我经常看到GObject库与类似 COM-Windows 的解决方案相比，一般来说，我并没有真正理解这个框架应该解决什么样的问题，以及采用它们带来的好处是什么。
我找到了一些小答案，比如“它是一个可以轻松地将 C 库移植到其他语言的包装器”，但是 GObject 还提供了其他功能，比如信号/插槽机制，还有其他一些事情，但我并没有真正了解大局对这个。
你能用简单的古英语解释一下吗？
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1 回答
5
COM 和类似的库提供了创建和使用二进制面向对象组件的能力。
“二进制”意味着它完全独立于语言，可以在例如 C、C++、Pascal 等中访问。
COM 之上称为“自动化”的层为专门支持“自动化”的组件提供脚本语言的访问。
作为一个具体的例子，Windows API 提供了一个自动化 COM 组件，它代表（并且可以创建或修改）一个 Windows 快捷方式。Windows 快捷方式是“.lnk”文件，有点像符号链接，只是它们必须由应用程序显式取消引用。在我正在写这篇文章的计算机上，MingW g++ 安装包含一个 JavaScript 程序，以使基于 COM 的功能可以作为简单的命令行命令使用。
该程序中的 COM 对象创建：
var Shortcut = WinShell.CreateShortcut( prefix + assigned[lnkname] );
另一个 Windows API COM 对象在哪里，WinShell它是通过脚本宿主环境提供的函数创建的。
完整的程序：
> MinGW\libexec\mingw-get\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 */
于 2013-04-03T11:00:15.093 回答