨立於語言的， C，C++，Pascal等。

COM上名爲「自動化」的層提供了對腳本語言的訪問，以支持專門支持「自動化」的組件。

---

作爲具體的例子，在Windows API提供代表（並可以創建或修改）Windows快捷方式的自動化COM組件。 Windows快捷鍵是「.lnk」文件，它們有點像符號鏈接，除了它們必須由應用程序明確解除引用。在我寫這篇文章的計算機上，MingW g ++安裝包含一個JavaScript程序，可以將該基於COM的功能作爲簡單的命令行命令提供。

的COM對象創建在該程序：

var Shortcut = WinShell.CreateShortcut(prefix + assigned[lnkname]); 

其中WinShell是另一個Windows API COM對象，通過由腳本主機環境提供的功能創建的。

完整的程序：

> MinGW的\的libexec \ MinGW的，得到\ shlink.js

/* 
* shlink.js 
* 
* $Id: shlink.js,v 1.1 2012/04/06 22:49:36 keithmarshall Exp $ 
* 
* Invoke the Windows Scripting Host to create or modify a windows shortcut, 
* with specified parameters. 
* 
* Usage: 
* cscript -nologo shlink.js [--option[=value] ...] target name 
* 
* Options: 
* --verbose report shortcut parameter assignments on stdout 
* 
* --all-users 
*   create the shortcut in the start menu, or on the 
*   desktop available to all users; (has no effect, 
*   unless --start-menu or --desktop is specified) 
* 
* --desktop create the shortcut on the desktop of the current 
*   user, (or for all users, with --all-users) 
* 
* --start-menu 
*   create the shortcut in the user's start menu, (or 
*   all users' start menu, with --all-users) 
* 
* --arguments="argument list ..." 
*  specify arguments to be passed to the command 
*  invoked by the shortcut 
* 
* --description="text ..." 
*  specify the "tool tip" for the shortcut 
* 
* --hotkey="[SHIFT+][CTRL+][ALT+]key" 
*   specify a hot-key combination which may be used 
*   to invoke the shortcut command 
* 
* --icon="d:\path\to\icon\file[,index]" 
*   specify an icon to associate with the shortcut; 
*   if unspecified, the first icon in the target file, 
*   or failing that, a system default is used 
* 
* --show=normal|maximised|minimised 
*   specify the style of window in which the program 
*   invoked by the shortcut will start running 
* 
* --workingdir="d:\path\to\working\directory" 
*   specify the absolute path name for the directory 
*   which will become the current working directory when 
*   the program invoked by the shortcut is started 
* 
* Parameters: 
* target the path name to the program to invoke, or the file 
*  to be opened, when the shortcut is activated. 
* 
* name the path name for the shortcut file itself; if this 
*  does not end with either a ".lnk" or ".url" extension, 
*  then ".lnk" will be appended, so creating a regular 
*  file system link type shortcut. 
* 
* 
* This file is a component of mingw-get. 
* 
* Written by Keith Marshall <keithmarshall@users.sourceforge.net> 
* Copyright (C) 2012, MinGW Project 
* 
* 
* Permission is hereby granted, free of charge, to any person obtaining a 
* copy of this software and associated documentation files (the "Software"), 
* to deal in the Software without restriction, including without limitation 
* the rights to use, copy, modify, merge, publish, distribute, sublicense, 
* and/or sell copies of the Software, and to permit persons to whom the 
* Software is furnished to do so, subject to the following conditions: 
* 
* The above copyright notice and this permission notice shall be included 
* in all copies or substantial portions of the Software. 
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
* DEALINGS IN THE SOFTWARE. 
* 
*/ 
var cmdName = WScript.ScriptName; 
var WinShell = WScript.CreateObject("WScript.Shell"); 

/* Properties for the shortcut may be specified as arguments 
* to command line options, each of which is represented in the 
* GNU long option form, by keywords with property associations 
* as specified by: 
*/ 
var options = Array(
     "name",  /* File name/path of .lnk file */ 
     "all-users", 
     "start-menu", 
     "desktop", 
     "verbose", 
    /* 
    * Option   Property 
    * -------------  ------------------------- 
    */ 
     "arguments", /* Shortcut.Arguments  */ 
     "description", /* Shortcut.Description */ 
     "hotkey",  /* Shortcut.HotKey  */ 
     "icon",  /* Shortcut.IconLocation */ 
     "show",  /* Shortcut.WindowStyle */ 
     "target",  /* Shortcut.TargetPath  */ 
     "workingdir" /* Shortcut.WorkingDirectory */ 
    ); 

