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.

 
AAPL
$102.13
Apple Inc.
+1.24
MSFT
$44.87
Microsoft Corpora
-0.14
GOOG
$571.00
Google Inc.
-6.86

MacTech Search:
Community Search:

Software Updates via MacUpdate

Viber 4.2.2 - Send messages and make cal...
Viber lets you send free messages and make free calls to other Viber users, on any device and network, in any country! Viber syncs your contacts, messages and call history with your mobile device,... Read more
Cocktail 7.6 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
LaunchBar 6.1 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
BBEdit 10.5.12 - Powerful text and HTML...
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
Microsoft Office 2011 14.4.4 - Popular p...
Microsoft Office 2011 helps you create professional documents and presentations. And since Office for Mac 2011 is compatible with Office for Windows, you can work on documents with virtually anyone... Read more
TextWrangler 4.5.10 - Free general purpo...
TextWrangler is the powerful general purpose text editor, and Unix and server administrator's tool. Oh, and also, like the best things in life, it's free. TextWrangler is the "little brother" to... Read more
BitTorrent Sync 1.4.72 - Sync files secu...
BitTorrent Sync allows you to sync unlimited files between your own devices, or share a folder with friends and family to automatically sync anything. File transfers are encrypted. Your information... Read more
Cyberduck 4.5.2 - FTP and SFTP browser....
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
Tinderbox 6.0.3 - Store and organize you...
Tinderbox is a personal content management assistant. It stores your notes, ideas, and plans. It can help you organize and understand them. And Tinderbox helps you share ideas through Web journals... Read more

Latest Forum Discussions

See All

Almightree: The Last Dreamer (Games)
Almightree: The Last Dreamer 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: The world is shattering and you are the only hope to restore the balance. A thrilling and challenging 3D puzzle... | Read more »
Mobile Convolution (Music)
Mobile Convolution 1.0.0 Device: iOS Universal Category: Music Price: $9.99, Version: 1.0.0 (iTunes) Description: | Read more »
Invaders! From Outer Space Review
Invaders! From Outer Space Review By Rob Thomas on August 27th, 2014 Our Rating: :: RETRO NOSTALGIAUniversal App - Designed for iPhone and iPad It’s a shame that Invaders! doesn’t offer deeper gameplay, as this retro-inspired... | Read more »
Spooklands Review
Spooklands Review By Jennifer Allen on August 27th, 2014 Our Rating: :: ONE-TOUCH SHOOTERUniversal App - Designed for iPhone and iPad One-touch simultaneously controls your direction and your weapon in this unique arena shooter.   | Read more »
Heroes of Order & Chaos Add Twitch I...
Heroes of Order & Chaos Add Twitch Integration, New Heroes, and More Posted by Ellis Spice on August 27th, 2014 [ permalink ] | Read more »
Foodie Yama Review
Foodie Yama Review By Jennifer Allen on August 27th, 2014 Our Rating: :: BRIEFLY HOOKSUniversal App - Designed for iPhone and iPad Foodie Yama will draw you in for a brief while, and you’ll never be entirely sure why.   | Read more »
Spotify Connect Turns One, Now Supports...
Spotify Connect Turns One, Now Supports New Devices Posted by Ellis Spice on August 27th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
The Rise of PicsaStock and How You Can M...
We all take plenty of photos, right? That’s the joy of having a reasonably powerful camera in your pocket, thanks to your trusty iPhone and a bevy of similarly useful apps. Wouldn’t it be great to make some money out of those snaps? While your... | Read more »
Appointment With F.E.A.R Review
Appointment With F.E.A.R Review By Jennifer Allen on August 27th, 2014 Our Rating: :: CAMP DELIGHTUniversal App - Designed for iPhone and iPad Ever wanted to be a superhero? Appointment With F.E.A.R is a fine way to live that dream... | Read more »
Indie MOBA ÆRENA’s 2.0 Summer Update Bri...
Indie MOBA ÆRENA’s 2.0 Summer Update Brings New Missions, Skins, and a Champion Posted by Jessica Fisher on August 27th, 2014 [ permalink | Read more »

Price Scanner via MacPrices.net

12-Inch MacBook Air Coming in 4Q14 or 2015 –...
Digitimes’ Aaron Lee and Joseph Tsai report that according to Taiwan-based upstream supply chain insiders, Apple plans to launch a thinner MacBook model either at year end 2014 or in 2015, and that... Read more
Sapphire Screen “Most Wanted” iPhone 6 New Fe...
According to the ‘uSell.com iPhone Most Wanted Survey’ — a representative survey of 1,000 U.S. smartphone users conducted by used iPhone marketplace uSell.com — close to half of all smartphone users... Read more
The iPad’s Real Competitive Challenger (Not S...
It’s been my contention for some time that the iPad is suffering from something of an identity crisis, and I suspect that may be a factor in slackening sales this year. Apple can’t seem to decide... Read more
13-inch 2.6GHz/256GB Retina MacBook Pro on sa...
B&H Photo has the 13″ 2.6GHz/256GB Retina MacBook Pro on sale for $1379 including free shipping plus NY sales tax only. Their price is $120 off MSRP. Read more
Life Inventory iOS Apps – Learn to Know Thyse...
James Hollender’s Life Inventory apps s are now on sale with 20% off thru Labor Day, 09/01/2014. This is a great opportunity to get started on that Moral Inventory you’ve been putting off doing for... Read more
Pocket Watch, LLC. Reveals Cloud Server For P...
Beaumont, Texas based Pocket Watch, LLC. has announced the availability of its new ActivePrint Cloud Server Powered by Raspberry Pi. With this small standalone box almost any USB printer or available... Read more
902it Simplifies Area Code Changes For Nova S...
The east coast Canadian provinces of Nova Scotia and Prince Edward Island are phasing in 10 digit telephone dialing, to be fully in place by November, in order to accommodate a second area code to... Read more
Boomerang iPad Stand Mounts Your iPad Anywher...
Boomerang, a Mountable Stand with Multiple Viewing Angles, is now available for iPad Air. Boomerang combines several functions that aim to expand your iPad’s potential in one, elegant product. The... Read more
Retina MacBook Pros available starting at $10...
The Apple Store has Apple Certified Refurbished 13″ and 15″ MacBook Pros available starting at $929. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz MacBook Pros (4GB RAM/... Read more
Apple 27-inch Thunderbolt Display (refurbishe...
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

Jobs Board

*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
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
Position Opening at *Apple* - Apple (United...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.