TweetFollow Us on Twitter

January 92 - Dinker: the Dynamic Linker

Dinker: the Dynamic Linker

Kurt Schmucker

Many application domains naturally possess an unbounded set of desired features. A signals processing application, for example, needs an unlimited number of filters. A symbolic math package, an unlimited number of mathematical operators. A graphics package, an unlimited number of sketching tools.

Of course, no real application can present an unlimited number of anything to any given user. However, the market as a whole does appear to want an unlimited number of features. What's a developer to do?

Some developers have met this challenge by building in a capability to extend their applications. Using this feature, end users can configure a graphics package, for example, with a set of sketching tools tailored to their needs, or even modify the set of available sketching tools while the application is running.

This enables users to get the maximum use of limited RAM and disk space. Instead of running in a six megabyte MultiFinder partition, for example, an extensible application, with only the needed tools loaded, could run in, say, four megabytes. In fact, one of the best selling MacApp applications, Adobe PhotoShop, uses an extensibility approach with their plug-ins to add new image manipulation algorithms and data access procedures to the application.

Up until now, MacApp has provided no support to those wanting to add extensibility to an application. To make matters worse, the most natural way to add functionality to a MacApp application-by adding new classes to the running application- was something no one had ever done. Some people even thought this was impossible to do on the Mac.

Dinker, the results of recent work by Apple's Advanced Technology Group, adds exactly this capability to MacApp. This article describes what Dinker does and how you can use it in your application. Other articles planned for later issues of FrameWorks will cover Dinker internals and case studies of adding Dinker-based extensibility to commercial MacApp applications.

Dinker is included on the next Essentials, Tools, and Objects CD (ETO 6) as a currently unsupported MacApp experiment. It will be demonstrated at the Orlando '92 MADA Conference in February.

What is Dinker?

Dinker is a dynamic linking mechanism for the Macintosh OS. It lets you write applications whose functionality can be extended at run-time by the addition of new Object Pascal or C++ classes. In particular, Dinker lets the MacApp programmer add new 'view' or 'VIEW' resources, new view classes, new command classes or any other classes at run-time, and to use instances of these classes just like any other object in the application.

The basic run-time architecture of a Dinker application is shown in Figure 1, and then in greater detail in Figure 2 (next page). Dinker will set up entry and exit points in the base and all extensions, and will ensure that the proper global environment (A5 worlds, resource chains, etc.) is established upon crossing the boundaries between the base and the extensions, or between extensions.

Building an application that can be extended at run time via the Dinker is easy. Tell the Dinker version of MABuild to build the application to make use of Dinker. Such an application is called a "base." Then, use MABuild to build each dynamically linkable extension for the application (called an "extension" or a "component"). The total Dinker package used by a MacApp programmer-Dinker itself, the Dinker-aware modified version of MacApp (either a modified version of MacApp 2.0.1, or a modified version of MacApp 3.0ß3), the Dinker-aware version of MABuild, etc.-will cause the entry and exit points to be constructed for the base and for all extensions, and will resolve, at run-time, the invocations of these references. (See future FrameWorks articles for an explanation of the Dinker's inner details.)

A note on terminology-Dinker is a dynamic linker. It lets you "dink in" a new class into a running application. Among dynamic linkers, Dinker is unique in that it enables the dynamic linking of new classes into an object oriented application, like a MacApp application. For a time, the term "oinking" was used to describe this dynamic linking, but this term has fallen into disfavor with the Dinker implementors. A later, supported version of Dinker may have a slick, marketing-approved, copyright-obtained legal name. We hope that all savvy MacApp developers will continue to call it "Dinker" in perpetuity.

What Does dynamic linking do for users?

MacApp developers are subject to the same pressures as every other developer-users want more and more functionality in applications without the resource requirements increasing.

Extensibility lets you achieve these opposing goals. Users can pick which tools to load in the default case (by, for example, placing these in a distinguished folder), yet still have easy access to the tool needed on special occasions. In this way, Dinker lets users manage the resources needed to run your application much like Fifth Generation System's Suitcase™ II lets the user manage fonts, desk accessories, FKEYs, and sounds.

