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

Sibelius 2020.6 - Music notation solutio...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Bookends 13.4.2 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
OmniGraffle Pro 7.16 - Create diagrams,...
OmniGraffle Pro helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use... Read more
Drive Genius 6.1.0 - $79.00
Drive Genius features a comprehensive Malware Scan. Automate your malware protection. Protect your investment from any threat. The Malware Scan is part of the automated DrivePulse utility. DrivePulse... Read more
Tor Browser 9.5 - Anonymize Web browsing...
The Tor Browser Bundle is an easy-to-use portable package of Tor, Vidalia, Torbutton, and a Firefox fork preconfigured to work together out of the box. It contains a modified copy of Firefox that... Read more
VueScan 9.7.28 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
OmniGraffle 7.16 - Create diagrams, flow...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more
WALTR 2 2.6.26 - $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
Airmail 4.1 - Powerful, minimal email cl...
Airmail is an mail client with fast performance and intuitive interaction. Support for iCloud, MS Exchange, Gmail, Google Apps, IMAP, POP3, Yahoo!, AOL, Outlook.com, Live.com. Airmail was designed... Read more
Iridient Developer 3.3.12 - Powerful ima...
Iridient Developer (was RAW Developer) is a powerful image-conversion application designed specifically for OS X. Iridient Developer gives advanced photographers total control over every aspect of... Read more

Latest Forum Discussions

See All

Willy Jetman: Astromonkey's Revenge...
Barcelona-based developer Last Chicken Games are set to bring their game Willy Jetman: Astromonkey's Revenge to both iOS and Android on 9th July. The Metroidvania is already available on the likes of PS4, Switch and PC but now mobile folk will be... | Read more »
The 5 Best Mobile Real Time Strategy Gam...
Real-time strategy games feel like they’d be a perfect fit for mobile, but they’re trickier to pull off that you might think. The traditional mold of base-building and micro management can work on touch screens, but needs to be carefully honed so... | Read more »
Using your phone in a protest
I can't write about games today. There is a struggle happening in the streets right now and it needs everyone's attention. Here's some good info on how you can use your iOS device safely amidst a protest. | Read more »
Dungonian is a card-based dungeon crawle...
Dungonian is a card-based dungeon crawler from developer SandFish Games that only recently launched as a free-to-play title. It offers an extensive roster of playable heroes to collect and enemies to take down, and it's available right now for iOS... | Read more »
Steam Link Spotlight - Signs of the Sojo...
Steam Link Spotlight is a feature where we look at PC games that play exceptionally well using the Steam Link app. Our last entry was XCOM: Chimera Squad. Read about how it plays using Steam Link's new mouse and keyboard support over here. | Read more »
Steampunk Tower 2, DreamGate's sequ...
Steampunk Tower 2 is a DreamGate's follow up to their previous tower defence game. It's available now for both iOS and Android as a free-to-play title and will see players defending their lone base by kitting it out with a variety of turrets. [... | Read more »
Clash Royale: The Road to Legendary Aren...
Supercell recently celebrated its 10th anniversary and their best title, Clash Royale, is as good as it's ever been. Even for lapsed players, returning to the game is as easy as can be. If you want to join us in picking the game back up, we've put... | Read more »
Pokemon Go Fest 2020 will be a virtual e...
Niantic has announced that Pokemon Go Fest will still take place this year although understandably it won't be a physical event. Instead, it will become a virtual celebration and is set to be held on 25th and 26th July. [Read more] | Read more »
Marvel Future Fight's major May upd...
Marvel Future Fight's latest update has now landed, and it sounds like a big one. The focus this time around is on Marvel's Guardians of the Galaxy, and it introduces all-new characters, quests, and uniforms for players to collect. [Read more] | Read more »
SINoALICE, Yoko Taro and Pokelabo's...
Yoko Taro and developer Pokelabo's SINoALICE has now opened for pre-registration over on the App Store. It's already amassed 1.5 million Android pre-registrations, and it's currently slated to launch on July 1st. [Read more] | Read more »

Price Scanner via MacPrices.net

Apple restocks 27″ iMacs, Certified Refurbish...
Apple has restocked Certified Refurbished 2019 27″ iMacs starting at $1529 and up to $350 off the cost of new models. Apple’s one-year warranty is standard, shipping is free, and each iMac features a... Read more
Apple’s new 2020 13″ 4-Core MacBook Airs on s...
B&H Photo has Apple’s new 2020 13″ 4-Core MacBook Airs on sale today for $100 off Apple’s MSRP, only $1199. Expedited shipping is free to many addresses in the US. The MacBook Airs are the same... Read more
New Verizon promo: $150 off any Apple Watch w...
Verizon is offering $150 off any Apple Watch when purchased alongside an iPhone through June 10, 2020. They’re also offering up to $100 on any Apple Watch trade-in. Here are the details: “Get $150... Read more
Last year’s 13″ 2.4GHz MacBook Pros are avail...
Apple has Certified Refurbished 2019 13″ 2.4GHz/256GB 4-Core Touch Bar MacBook Pros available for $1359, $440 off original MSRP. Apple’s one-year warranty is included, shipping is free, and each... Read more
Apple’s new 2020 13″ MacBook Pros on sale for...
Apple reseller Abt Electronics has new 2020 13″ MacBook Pros on sale today for up to $140 off MSRP, starting at $1208. Shipping is free, and most configurations are in stock today. Note that Abt’s... Read more
Apple CEO Reacts To Nationwide Protests Over...
NEWS: 06.03.20 – With the recent death of a black man in the custody of a white police officer igniting outrage among Americans from all walks of life, which resulted in protests and civil unrest... Read more
At up to $420 off MSRP, these Certified Refur...
Apple has Certified Refurbished 2019 16″ MacBook Pros available for up to $420 off the cost of new models, starting at $2039. Each model features a new outer case, shipping is free, and an Apple 1-... Read more
Apple restocks refurbished 3rd generation 12....
Apple restocked select 3rd generation 12.9″ WiFi iPad Pros starting at only $699 and up to $330 off original MSRP. Each iPad comes with a standard Apple one-year warranty, outer cases are new, and... Read more
These wireless carriers are offering Apple’s...
Looking for a deal on Apple’s new iPhone SE? Apple itself offers the unlocked 64GB iPhone SE for $399 or $16.62/month. If you’re willing to try a new carrier, two of Apple’s wireless carriers are... Read more
Save $80 on the 64GB 10.5″ iPad Air with this...
Apple has 10.5″ 64GB WiFi iPad Airs models available for $80 off MSRP, Certified Refurbished. Each iPad comes with Apple’s standard one-year warranty and includes a new outer case. Shipping is free... Read more

Jobs Board

*Apple* Architect - SAIC (United States)
**Description** We are currently seeking a motivated, career and customer oriented Apple Architect to join our team in Washington, DC to begin an exciting and Read more
*Apple* Support Engineer - SAIC (United Stat...
**Description** We are currently seeking a motivated, career and customer oriented Apple Support Engineer to join our team in Washington, DC to begin an exciting and Read more
Perioperative RN - ( *Apple* Hill Surgical C...
Perioperative RN - ( Apple Hill Surgical Center) Tracking Code 60593 Job Description Monday - Friday - Full Time Days Possible Saturdays General Summary: Under the Read more
Senior Practice Manager - *Apple* Hill Eye...
Senior Practice Manager - Apple Hill Eye Center Tracking Code 61713 Job Description Apple Hill Medical Center General Summary: Under general supervision, manages Read more
*Apple* Mac Desktop Support - Global Dimensi...
…Operate and support an Active Directory (AD) server-client environment for all Apple devices operating on the BUMED network + Leverage necessary industry enterprise Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.