/* The "complain" function provides a mechanism for writing 
* diagnostic messages to stderr, and optionally aborting the 
* calling script. 
*/ 
function complain(condition, message) 
{ 
    WScript.StdErr.WriteLine(cmdName + ": " + message); 
    if(condition < 0) 
    WScript.Quit(-condition); 
    return condition; 
} 

/* Strip ".js" suffix from command name. 
*/ 
var i = cmdName.lastIndexOf(".js"); 
if((i > 0) && (cmdName.substr(i) == ".js")) 
    cmdName = cmdName.substr(0, i); 

/* Initialise all options to "unassigned" state. 
*/ 
var target = -1; 
var lnkname = -1; 
var desktop = -1; 
var allusers = -1; 
var startmenu = -1; 
var verbosity = -1; 
var unassigned = "+++unassigned+++"; 
var assigned = Array(options.length); 
for(var k = 0; k < assigned.length; k++) 
{ 
    switch(options[k]) 
    { 
    case "name": 
     lnkname = k; 
     break; 

    case "desktop": 
     desktop = k; 
     break; 

    case "start-menu": 
     startmenu = k; 
     break; 

    case "all-users": 
     allusers = k; 
     break; 

    case "target": 
     target = k; 
     break; 

    case "verbose": 
     verbosity = k; 
    } 
    assigned[k] = unassigned; 
} 

/* Define the prefix, which will qualify the location 
* of the shortcut; initialise it to nothing, so that by 
* default shortcuts will be located by absolute path name, 
* as specified, or relative to current working directory. 
*/ 
var prefix = ""; 

var j; 
function assign_option(name, value) 
{ 
    switch(name) 
    { 
    case "desktop": 
    case "start-menu": 
    case "all-users": 
    case "verbose": 
     j = i; 
     return "set"; 
    } 
    return value; 
} 

/* Parse the command line. 
*/ 
var argv = WScript.Arguments; 
for(i = 0; i < argv.length; i++) 
{ 
    if(argv(i).indexOf("--") == 0) 
    { 
    /* Handle arguments specifying options... 
    */ 
    if((optind = argv(j = i).indexOf("=") + 1) > 3) 
    { 
     optnam = argv(j).substr(2, optind - 3); 
     optarg = argv(j).substr(optind); 
    } 
    else 
    { 
     optnam = argv(j).substr(2); 
     if(++j < argv.length) 
    optarg = argv(j); 
     else 
    optarg = unassigned; 
    } 

    var matched = 0; 
    for(var k = 0; k < options.length; k++) 
    { 
     if(optnam == options[k]) 
     { 
    matched = 1; 
    assigned[k] = assign_option(options[k], optarg); 
    k = options.length; 
     } 
     else if(options[k].indexOf(optnam) == 0) 
     { 
    if(++matched > 1) 
     complain(-2, cmdName + "option '" + argv(i) + "' is ambiguous"); 
    assigned[k] = assign_option(options[k], optarg); 
     } 
    } 
    if(matched == 1) 
    { 
     i = j; 
    } 
    else 
     complain(-2, "option '" + argv(i) + "' is not supported"); 
    } 

    /* Handle non-option arguments... 
    */ 
    else if((target >= 0) && (assigned[target] == unassigned)) 
    /* 
    * ...the first of which is the target to which the 
    * (shortcut) link is to refer... 
    */ 
    assigned[target] = argv(i); 

    else if((lnkname >= 0) && (assigned[lnkname] == unassigned)) 
    /* 
    * ...the second is the file system path name at which 
    * the link file itself is to be saved... 
    */ 
    assigned[lnkname] = argv(i); 

    else 
    /* ...and any more than two is an error. 
    */ 
    complain(-2, "too many arguments"); 
} 

