TweetFollow Us on Twitter

Apr 96 Top 10
Volume Number:12
Issue Number:4
Column Tag:Symantec Top 10

Symantec Top 10

By Andy McFarland, Symantec Technical Support

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

Q: I have written a constructor for my CPanorama derived class so I can pass some specific initial values, but now all the parts of the object I specified in the Visual Architect are coming up NULL or garbage. What’s going on?

A: When it comes time to instantiate a class created in Visual Architect, a TCL macro new_by_name is used. It calls a (default) constructor if you have written one, or simply an implied (default-default) constructor if you have not. In either case, the information you specified in the VA is read in from the resource file with GetFrom() after all the constructors in the inheritance chain for your class have been called.

VA can call only default constructors. This includes constructors with no parameters and those for which all the parameters have default values. If you write a constructor that requires that at least one value be passed, you will be creating an object separate from the one VA is going to create. You may still initialize non-TCL members which may have been added to your VA-generated class either in the body of a default constructor or as parameters with default values.

Override GetFrom() if you need to use information from the VA resource file in your intitialization. For instance, a Rect frameRect might be used to save you from having to use the LongToQDRect() macro in toolbox calls that require a Rect. It is perfectly valid (and may be simpler) to put all of your construction/initialization code into GetFrom(), and not write a constructor at all.

Q: VA conveniently creates Save and SaveAs file menu items. What do I actually have to do to save my document to a file?

A: CDocument has a data member itsFile, a CFile*, which will point to whatever species of CFile you actually create, such as CDatafile, CResFile or CPictFile, etc.

The Save As menu item is connected to CDocument:: DoSaveFileAs(). PickFileName() is called from there, which puts up a StandardPutFile() dialog to retrieve the vitals of the file-to-be in an SFReply record.

Finally, DoSaveFileAs() passes the SFReply record to DoSaveAs(), which is what you need to overide in your document class, i.e. in CMain. At this point you need to allocate space for itsFile if you haven’t already.

Now just use all the nifty methods inherited from CFile, CDataFile and perhaps CPictFile to do things like creating, opening, closing, reading and writing to the file and changing its name. For simple file I/O, you may never have to call a File Manager routine directly.

Q: I’m trying to use the TCL macro new_by_name() with a VA-generated class, but it’s not working. What’s up?

A: At the beginning of the file you will see TCL_DEFINE_CLASS_M1(Cfoo,x_Cbar). This is the macro that makes the class an RTTI class (type “Run-Time Type Identification” into THINK Reference for a full explanation.) VA defaults to the M1 suffix, which must be changed to D1 if new_by_name() is to be used. Note that most people will rarely, if ever, need to use new_by_name() instead of TCL_NEW().

Q: Is it possible to create and use a routine descriptor for a member function? When I do so, the arguments are assigned in the wrong order.

A: No. There are various problems involved. There are some implied parameters to member functions, like the this pointer (a pointer to the object). Further, the parameters are passed in a different order (Pascal style) but stack cleanup is done C-style.

Q: I’m getting error -1708, “Couldn’t complete the last command because the AppleEvent was not handled”, when trying to build a library.

A: This usually results from the ToolServer not being installed properly. Check to be sure there is an alias for ToolServer in the (Tools) folder. Also, be sure to rename the alias as “ToolServer”. You may also need to copy the Toolserver folder from the CD, Apple Software:Tools: Toolserver1.1.1, to your hard drive.

Q: How do I get the Standard Console to accept single keystrokes without a Carriage Return?

A: Use the csetmode() function.


#include <stdlib.h> // For Constant EXIT_SUCCESS

#include <iostream.h> // For C++ I/O, cin and cout

//#include <stdio.h> // If you use straight C I/O

#include <console.h> // For cgetmode

main()

{

char c;

printf( "Type a character: ");

csetmode(C_CBREAK,stdin); // Allow single key inputs

c = getchar();

printf( "\nYou typed: '%c'", c, "\n" );

return 0;

}


Q: When I bring my SPM project up to date, a Build Errors window shows up but is empty. What’s going on?

A: Your code is probably generating compiler warnings that you aren’t seeing because the Build Errors window is set to hide them. Click on the Show Warnings button.

Q: Can I use exception handling without the TCL?

A: To use exception handling without the Think Class Library, you must include BRLib and Exceptions.cp in your project. Also, you must compile with the directive:


#define NO_TCL


The four macros used to make exception handling work correctly are:


AUTO_DESTRUCT_OBJECT

TCL_NEW

TCL_END_CONSTRUCTOR

TCL_START_DESTRUCTOR


The macro AUTO_DESTRUCT_OBJECT will guarantee that the destructor is called for an automatic object on the stack. A destructor will work only on a completely constructed object. TCL_END_CONSTRUCTOR helps the compiler to determine the complete construction of an object.

