TweetFollow Us on Twitter

May 93 - Three MacApp 3.0.1 Shortcuts

Three MacApp 3.0.1 Shortcuts

Ken Victor

The following three shortcuts have made my life much simpler while developing a new MacApp 3.0.1 application using C++.

Try and Catch Macros

In a past issue of "Develop" magazine, the C macros for Try and Catch were defined for MacApp 2. I got used to using these when I was developing a MacApp 2 product using C++, and although the MacApp 3 approach to exception handling is easier to use with C++, I wanted to continue to use Try and Catch. I find this more meaningful to read than if fi.Try(). So here is my version for MacApp 3:
#define try                    \
    FailInfo fi;            \
    if (fi.Try()) {
#define catch               \
    fi.Success();           \
    }                       \
    else
#define try2                \
    if (fi.Try()) {
#define success     fi.Success()
#define resignal    fi.ReSignal()

Thus you can write code that looks like the following:

try {
    …
    }
catch {
    …
    resignal;
    }

    or:

try …
catch ;

    or:

try {
    …
    success;
    return;
    …
    }
catch ;

These macros nest properly so that you can write the following:

try {
    …
    try {
        …
        }
    catch {
        …
        resignal;
        }
    …
    }
catch {
    …
    resignal;
    }

The Try2 macro is used if you want a second, or third, Try clause at the same level as a previous one. E.g.:

try {
    …
    }
catch {
    …
    resignal;
    }
…
try2 {
    …
    }
catch {
    …
    resignal;
    }

The Catch macro could easily be modified to automatically resignal, but I felt it best not to hide this, and to save the few bytes in the situation where I didn't need to resignal.

TMyDocument Shortcut

When developing a new application, each time you add, change, or delete a class variable from your TMyDocument class, there are up to 8 different methods that you may have to change:
Initialize
IMyDocument
DoInitialState
Free
FreeData
DoNeedDiskSpace
DoRead
DoWrite

And it is important that DoRead and DoWrite perform operations in the same order. I got tired of trying to remember to update each of these methods, and of having to go back and forth between DoRead and DoWrite to make sure I was doing things in the right order. I therefore decided to localize all these functions into one common method. The price I pay for this is a slight performance hit due to the extra switches in my common routine, a slight violation of clean segmentation, and a violation of the tenant of a single routine performing a single function. I felt that these were a small price to pay for the increased convenience. When my app is complete, I can always do away with this common routine, and place the appropriate code in each of the specific methods.

My common routine is defined as follows:

enum tDocIterType {
    forReading,
    forWriting,
    forSizing,
    forInitialize,
    forIDoc,
    forDoInitial,
    forFreeData,
    forFree
    };
void    DoSRWIIDF(  tDocIterType iterType,
                    TFile* aFile,
                    long& dataForkBytes,
                    long& rsrcForkBytes,
                    Boolean modifier = false);

Each of my standard methods is now quite simple and implemented similarly to the following:

pascal void TMyDocument::DoNeedDiskSpace(
                        TFile* itsFile,
                        long& dataForkBytes,
                        long& rsrcForkBytes) {
    // count us
    DoSRWIIDF(  forSizing,
                itsFile, 
                dataForkBytes, 
                rsrcForkBytes);
    }   //  end of TMyDocument :: DoNeedDiskSpace 

My common routine locks the document, so I can read and write to it comfortably, allocates any needed Streams, and for each member variable in the document performs a switch to perform the required action. The core of the code follows:

#pragma segment DocReadWriteEtc
void TMyDocument::DoSRWIIDF(    tDocIterType iterType,
                    TFile* aFile,
                    long& dataForkBytes,
                    long& rsrcForkBytes,
                    Boolean modifier) {
TStream*        aStream = NULL;
VOLATILE( aStream);

// lock us just in case
    SignedByte myState = LockHandleHigh( (Handle) this);