/* Verify that mandatory arguments have been specified... 
*/ 
if(assigned[target] == unassigned) 
    /* 
    * First of these, the TargetPath specification, is required; 
    * diagnose and abort, if missing. 
    */ 
    complain(-2, "missing argument: no target path specified"); 

if(assigned[lnkname] == unassigned) 
    /* 
    * Second, the path name for the link file itself is essential; 
    * again, diagnose and abort if missing. 
    */ 
    complain(-2, "missing argument: no shortcut name specified"); 

/* We have both the mandatory arguments; check that the link name 
* is properly terminated by a ".lnk" or ".url" suffix... 
*/ 
var suffix = ""; 
if((i = assigned[lnkname].length - 4) > 0) 
    suffix = assigned[lnkname].substr(i); 

/* ...and append ".lnk" as default, if not already present. 
*/ 
if((suffix != ".lnk") && (suffix != ".url")) 
    assigned[lnkname] += ".lnk"; 

/* Add the appropriate prefix for '--desktop' or '--start-menu' shortcuts. 
*/ 
if(assigned[desktop] != unassigned) 
{ 
    if(assigned[startmenu] != unassigned) 
    complain(-2, "options '--desktop' and '--start-menu' are incompatible"); 
    else prefix = WinShell.SpecialFolders((assigned[allusers] == unassigned) 
     ? "Desktop" : "AllUsersDesktop") + "\\"; 
} 
else if(assigned[startmenu] != unassigned) 
    prefix = WinShell.SpecialFolders((assigned[allusers] == unassigned) 
     ? "StartMenu" : "AllUsersStartMenu") + "\\"; 

else if(assigned[allusers] != unassigned) 
    complain(-2, 
     "option '--all-users' also requires '--desktop' or '--start-menu'" 
    ); 

/* Handle verbosity... 
*/ 
function verbose_assignment(property, value) 
{ 
    if(assigned[verbosity] == "set") 
    WScript.Echo(cmdName + ": set " + property + " = " + value); 
} 

/* Initialise the shortcut entity reference. 
*/ 
if(assigned[verbosity] == "set") 
    WScript.Echo(cmdName + ": create shortcut: " + prefix + assigned[lnkname]); 

var Shortcut = WinShell.CreateShortcut(prefix + assigned[lnkname]); 

for(var k = 0; k < options.length; k++) 
{ 
    if(assigned[k] != unassigned) 
    switch(options[k]) 
    { 
     case "arguments": 
    verbose_assignment("Shortcut.Arguments", assigned[k]); 
    Shortcut.Arguments = assigned[k]; 
    break; 

     case "description": 
    verbose_assignment("Shortcut.Description", assigned[k]); 
    Shortcut.Description = assigned[k]; 
    break; 

     case "hotkey": 
    verbose_assignment("Shortcut.HotKey", assigned[k]); 
    Shortcut.HotKey = assigned[k]; 
    break; 

     case "icon": 
    verbose_assignment("Shortcut.IconLocation", assigned[k]); 
    Shortcut.IconLocation = assigned[k]; 
    break; 

     case "show": 
    verbose_assignment("Shortcut.WindowStyle", assigned[k]); 
     var style = Array(
     "normal",  1, 
     "maximised", 3, 
     "maximized", 3, 
     "minimised", 7, 
     "minimized", 7 
    ); 
    for(j = 0; j < style.length; j++) 
     if(style[j++].indexOf(assigned[k]) == 0) 
     { 
     Shortcut.WindowStyle = style[j]; 
     j = 100; 
     } 
    if(j < 100) 
     complain(1, "unrecognised mode '--show=" + assigned[k] + "' ignored"); 
    break; 

     case "target": 
    verbose_assignment("Shortcut.TargetPath", assigned[k]); 
    Shortcut.TargetPath = assigned[k]; 
    break; 

     case "workingdir": 
    verbose_assignment("Shortcut.WorkingDirectory", assigned[k]); 
    Shortcut.WorkingDirectory = assigned[k]; 
    } 
    else if(assigned[verbosity] == "set") 
    WScript.Echo(cmdName + ": option '--" + options[k] + "' is unassigned"); 
} 

/* Commit the shortcut entity to disk. 
*/ 
Shortcut.Save(); 

/* $RCSfile: shlink.js,v $: end of file */