See the example below to see how the macros are used.


class funClass TCL_AUTO_DESTRUCT_OBJECT //macro in class header

{

public:

funClass() { // no arg constructor

cout << "In constructor." << endl;

char * myStr = new char[64]; // allocate memory

TCL_END_CONSTRUCTOR // End of the constructor

}

virtual ~funClass() { // virtual destructor

TCL_START_DESTRUCTOR // Beginning of the destructor

cout << "In destructor." < <endl;

delete [] myStr; // deallocate memory

}

};


Q: Okay. I’ve done everything I’m supposed to do to use exception handling without the TCL, but I get a bunch of link errors when I try to use TCL_NEW.

A: Rebuild BR_Lib.o with

 
  #define TCL_UNSAFE_ALLOCATION.

Q: Why does writing a text handle using CSaver cause garbage in the stream when I read it in?

A: When you create an arbitrary length handle and then fill only part of it, the whole handle length is written (and then read) and so you end up with garbage. To get CSaver to work correctly with handles, you need either to create a handle the right size to begin with, or to resize it when assigning the text to it. As an example we will stream out a CEditText object.

Within the myContents.cp file:

    

// Don’t bother allocating space for the handle.


In GetFrom(), stream in the text:


stream >> myMainText;


In PutTo(), stream out the handle and kill it:


stream << myMainText;

DisposHandle(myMainText);


In CMain.cp::WindowToContents, construct the handle, and fill it:


long len = fMain_Pano3->GetLength(); // get the length we want

itsContents->myMainText = NewHandleCanFail( len );

BlockMove( *fMain_Pano3->GetTextHandle(),

itsContents->myMainText, len );


Special thanks to Michael Hopkins, Craig Conner, Glenn Austin, Scott Morison, and Mark Baldwin.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

VirtualBox 5.1.14 - x86 virtualization s...
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers... Read more
FileZilla 3.24.0 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.24.0: New The context menu for remote file search... Read more
BusyContacts 1.1.6 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
BusyCal 3.1.4 - Powerful calendar app wi...
BusyCal is an award-winning desktop calendar that combines personal productivity features for individuals with powerful calendar sharing capabilities for families and workgroups. Its unique features... Read more
Duplicate Annihilator 5.8.3 - Find and d...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator detects... Read more
MarsEdit 3.7.10 - Quick and convenient b...
MarsEdit is a blog editor for OS X that makes editing your blog like writing email, with spell-checking, drafts, multiple windows, and even AppleScript support. It works with with most blog services... Read more
WALTR 2 2.0.9 - $39.95
WALTR 2 helps you wirelessly drag-and-drop any music, ringtones, videos, PDF, and ePub files onto your iPhone, iPad, or iPod without iTunes. It is the second major version of Softorino's critically-... Read more
Paperless 2.3.9 - $49.95
Paperless is a digital documents manager. Remember when everyone talked about how we would soon be a paperless society? Now it seems like we use paper more than ever. Let's face it - we need and we... Read more
Adobe After Effects CC 2017 14.1 - Creat...
After Effects CC 2017 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). The new, more connected After Effects CC... Read more
Adobe Premiere Pro CC 2017 11.0.2 - Digi...
Premiere Pro CC 2017 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Premiere Pro customer). Adobe Premiere Pro CC 2017 lets you edit... Read more