    try {
    // get stream for i/o
        switch (iterType) {
            case forSizing:
                aStream = new TCountingStream;
                ((TCountingStream*) aStream)->ICountingStream();
                aStream->SetPosition( 0);
                inherited::DoNeedDiskSpace( aFile,
                                        dataForkBytes,
                                        rsrcForkBytes);
                break;
            case forReading:
            case forWriting:
                aStream = new TFileStream;
                ((TFileStream*) aStream)->IFileStream( aFile);
                aStream->SetPosition( 0);
                if (iterType == forReading)
                    inherited::DoRead( aFile, modifier);
                else inherited::DoWrite( aFile, modifier);
                break;
            }
    //  field 1
        switch (iterType) {
            case forSizing:     // fall thru
            case forWriting:
                aStream->WriteBytes( &field1, sizeof( field1));
                break;
            case forReading:    
                aStream->ReadBytes( &field1, sizeof( field1));
                break;
            case forInitialize:
                …
                break;
            case forIDoc:
                …
                break;
            case forDoInitial:
                …
                break;
            case forFreeData:
                …
                break;
            case forFree:
                …
                break;
            }
    //  field 2
        …
    // free stream
        if (iterType == forSizing)
            dataForkBytes += aStream->GetSize();
        FreeIfObject( aStream);
    // unlock us
        HSetState( (Handle) this, myState);
    }
catch {
    // free stream
        FreeIfObject( aStream);
    // unlock us
        HSetState( (Handle) this, myState);
    resignal;
    }
}   //  end of TMyDocument :: DoSRWIIDF

Now whenever I add, change, or delete a field, it is a simple matter of modifying the one "block" of code.

Floating TEditTexts

In several of my dialogs, I had fields in which I wanted to restrict what characters the user could enter. I wanted to beep if the user typed an illegal character. In looking at the MacApp3Tech$ archives, the suggestions for accomplishing this basically involved subclassing TEditText and a few other classes so that you could create you own floating TEView with its appropriate behavior. Nick Nallick, in his article "Text Filtering with Behaviors" in the July 1992 FrameWorks describes such an approach. I decided to try the different approach of attaching a Behavior to the dialog floating TEView, and much to my relief this worked out even better than I thought it would, and is in fact a very general approach. You can even attach multiple instances of this behavior to the floating view, and each instance can act on different characters and/or be applied to different TEditTexts in the dialog.

The Behavior basically looks at each character the user types into a TEditText and beeps if this is an illegal character, or if it is a legal character simply passes it along the behavior chain for normal operation. The behavior will also examine each character in a pasted string and beep if the string contains any illegal characters or pass the string along. Using the behavior is quite simple and relies on the fact that there is only one floating TEView per dialog window and that this view is usually the window's target after the window has been created. First create your window and establish it as a dialog so that the floating TEView will exist. Then create the behavior:

TBhvrInputFilter* aCharBeeper = new TBhvrInputFilter;

Then call the '"I" method, passing the window:

aCharBeeper->IBhvrInputFilter( aWindow);

This will initialize the Behavior and attach it to the floating TEView. It finds the floating TEView by first looking at the window's target to see if is a member of TDialogTEView; if not, it searches the window's sub views until it finds a TDialogTEView to attach to.

Next tell the Behavior which TEditText views you wish to check by passing the identifier(s) of these views:

aCharBeeper->AddView( aEditText->GetIdentifier());
aCharBeeper->AddView( anotherEditText->GetIdentifier());

And lastly, tell the behavior which characters are allowed. The default is to not allow any characters. However there are several methods for specifying the legal characters.

aCharBeeper->AllowNumbers();
aCharBeeper->AllowControlChars();
aCharBeeper->AllowChar( '/');

The above sequence will allow numbers and the slash character, the common characters for a date input view, but will beep on all other characters. It will also allow all control characters so that normal editing can take place.

Advantages

This approach relies on the fact that a common single floating TEView is passed around, rather than each TEditText having its own floating TEView. This leads to both the advantages and disadvantages of this approach, as opposed to subclassing TEditText to install your own floating TEView. This approach is simpler to use and requires less code since there is no need to subclass. The disadvantage is that since this behavior is attached to the only floating TEView, each TEditText that you use uses this behavior, even if you don't want to filter that TEditText. The list of views to filter is maintained as a TLongintList and I haven't noticed any unacceptable performance (but I have not made any measurements). This approach is especially useful if you have several TEditTexts that require the same filtering. And, as mentioned above, if you have different filtering requirements, you can simply install multiple instances of this behavior, each with their own set of views to check, and their own set of legal characters.

Post processing

While further developing my app, I had a need to process TEditText after each character's editing action had taken place, but before any other processing could occur. (What I wanted was to perform name lookup and recognition based on the user's [partial] input string.) Since my use of behaviors for filtering input worked so well, I decided to capitalize on what I already had. I broke up TBhvrInputFilter into two classes: TBhvrFTEVFilter and TBhvrInputFilter. TBhvrFTEVFilter is an abstract class with methods for attaching itself to the floating TEView, and for adding, removing, and checking which sub views to work with. TBhvrInputFilter is now a subclass of TBhvrFTEVFilter and contains the specific methods having to do with filtering characters.