In addition, for those developers who wish to encourage a third-party market surrounding their applications, Dinker provides a way for other MacApp developers to leverage off of your application by developing extensions for it. These third parties will need the entry and exit vector files the Dinker-modified version of MABuild prepares for the application. These could be part of a developer's kit for your application. Developers of extensions do not need access to the source code of the base.

How is dinker used in an application?

To use Dinker, you willl probably need to change your application's source; most applications aren't currently designed for extensibility. Do you have a fixed number of items in a palette-items that the end user may want to add to, or replace? Do you check, upon resuming after a MultiFinder switch, if the user has added functionality to the application "behind your back?" Probably not. There will be as many ways of designing extensibility into MacApp applications as there are clever MacApp programmers.

Automatic loading of components

One way of adding new functionality to an application is to have the user configure a folder with the desired extensions in it. Dinker supports this approach. (If this sounds vaguely like the System 7 Extensions folder, it is. The Finder Extensions mechanism used in System 7 is a special case of the full Dinker design.) The Dinker version of MacApp provides a number of ways to find out which extensions have been loaded. TApplication (in this modified version of MacApp) maintains a list of the currently loaded extensions, and several utility methods and procedures let you easily query this list.

One interesting technique uses a MacApp method that you probably haven't used before: ForAllSubClassesDo in TObject. I used this technique to add an indeterminate number of dinked-in views to a window. It just happened to be the case that while each of these new subviews was a instance of a different class, all the classes were subclasses of a class unique to my application (TBannerView). The code looks like this:

PROCEDURE TBannerDocument.DoMakeViews(…);  
    VAR theWindow:  TWindow;
        theFirstView:   TBannerView;
        currentLoc:     VPoint;
        aView:          TBannerView;
        PROCEDURE AddAView(theClass: ObjClassID);
            currentLoc.v := currentLoc.v + 135;
            aView := TBannerView(NewObjectByClassID(theClass));
            FailNIL(aView );
            aView.IBannerView(…); { this will add it as subView }
        SetVPt(currentLoc, 0, 0);
        { Prime the pump by setting up the window
            with the first view }
        theWindow := NewTemplateWindow(2222, SELF);
        theFirstView := TBannerView(theWindow.FindSubView('MNBN'));
        { Now add the rest of the views }

You could use the same technique to build a palette (when all the new tools to be configured into the palette are subclasses of something like TAbstractTool), or a hierarchical menu.

Manual loading of components

Another way to add functionality is to let the user load new components at any time the application is running. Dinker also supports this. One way you can use this support is to add the appropriate menu items to your application and to process these in a DoMenuCommand something like this code from the Dinker version of DrawShapes:
PROCEDURE TShapeApplication.DoMenuCommand(
            aCommandNumber: CommandNumber); OVERRIDE;
        anExtensionFile:    TList;
        aDomain:            TDomain;
        r:                  Rect;
        shape:              TShape;
        toolsView:          TToolsPalette;
        toolsMenu:          TToolsMenu;

        PROCEDURE DoToItemInExtensionList(item: TObject);
        aDomain := GetExtension ( TFile (item) );
        IF longint(aDomain) <> 0 THEN BEGIN
            { Define the prototype shape this component }   
            SetRect(r, 9, 49, 31, 71 );                     
            OffSetRect(r, 0, 40 * ( gShapesInPalette ) );
            shape := TShape ( Instantiate( aDomain ) );
            gShapesInPalette := gShapesInPalette + 1;
            shape.IShapeExtension(r, gShapesInPalette );
            gShapesArray[gShapesInPalette] := shape;
    PROCEDURE ForceWindowRedraw ( aWindow: TWindow );

    CASE aCommandNumber OF
                IF ChooseDocument( cGetComponent, anExtensionFile )
                THEN BEGIN
                    anExtensionFile.Each( DoToItemInExtensionList );
                    { Now add the new shape to the palette }
                    toolsMenu := TToolsMenu(gToolsMenu);
                    IF longint(toolsMenu) <> 0 THEN
                    ... { Add to Tear offs, etc. here }
                    ForAllWindowsDo( ForceWindowRedraw );
            INHERITED DoMenuCommand(aCommandNumber);
    END; {Case}

