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
$111.78
Apple Inc.
-0.87
MSFT
$47.66
Microsoft Corpora
+0.14
GOOG
$516.35
Google Inc.
+5.25

MacTech Search:
Community Search:

Software Updates via MacUpdate

Monolingual 1.6.2 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
NetShade 6.1 - Browse privately using an...
NetShade is an Internet security tool that conceals your IP address on the web. NetShade routes your Web connection through either a public anonymous proxy server, or one of NetShade's own dedicated... Read more
calibre 2.13 - Complete e-library manage...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital librarian... Read more
Mellel 3.3.7 - Powerful word processor w...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
ScreenFlow 5.0.1 - Create screen recordi...
Save 10% with the exclusive MacUpdate coupon code: AFMacUpdate10 Buy now! ScreenFlow is powerful, easy-to-use screencasting software for the Mac. With ScreenFlow you can record the contents of your... Read more
Simon 4.0 - Monitor changes and crashes...
Simon monitors websites and alerts you of crashes and changes. Select pages to monitor, choose your alert options, and customize your settings. Simon does the rest. Keep a watchful eye on your... Read more
BBEdit 11.0.2 - Powerful text and HTML e...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more
ExpanDrive 4.2.1 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Adobe After Effects CC 2014 13.2 - Creat...
After Effects CC 2014 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous After Effects customer). After Effects CS6 is still available... Read more
Evernote 6.0.5 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more

Latest Forum Discussions

See All

Make your own Tribez Figures (and More)...
Make your own Tribez Figures (and More) with Toyze Posted by Jessica Fisher on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
So Many Holiday iOS Sales Oh My Goodness...
The holiday season is in full-swing, which means a whole lot of iOS apps and games are going on sale. A bunch already have, in fact. Naturally this means we’re putting together a hand-picked list of the best discounts and sales we can find in order... | Read more »
It’s Bird vs. Bird in the New PvP Mode f...
It’s Bird vs. Bird in the New PvP Mode for Angry Birds Epic Posted by Jessica Fisher on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Telltale Games and Mojang Announce Minec...
Telltale Games and Mojang Announce Minecraft: Story Mode – A Telltale Games Series Posted by Jessica Fisher on December 19th, 2014 [ permalink ] | Read more »
WarChest and Splash Damage Annouce Their...
WarChest and Splash Damage Annouce Their New Game: Tempo Posted by Jessica Fisher on December 19th, 2014 [ permalink ] WarChest Ltd and Splash Damage Ltd are teaming up again to work | Read more »
BulkyPix Celebrates its 6th Anniversary...
BulkyPix Celebrates its 6th Anniversary with a Bunch of Free Games Posted by Jessica Fisher on December 19th, 2014 [ permalink ] BulkyPix has | Read more »
Indulge in Japanese cuisine in Cooking F...
Indulge in Japanese cuisine in Cooking Fever’s new sushi-themed update Posted by Simon Reed on December 19th, 2014 [ permalink ] Lithuanian developer Nordcurrent has yet again updated its restaurant simulat | Read more »
Badland Daydream Level Pack Arrives to C...
Badland Daydream Level Pack Arrives to Celebrate 20 Million Downloads Posted by Ellis Spice on December 19th, 2014 [ permalink ] | Read more »
Far Cry 4, Assassin’s Creed Unity, Desti...
Far Cry 4, Assassin’s Creed Unity, Destiny, and Beyond – AppSpy Takes a Look at AAA Companion Apps Posted by Rob Rich on December 19th, 2014 [ permalink ] These day | Read more »
A Bunch of Halfbrick Games Are Going Fre...
A Bunch of Halfbrick Games Are Going Free for the Holidays Posted by Ellis Spice on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »

Price Scanner via MacPrices.net

The Apple Store offering free next-day shippi...
The Apple Store is now offering free next-day shipping on all in stock items if ordered before 12/23/14 at 10:00am PT. Local store pickup is also available within an hour of ordering for any in stock... Read more
It’s 1992 Again At Sony Pictures, Except For...
Techcrunch’s John Biggs interviewed a Sony Pictures Entertainment (SPE) employee, who quite understandably wished to remain anonymous, regarding post-hack conditions in SPE’s L.A office, explaining “... Read more
Holiday sales this weekend: MacBook Pros for...
 B&H Photo has new MacBook Pros on sale for up to $300 off MSRP as part of their Holiday pricing. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1699... Read more
Holiday sales this weekend: MacBook Airs for...
B&H Photo has 2014 MacBook Airs on sale for up to $120 off MSRP, for a limited time, for the Thanksgiving/Christmas Holiday shopping season. Shipping is free, and B&H charges NY sales tax... Read more
Holiday sales this weekend: iMacs for up to $...
B&H Photo has 21″ and 27″ iMacs on sale for up to $200 off MSRP including free shipping plus NY sales tax only. B&H will also include a free copy of Parallels Desktop software: - 21″ 1.4GHz... Read more
Holiday sales this weekend: Mac minis availab...
B&H Photo has new 2014 Mac minis on sale for up to $80 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 1.4GHz Mac mini: $459 $40 off MSRP - 2.6GHz Mac mini: $629 $70 off MSRP... Read more
Holiday sales this weekend: Mac Pros for up t...
B&H Photo has Mac Pros on sale for up to $500 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2599, $400 off MSRP - 3.5GHz 6-core Mac Pro: $3499, $... Read more
Save up to $400 on MacBooks with Apple Certif...
The Apple Store has Apple Certified Refurbished 2014 MacBook Pros and MacBook Airs available for up to $400 off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Save up to $300 on Macs, $30 on iPads with Ap...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
iOS and Android OS Targeted by Man-in-the-Mid...
Cloud services security provider Akamai Technologies, Inc. has released, through the company’s Prolexic Security Engineering & Research Team (PLXsert), a new cybersecurity threat advisory. The... Read more

Jobs Board

*Apple* Store Leader Program (US) - Apple, I...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on experience, Read more
Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.