Super Mario Run dashes onto Android in M...
Super Mario Run was one of the biggest mobile launches in 2016 before it was met with a lukewarm response by many. While the game itself plays a treat, it's pretty hard to swallow the steep price for the full game. With that said, Android users... | Read more »
WarFriends Beginner's Guide: How to...
Chillingo's new game, WarFriends, is finally available world wide, and so far it's a refreshing change from common mobile game trends. The game's a mix of tower defense, third person shooter, and collectible card game. There's a lot to unpack here... | Read more »
Super Gridland (Entertainment)
Super Gridland 1.0 Device: iOS Universal Category: Entertainment Price: $1.99, Version: 1.0 (iTunes) Description: Match. Build. Survive. "exquisitely tuned" - Rock Paper Shotgun No in-app purches, and no ads! | Read more »
Red's Kingdom (Games)
Red's Kingdom 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Mad King Mac has kidnapped your father and stolen your golden nut! Solve puzzles and battle goons as you explore and battle your... | Read more »
Turbo League Guide: How to tame the cont...
| Read more »
Fire Emblem: Heroes coming to Google Pla...
Nintendo gave us our first look at Fire Emblem: Heroes, the upcoming mobile Fire Emblem game the company hinted at last year. Revealed at the Fire Emblem Direct event held today, the game will condense the series' tactical RPG combat into bite-... | Read more »
ReSlice (Music)
ReSlice 1.0 Device: iOS Universal Category: Music Price: $9.99, Version: 1.0 (iTunes) Description: Audio Slice Machine Slice your audio samples with ReSlice and create flexible musical atoms which can be triggered by MIDI notes or... | Read more »
Stickman Surfer rides in with the tide t...
Stickson is back and this time he's taken up yet another extreme sport - surfing. Stickman Surfer is out this Thursday on both iOS and Android, so if you've been following the other Stickman adventures, you might be interested in picking this one... | Read more »
Z-Exemplar (Games)
Z-Exemplar 1.4 Device: iOS Universal Category: Games Price: $3.99, Version: 1.4 (iTunes) Description: | Read more »
5 dastardly difficult roguelikes like th...
Edmund McMillen's popular roguelike creation The Binding of Isaac: Rebirth has finally crawled onto mobile devices. It's a grotesque dual-stick shooter that tosses you into an endless, procedurally generated basement as you, the pitiable Isaac,... | Read more »

Price Scanner via MacPrices.net

Week’s Best Deal: New 2016 13-inch 2.0GHz Mac...
Amazon has the new 2016 13″ 2.0GHz non-Touch Bar MacBook Pros on sale for a limited time for $225 off MSRP including free shipping: - 13″ 2.0GHz MacBook Pro, Space Gray (MLL42LL/A): $1274.99 $225 off... Read more
Back in stock: Apple refurbished Mac minis fr...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $80 off MSRP - 2.6GHz Mac... Read more
Apple Ranked ‘Most Intimate Brand’
The top ranked ‘”intimate” brands continued to outperform the S&P and Fortune 500 indices in revenue and profit over the past 10 years, according to MBLM’s Brand Intimacy 2017 Report, the largest... Read more
B-Eng introduces SSD Health Check for Mac OS
Fehraltorf, Switzerland based independant Swiss company- B-Eng has announced the release and immediate availability of SSD Health Check 1.0, the company’s new hard drive utility for Mac OS X. As the... Read more
Apple’s Education discount saves up to $300 o...
Purchase a new Mac or iPad using Apple’s Education Store 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
4-core 3.7GHz Mac Pro on sale for $2290, save...
Guitar Center has the 3.7GHz 4-core Mac Pro (MD253LL/A) on sale for $2289.97 including free shipping or free local store pickup (if available). Their price is a $710 savings over standard MSRP for... Read more
128GB Apple iPad Air 2, refurbished, availabl...
Apple has Certified Refurbished 128GB iPad Air 2s WiFis available for $419 including free shipping. That’s an $80 savings over standard MSRP for this model. A standard Apple one-year warranty is... Read more
13-inch 2.7GHz Retina MacBook Pro on sale for...
B&H Photo has the 2015 13″ 2.7GHz/128GB Retina Apple MacBook Pro on sale for $100 off MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro (MF839LL/A): $... Read more
Laptop Market – Flight To Quality? – The ‘Boo...
Preliminary quarterly PC shipments data released by Gartner Inc. last week reveal an interesting disparity between sales performance of major name PC vendors as opposed to that of less well-known... Read more
IBM and Bell Transform Canadian Enterprise Mo...
IBM and Bell Canada have announced they are joining forces to offer IBM MobileFirst for iOS market-ready enterprise applications for iPad, iPhone or Apple Watch. Bell, Canada’s largest communications... Read more

Jobs Board

*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Manhattan, NY Introduction: We have immediate job openings for several Desktop Support Technicians with one of our most Read more
Senior Workstation Administrator - *Apple*...
…with extraordinary HR. QualificationsJOB SUMMARY/OVERVIEWThe Senior Workstation Administrator - Apple supports the mission of TriNet by providing advanced level Read more
Intermediate *Apple* macOS Systems Integrat...
**Position Summary:** SC3 is actively seeking an Intermediate Apple macOS systems integration administrator that will be responsible for providing Apple Mac Read more
*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Los Angeles, CA Introduction: We have immediate job openings for several Desktop Support Technicians with one of our Read more
*Apple* Retail - Multiple Positions - Apple,...
SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.