'lView' templates in extensions

Often, TView objects are not allocated explicitly by the programmer, but rather are instantiated indirectly via 'view' resources. Extensions also have their own resource chain (forked off of the top of the base's resource chain). You can put 'view' and 'VIEW' resources in your extension. The Dinker extensions to MacApp include Dinker analogs of the familiar utility routines NewTemplateWindow and DoCreateViews, NewComponentTemplateWindow() and DoCreateDinkedViews(), which you can then use to dink in these views from other extensions. Like the standard NewTemplateWindow , NewComponentTemplateWindow lets you access a view by its resource id. However, NewComponentTemplateWindow also lets you access the new window type by the name of the extension that contains it. We have found this to be a natural way to add new functionality to an application in the case that the "important" portion of the extension was the new views being added. In this application, we made the names of the extensions the same as the names of the view.

What are the Drawbacks of using Dinker?

There is no free lunch, and Dinker, too, has some costs. These costs are not in the area of performance. Using instances of dinked-in classes carries only a tiny performance hit on the application. The gotchas of the current Dinker implementation are as follows.

Launch time

Dinker applications take longer to launch than "normal" applications. Remember that Dinker is a dynamic linker. Thus, it is doing the work of the linker at run-time. The amount of time depends mostly on the Mac model you are executing on (no surprise here) and the version of MacApp you are using (remember that MacApp 3 has about twice the number of classes and methods of MacApp 2, and there is a lot more to link in a MacApp 3 application). The additional amounts of launch time can range from less than two seconds (FX, MacApp 2) to more than 30 seconds (Portable, MacApp 3). I hope that future versions of Dinker will be able to reduce these times, but they will never go to zero.

Extensions are application specific

The Dinker internals that make it the only dynamic linker that enables the addition of new classes at run-time also require that a built extension, ready for dinking, be application specific. In addition, any significant changes to the class structure of the application require that all the application's extensions be rebuilt.

What is "significant?" Addition or removal of classes, addition or removal of methods, addition or removal of any entities that the linker needs to know about (for example, invocation of a new Toolbox routine, or moving something from the private interface to the public interface) are prime examples. "Insignificant," from a Dinker point of view, are changes to the implementations of methods or functions that don't add or remove Toolbox calls.

Debugging support

The ease of debugging a Dinker application depends on whether MacApp is used, and what version of MacApp is used. The best case is MacApp 2.0.1. The two main debugging tools designed for MacApp 2.0.1, the Inspector and the MacApp Debugger, are fully integrated with Dinker. The dinked-in classes and any instances of these classes are viewable from these tools and, in fact, you'll have a hard time distinguishing between an instance of a dynamically linked class and a statically linked class. This was a goal of the Dinker implementation, and we believe it has been met (after a lot of hard work and many late night sessions double checking on this integration).

Unfortunately, the situation is not so rosy with respect to a MacApp 3.0ß3 application, or a non-MacApp application. Yes, you can use Dinker without using MacApp. However, it isn't as easy or as convenient, mostly because we planned the first Dinker release to concentrate on the use of Dinker by a MacApp programmer.

The new MABuild, for example, handles the complexity of building the entry and exit vector segments without any work by the MacApp programmer. There are currently no such automated build facilities for the non-MacApp developer. There isn't much debugging support in either SourceBug or SADE® for dynamically linked extensions. Basically, neither of these tools yet know how to read the multiple SYM files associated with the base and all of its currently dinked in extensions, nor do they know to reassess a class hierarchy that has been modified dynamically by Dinker. However, that doesn't mean these debugging tools are useless with a Dinker application. You can use SourceBug with Dinker applications, but with these limitations:

  • SourceBug is confused by the new Class hierarchy that Dinker creates. So SourceBug's browser displays the source code filenames of the base and of the MacApp library rather than its classes.
  • SourceBug only really knows about the code in your base. You must go into your low level debugger if you want to step into your extension.

I hope that these limitations will be removed in the future.