I then subclassed TBhvrFTEVFilter again to create a class that would do post processing of the user's input. This turned out to be a little more difficult than I thought it would be at first, but still simpler than any other way I could think of. The difficulty lay in the fact that when I call inherited::DoKeyEvent or inherited::DoMenuCommand, the TDialogTEView actually created command objects, rather than acting immediately. This was solved by my examining the event queue after calling the inherited method, looking for a TTECommand. If I find one, I remove it from the queue, call its DoIt, Commit, and Free methods. I can then easily get the resulting edited text and act as I wish.

In hindsight, I realized that I may have been able to use MacApp's dependency and notification techniques to accomplish this post processing. However, I now had something that worked, and I believe I might have had problems with characters after the first typed character, and "if it ain't broke..."

 
AAPL
$96.52
Apple Inc.
-0.67
MSFT
$44.60
Microsoft Corpora
-0.28
GOOG
$595.03
Google Inc.
-0.95

MacTech Search:
Community Search:

Software Updates via MacUpdate

Airfoil 4.8.7 - Send audio from any app...
Airfoil allows you to send any audio to AirPort Express units, Apple TVs, and even other Macs and PCs, all in sync! It's your audio - everywhere. With Airfoil you can take audio from any... Read more
Microsoft Remote Desktop 8.0.8 - Connect...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more
xACT 2.30 - Audio compression toolkit. (...
xACT stands for X Aaudio Compression Toolkit, an application that encodes and decodes FLAC, SHN, Monkey’s Audio, TTA, Wavpack, and Apple Lossless files. It also can encode these formats to MP3, AAC... Read more
Firefox 31.0 - Fast, safe Web browser. (...
Firefox for Mac offers a fast, safe Web browsing experience. Browse quickly, securely, and effortlessly. With its industry-leading features, Firefox is the choice of Web development professionals... Read more
Little Snitch 3.3.3 - Alerts you to outg...
Little Snitch gives you control over your private outgoing data. Track background activityAs soon as your computer connects to the Internet, applications often have permission to send any... Read more
Thunderbird 31.0 - Email client from Moz...
As of July 2012, Thunderbird has transitioned to a new governance model, with new features being developed by the broader free software and open source community, and security fixes and improvements... Read more
Together 3.2 - Store and organize all of...
Together helps you organize your Mac, giving you the ability to store, edit and preview your files in a single clean, uncluttered interface. Smart storage. With simple drag-and-drop functionality,... Read more
Cyberduck 4.5 - FTP and SFTP browser. (F...
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more
iExplorer 3.4 - View and transfer all th...
iExplorer is an iPhone browser for Mac lets you view the files on your iOS device. By using a drag and drop interface, you can quickly copy files and folders between your Mac and your iPhone or... Read more
Airmail 1.4 - Powerful, minimal email cl...
Airmail is a powerful, minimal mail client.It was designed to retain the same experience with a single or multiple accounts and provide a quick, modern and easy-to-use user experience. Airmail... Read more

Latest Forum Discussions

See All

Revolution 60 Review
Revolution 60 Review By Jordan Minor on July 24th, 2014 Our Rating: :: LASS EFFECTUniversal App - Designed for iPhone and iPad Revolution 60 is a bold, cinematic action game with ambition to spare.   | Read more »
Matter (Photography)
Matter 1.0.1 Device: iOS Universal Category: Photography Price: $1.99, Version: 1.0.1 (iTunes) Description: Add stunning 3D effects to your photos with real-time shadows and reflections. Export your creations as photos or video loops... | Read more »
Fanatic Earth Review
Fanatic Earth Review By Brittany Vincent on July 24th, 2014 Our Rating: :: BY-THE-NUMBERSUniversal App - Designed for iPhone and iPad Kemco’s stable of mobile RPGs grows, but in Fanatic Earth’s situation it’s a case of quantity... | Read more »
Together for iOS (Productivity)
Together for iOS 1.0 Device: iOS Universal Category: Productivity Price: $9.99, Version: 1.0 (iTunes) Description: Together is an app for keeping things in one place. Notes, documents, images, movies, sounds, web pages and bookmarks... | Read more »
The Phantom PI Mission Apparition (Game...
The Phantom PI Mission Apparition 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: ** Release sale! 50% off for a limited time! ** The Phantom PI Mission Apparition is a spooky, puzzly, rock’... | Read more »
The Great Prank War (Games)
The Great Prank War 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: Help Mordecai, Rigby, Muscle Man and Skips take the park back from Gene and his goons with a plethora of prank-related... | Read more »
Teenage Mutant Ninja Turtles (Games)
Teenage Mutant Ninja Turtles 1.0.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.0 (iTunes) Description: Download the all new Teenage Mutant Ninja Turtles Official Movie Game! | Read more »
Dream Revenant (Games)
Dream Revenant 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: EXCLUSIVE LAUNCH PRICE ! Dream Revenant is at $1.99 for a limited time ! | Read more »
Traps n' Gemstones (Games)
Traps n' Gemstones 1.00 Device: iOS Universal Category: Games Price: $2.99, Version: 1.00 (iTunes) Description: LAUNCH SALE! 40% off, JULY ONLY! TRAPS N' GEMSTONES is an adventurous platform game, among gamers typically known as the... | Read more »
Soccer Physics (Games)
Soccer Physics 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: One-button soccer game! So dumb it's fun. "Soccer Physics is probably the funniest football game you'll play on iOS" —... | Read more »

Price Scanner via MacPrices.net

What Should Apple’s Next MacBook Priority Be;...
Stabley Times’ Phil Moore says that after expanding its iMac lineup with a new low end model, Apple’s next Mac hardware decision will be how it wants to approach expanding its MacBook lineup as well... Read more
ArtRage For iPhone Painting App Free During C...
ArtRage for iPhone is currently being offered for free (regularly $1.99) during Comic-Con San Diego #SDCC, July 24-27, in celebration of the upcoming ArtRage 4.5 and other 64-bit versions of the... Read more
With The Apple/IBM Alliance, Is The iPad Now...
Almost since the iPad was rolled out in 2010, and especially after Apple made a 128 GB storage configuration available in 2012, there’s been debate over whether the iPad is a serious tool for... Read more
MacBook Airs on sale starting at $799, free s...
B&H Photo has the new 2014 MacBook Airs on sale for up to $100 off MSRP for a limited time. Shipping is free, and B&H charges NY sales tax only. They also include free copies of Parallels... Read more
Apple 27″ Thunderbolt Display (refurbished) a...
The Apple Store has Apple Certified Refurbished 27″ Thunderbolt Displays available for $799 including free shipping. That’s $200 off the cost of new models. Read more
WaterField Designs Unveils Cycling Ride Pouch...
High end computer case and bag maker WaterField Designs of San Francisco now enters the cycling market with the introduction of the Cycling Ride Pouch – an upscale toolkit with a scratch-free iPhone... Read more
Kingston Digital Ships Large Capacity Near 1T...
Kingston Digital, Inc., the Flash memory affiliate of Kingston Technology Company, Inc.,has announced its latest addition to the SSDNow V300 series, the V310. The Kingston SSDNow V310 solid-state... Read more
Apple’s Fiscal Third Quarter Results; Record...
Apple has announced financial results for its fiscal 2014 third quarter ended June 28, 2014, racking up quarterly revenue of $37.4 billion and quarterly net profit of $7.7 billion, or $1.28 per... Read more
15-inch 2.0GHz MacBook Pro Retina on sale for...
B&H Photo has the 15″ 2.0GHz Retina MacBook Pro on sale for $1829 including free shipping plus NY sales tax only. Their price is $170 off MSRP. B&H will also include free copies of Parallels... Read more
Apple restocks refurbished Mac minis for up t...
The Apple Store has restocked Apple Certified Refurbished Mac minis for up to $150 off the cost of new models. Apple’s one-year warranty is included with each mini, and shipping is free: - 2.5GHz Mac... Read more

Jobs Board

Sr Software Lead Engineer, *Apple* Online S...
Sr Software Lead Engineer, Apple Online Store Publishing Systems Keywords: Company: Apple Job Code: E3PCAK8MgYYkw Location (City or ZIP): Santa Clara Status: Full Read more
Senior Interaction Designer, *Apple* Online...
**Job Summary** Apple is looking for a hands on Senior…will be a key player in designing for the Apple Online Store. The ideal designer will have a Read more
*Apple* Sales Chat Rep - Apple (United State...
…is looking for motivated, outgoing, and tech savvy individuals who want to offer Apple Customers an unparalleled customer experience over chat. At Apple , we believe Read more
Mac Expert - *Apple* Online Store Mexico -...
…MUST be fluent in English and Spanish to be considered for this position At Apple , we believe that hard work, a fun environment, creativity and innovation fuel the Read more
*Apple* Industrial Design CAD Sculptor - App...
**Job Summary** The Apple Industrial Design team is looking for a CAD sculptor/Digital 3D modeler to create high quality CAD models used in the industrial design process Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.