NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c++-part1/3742

Internet Message Format | 1996-08-06 | 1.4 KB

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From: John Leonard <[e-mail]>
Newsgroups: comp.lang.c++
Subject: Constructors and exceptions
Date: Thu, 25 Jan 1996 10:58:17 -0500
Organization: 12th of Nov, Inc
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Let's say that you have a class, we'll call it WindowClass, which, when it is constructed,
opens a file, allocates memory for the file, reads the file into memory, and then opens a window.
Let's say furthermore that you are going to create the object with a call to 'new' like this:

     WindowClass     *aWC = new WindowClass(filename);

     Now let's say that during initialization of the object, after it allocates the memory it finds
that it cannot open the window. At this point I suppose it would be necessary to de-allocate the
memory that had been allocated and close the file, then throw an exception. Now as far as I can tell
when you use 'new' like this to allocate and initialize an object two things must happen:
first, space must be reserved by the 'new' function for the objects data members, then, the
constructor is called. If this process aborts after the memory has been allocated how can the
application free it?
     Thanks,
     John Leonard