Finally, a goal of Dinker was to require only minimal-and preferably pro forma-changes to a class to change it from being a statically linked piece of functionality to one that could be dynamically linked into the application. We believe this goal has been met. Thus, one possible debugging strategy is to develop and debug your application as a monolithic, statically linked application, and then when it is "bug free," to peel off various pieces of functionality into dynamically linked extensions. (Okay, okay. We know that this is kind of lame, and that your testing manager just had a heart attack even considering this approach. But it's better than nothing, and this is only the early experimental release.)

Support, in general

The Dinker ETO #6 release is an unsupported, experimental release, but Dinker or other dynamic linking mechanisms may be incorporated into future releases of MacApp, MPW, or other development tools.

While it is implemented according to the same architecture as Finder Extensions, Dinker adds significant new dynamic linking functionality to Finder Extensions and thus an extended period of testing is needed. The Dinker work was done by Apple's Advanced Technology Group and is being shared with third-party developers for experimentation and evaluation. If you find dynamic linking to be a useful feature, then it may be supported and extended in future MacApp and MPW releases. Let us know by sending an AppleLink message to the Dinker Product Manager, Tom Chavez (TOM.CHAVEZ).


How Dinker works, and what it is like to add extensibility to an existing commercial MacApp application, will be covered in detail in future FrameWorks articles.


The Dinker folder on ETO #6 is the result of many months of work by employees from several parts of Apple, as well as some Apple contractors. Jed Harris, then in ATG, now in the Developer Tools group, did the original Dinker design. He and Scott Douglass, now in the System Software group at Apple, implemented the first proof of concept that Dinker would actually work. Frank Kurzawa of Refried Software, and Andrew Donoho of Donoho Design Group did the current Dinker implementation under contract to ATG. Frank also designed and implemented the changes to MacApp 2.0.1 and MacApp 3.0ß3 that make it work with Dinker, and he did many of the Dinker sample programs. Joost Kemink and Kurt Schmucker, both of ATG, were the "typical" Dinker users whose dinking needs drove the design, and who did all the testing of Dinker with MacApp. Kurt Schmucker was the author of two of the Dinker sample programs. Tom Chavez is the Dinker Product Manager and guided the Dinker work onto ETO.


Community Search:
MacTech Search:

Software Updates via MacUpdate

The best GIF making apps
Animated GIFs have exploded in popularity recently which is likely thanks to a combination of Tumblr, our shorter attention spans, and the simple fact they’re a lot of fun. [Read more] | Read more »
The best remote desktop apps for iOS
We've been sifting through the App Store to find the best ways to do computer tasks on a tablet. That gave us a thought - what if we could just do computer tasks from our tablets? Here's a list of the best remote desktop apps to help you use your... | Read more »
Warhammer 40,000: Freeblade guide - How...
Warhammer 40,000: Freebladejust launched in the App Store and it lets you live your childhood dream of blowing up and slashing a bunch of enemies as a massive, hulking Space Marine. It's not easy being a Space Marine though - and particularly if... | Read more »
Gopogo guide - How to bounce like the be...
Nitrome just launched a new game and, as to be expected, it's a lot of addictive fun. It's called Gopogo, and it challenges you to hoparound a bunch of platforms, avoiding enemies and picking up shiny stuff. It's not easy though - just like the... | Read more »
Sago Mini Superhero (Education)
Sago Mini Superhero 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: KAPOW! Jack the rabbit bursts into the sky as the Sago Mini Superhero! Fly with Jack as he lifts impossible weights,... | Read more »
Star Wars: Galaxy of Heroes guide - How...
Star Wars: Galaxy of Heroes is all about collecting heroes, powering them up, and using them together to defeat your foes. It's pretty straightforward stuff for the most part, but increasing your characters' stats can be a bit confusing because it... | Read more »
The best cooking apps (just in time for...
It’s that time of year again, where you’ll be gathering around the dinner table with your family and a huge feast in front of you. [Read more] | Read more »
Square Rave guide - How to grab those te...
Square Rave is an awesome little music-oriented puzzle game that smacks of games like Lumines, but with its own unique sense of gameplay. To help wrap your head around the game, keep the following tips and tricks in mind. [Read more] | Read more »
Snowboard Party 2 (Games)
Snowboard Party 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Crowned the best snowboarding game available on the market, Snowboard Party is back to fulfill all your adrenaline needs in... | Read more »
One Button Travel (Games)
One Button Travel 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: “To cut a long story short, If you like interactive fiction, just go buy this one.” - “Oozes the polish that... | Read more »

Price Scanner via

Holiday weekend Mac sales roundup: B&H Ph...
B&H Photo continues to have all new Macs on sale for up to $500 off MSRP as part of their Black Friday/Holiday weekend sale. Shipping is free, and B&H charges NY tax only: - 15″ 2.2GHz Retina... Read more
iMobie Releases its Ace iOS Cleaner PhoneClea...
iMobie Inc. has announced the new update of PhoneClean 4, its iOS cleaner designed to reclaim wasted space on iPhone/iPad for use and keep the device fast. Alongside, iMobie hosts a 3-day giveaway of... Read more
U.S. Cellular Offering iPad Pro
U.S. Cellular today announced that it is offering the new iPad Pro with Wi-Fi + Cellular, featuring a 12.9-inch Retina display with 5.6 million pixels — the most ever in an iOS device. U.S. Cellular... Read more
Newegg Canada Unveils Black Friday Deals for...
Newegg Canada is offering more than 1,000 deep discounts to Canadian customers this Black Friday, available now through Cyber Monday, with new deals posted throughout the week. “Black Friday is... Read more
Black Friday: Macs on sale for up to $500 off...
BLACK FRIDAY B&H Photo has all new Macs on sale for up to $500 off MSRP as part of their early Black Friday sale including free shipping plus NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $... Read more
Black Friday: Up to $125 off iPad Air 2s at B...
BLACK FRIDAY Walmart has the 16GB iPad Air 2 WiFi on sale for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available): - 16GB iPad Air 2 WiFi: $399, save $... Read more
Black Friday: iPad mini 4s on sale for $100 o...
BLACK FRIDAY Best Buy has iPad mini 4s on sale for $100 off MSRP on their online store for Black Friday. Choose free shipping or free local store pickup (if available): - 16GB iPad mini 4 WiFi: $299.... Read more
Black Friday: Apple Watch for up to $100 off...
BLACK FRIDAY Apple resellers are offering discounts and bundles with the purchase of an Apple Watch this Black Friday. Below is a roundup of the deals being offered by authorized Watch resellers:... Read more
Black Friday: Target offers 6th Generation iP...
BLACK FRIDAY Save $40 to $60 on a 6th generation iPod touch at Target with free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary: -... Read more
Black Friday: Walmart and Target offer iPod n...
BLACK FRIDAY Walmart has the 16GB iPod nano (various colors) on sale for $119.20 on their online store for a limited time. That’s $30 off MSRP. Choose free shipping or free local store pickup (if... Read more

Jobs Board

*Apple* Site Security Manager - Apple (Unite...
# Apple Site Security Manager Job Number: 42975010 Culver City, Califo ia, United States Posted: Oct. 2, 2015 Weekly Hours: 40.00 **Job Summary** The Apple Site Read more
WiSE *Apple* Pay Quality Engineer - Apple (...
# WiSE Apple Pay Quality Engineer Job Number: 44313381 Santa Clara Valley, Califo ia, United States Posted: Nov. 13, 2015 Weekly Hours: 40.00 **Job Summary** Join our Read more
Holiday Retail Associate with *Apple* Knowl...
…and assertive.Someone who can troubleshoot iOS devices (iPhone and iPad) and Apple Mail issues.Someone who can offer solutions.Someone who can work weekends.Someone with Read more
*Apple* Systems Engineer (Mclean, VA and NYC...
Summary:Assist in providing strategic direction and technical leadership within the Apple portfolio, including desktops, laptops, and printing environment. This person Read more
Simply Mac *Apple* Specialist- Service Repa...
Simply Mac is the largest premier retailer of Apple products in the nation. In order to support our growing customer base, we are currently looking for a driven Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.