Thanks. How did I miss that sentence in the man pages?
:-)
sgurukrupagmailcom
Last Activity: Apr 27 '12, 03:15 PM
Joined: Apr 26 '08
Location: Bangalore, India
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Is the 'read' unix system call interface goofed up?
Hi,
The prototype for the 'read' system call as given in the POSIX standard reads like this:
This system call returns the number of bytes read from the file associated with the file descriptor 'filedes'.Code:#include <unistd.h> ssize_t read(int filedes, void* buf, size_t nbytes);
The odd thing about it is that we need to specify the number of bytes to be... -
Hmmm... I need some time to work on what Savage, Banfa and weaknessforcats have suggested.. I think I need to understand the different aspects of class inheritance as remarked by weaknessforcats .
Can you suggest a good book or article that would explain all the intricacies of class inheritance and template design ? I have Bjarne Stroustrup's "C++ Programming Language - 3rd edition". But it's quite terse and needs to be read...Leave a comment:
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Banfa suggested moving the enum out of struct, that is surely a solution. But when I have a number of classes like 'struct x', each one having its own 'enum OPTIONS', then I would end up with a corresponding number of enums. I would, then, have to devise names for each of the enums. Also the relationship between the enum and its corresponding class wouldn't be evident. There is one more severe restriction of having many enums like this in the same...Leave a comment:
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Hi,
I am sorry, the last error reported by the GNU compiler is due to a missing semicolon on the line:
Code:enum OPTIONS { YES, NO }Leave a comment:
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cyclic dependency in template instantiation
Hi,
When searching for a solution to my problem I stumbled upon 'Curiously Recurring Template Pattern' see link.
This is how the pattern looks:
But my problem is that I want to access a member of the derived class in the instance of the base class:Code:template < typename T > struct y { } ; struct x : public y < x > { } ;
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Hi,
The singleton design pattern was an interesting article on controlling the number of instances that a user of the class can create.
The warning that RRick gave near the beginning of the thread about throwing exception as pointer to an object is something that we need to heed. It's better to drop the idea of throwing pointer to objects, otherwise it would lead to increased complexity in maintaining the code.
...Leave a comment:
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Hi RRick,
You got to the root of my problem. I am being too obsessive about not allowing others to create instances of my exception class. It's not going to hurt anyone, if they do. However on the positive side my quest did spark off an instructive discussion at the comp.lang.c++ group. click here to see.
This thread does answer the questions raised here. Rick, I have got a few more things to say about handling exceptions in C++...Leave a comment:
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The actual problem that I am trying to solve
Hi,
Well, the reason I am trying to solve this weird problem is because of the following design that I want to implement.
I have an 'exception' class that no other function must be able to throw except a select group of functions. I want the compiler to prohibit people who use my code the capability of throwing instances of my exception class. However they will...Leave a comment:
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Hi,
Sorry folks. I hadn't actually tried compiling the above code with the change included. The change that we thought would work was: throwing a pointer to 'struct m' rather than throwing an instance of 'struct m' itself. To be more clear what I am trying to say is that the code below
...Code:struct m { void n ( ) throw ( m * ) ; int val ; } ; int main ( ) { return 0 ;Last edited by sgurukrupagmailcom; May 4 '09, 03:58 AM. Reason: I wrongly referred to 'g++' as 'gcc'Leave a comment:
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Hi weaknessforcats ,
Thanks for your kind reply. I knew that there should be a simple workaround for this design problem. The solution that you suggested is very simple, I just throw a pointer to the struct instead of the actual object.
Warm Regards,
GauraLeave a comment:
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Cyclic dependency in throw declaration
Hi,
I am unable to get the following to compile
I am using g++ ( GNU version of c++ compiler ) to compile. It throws the following error:Code:struct m { void n ( ) throw ( m ) ; } ; int main ( ) { }
Code:m.cpp:3: error: invalid use of incomplete type 'struct m' m.cpp:2: error: forward declaration of 'struct m'
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Thank you, for your kind reply.
Warm Regards,
GaneshLeave a comment:
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Using variables inside for loop
Hi,
I haven't come accross an elegant solution to a design problem that I show below. Have a look at the piece of code here:
...Code:class Exc { Exc () { System.out.println ("Haribol"); } static public void main ( final String [] args ) { for ( int i = 0 ; i < 4 ; ++ i ) { Exc e = new Exc (); } } }
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