But mfc appear to encourage the employ of catch-by-pointer;, C/C++ Programming

Assignment Help:

Q: But MFC appear to encourage the employ of catch-by-pointer; should I do the similar?

A: Depends. If you're utilizing MFC and catching one of their exceptions, by all means, do it their way. Similar goes for any framework: while in Rome, do as the Romans. Don't attempt to enforce a framework into your way of thinking, even if "your" way of thinking is "better." If you decide to employ a framework, embrace its way of thinking employ the idioms that its authors expected you to use.

But if you're developing your own framework and/or a piece of the system which does not directly based on MFC, then don't catch by pointer only because MFC does it that way. While you're not in Rome, you don't essentially do as the Romans. In this case, you must not. Libraries such as MFC predated the standardization of exception handling in the C++ language, and some libraries employ a backwards-compatible form of exception handling which requires (or at least encourages) you to catch by pointer.

The difficulty with catching by pointer is that it's not clear who (if anyone) is responsible for deleting the pointed-to object. For instance, consider the following:

MyException x;

void f()                                                                                  

{

MyException y;

try {                                                                                                                                              

switch (rand() % 3) {

case 0: throw new MyException;

case 1: throw &x;

case 2: throw &y;

}

}

catch (MyException* p) {

...  should we delete p here or not???!?

}

}

There are three basic problems here:

 

It might be tough to decide whether to delete p in the catch clause. For instance, if object x is inaccessible to the scope of the catch clause, as while it's buried in the private part of some class or is static in some other compilation unit, it may be tough to figure out what to do.

If you solve out the primary problem by constantly using new in the throw (and thus consistently by delete in the catch), then exceptions always employ the heap that can cause problems while the exception was thrown since the system was running low on memory.

If you solve out the first problem by constantly not using new in the throw (and thus consistently not using delete in the catch), then you probably won't be capable to allocate your exception objects as locals (as then they might get destructed too early), wherein case you'll ought to worry about thread-safety, semaphores, locks etc. (intrinsically static objects are not thread-safe).

It isn't to say it's not possible to work through these issues. The point is this: if you catch by reference instead of by pointer, life is easier. Why make life tough when you don't have to?

The moral: ignore throwing pointer expressions, and ignore catching by pointer, unless you're using an existing library that "wants" you to do so.

 


Related Discussions:- But mfc appear to encourage the employ of catch-by-pointer;

Advanced error checking and structures, It is standard on functions to prov...

It is standard on functions to provide some indication that the function has succeeded in its operation. Consider the Scanf function:     scanf("%d",&number1);   If the functio

Assigment Help, I need help in the C++ programming assignment. I can send t...

I need help in the C++ programming assignment. I can send the files the assignment is times 3hrs.

Program to develope dating service to form couples, In this assignment, you...

In this assignment, you will develop a program named "match" to be used by a dating service to form couples. Given the number of gentlemen, the number of ladies, and a list of acce

C programs, 2. a) Define a structure to store roll no, name and marks of a ...

2. a) Define a structure to store roll no, name and marks of a student. b) Using the structure of Q2. a), above write a ''C'' program to create a file "student.dat". There must be

Write a program that reads a line of characters, Write a program that reads...

Write a program that reads a line of characters from the user and displays that entire line after converting any uppercase characters to lowercase also change any lowercase charact

Write a program to find files-unix, This programming assignment is for use ...

This programming assignment is for use in the LINUX/UNIX environment!! Introduction: System administration often requires custom written programs and tools. One problem a s

Pebble merchant, there is a pebble merchant. he sells the pebbles,that are ...

there is a pebble merchant. he sells the pebbles,that are used for shining the floor.his main duty is to take the length of the room side but he sometines mistakes doing that and m

Decode the code, Smugglers are becoming very smart day by day. Now they hav...

Smugglers are becoming very smart day by day. Now they have developed a new technique of sending their messages from one smuggler to another. In their new technology, they are send

Explain the terms- substitutability and extensibility, Explain the terms- S...

Explain the terms- Substitutability and Extensibility Substitutability - The objects of a properly derived class can be safely and easily substituted for an object of its

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd