Level of Indirection solves every Problem
What does the quote "Level of Indirection solves every Problem" mean in Computer Science? ...
indirection
Have you come across any reason for three levels of indirection?
Just flicking through one of my favourite books (Ellen Ullman's The Bug) and there is a small bit where one programmer confronts another over three levels of indirection: ***object_array = ***winarray; I get the idea of double indirection - a way of passing a pointer into a function, and allowing it to point to an object created withi...
Include indirection on Visual C++
Let's say we have an application that will need Boost to compile. Boost being an external library, updated regularly, and our application having multiple binaries and multiple versions ("multiple" as in "Let them grow and multiply"... don't ask...), we need an easy to update/maintain indirection to have for each app's version link with t...
How to overload the indirection operator? (C++)
I'm trying to create an iterator class as a member-class for a list class, and am trying to overload the indirection operator (*) to access the list it's pointing to: template<class T> T list<T>::iterator::operator*(iterator& iter) { return ((iter.lstptr)->current)->data; } where lstptr is a pointer to a list, current is a pointer...
C# P/Invoke: How to achieve double indirection for a field of a structured parameter
I am calling into a native dll from C#. For the specific function in question, one of the parameters I need is a structure which contains a doubly-indirect field (pointer to a pointer). For example, take the following C prototype and structs: int someFunc(SomeStruct* result); struct SomeStruct { DWORD foo; AnotherStruct** p...
Accessing variables from a struct
How can we access variables of a structure? I have a struct: typedef struct { unsigned short a; unsigned shout b; } Display; and in my other class I have a method: int NewMethod(Display **display) { Display *disp=new Display(); *display = disp; disp->a=11; } What does **display mean? To access variables of struct I h...
Purpose of dereferencing a pointer as a parameter in C.
I recently came along this line of code: CustomData_em_free_block(&em->vdata, &eve->data); And I thought, isn't: a->b just syntactic sugar for: (*a).b With that in mind, this line could be re-written as: CustomData_em_free_block(&(*em).vdata, &(*eve).data); If that's the case, what is the point of passing in &(*a), as a para...
Direct invocation vs indirect invocation in C
I am new to C and I was reading about how pointers "point" to the address of another variable. So I have tried indirect invocation and direct invocation and received the same results (as any C/C++ developer could have predicted). This is what I did: int cost; int *cost_ptr; int main() { cost_ptr = &cost; //...
TOUGH: Dealing with deeply nested pointers in C++
I define this structure: struct s_molecule { std::string res_name; std::vector<t_particle> my_particles; std::vector<t_bond> my_bonds; std::vector<t_angle> my_angles; std::vector<t_dihedral> my_dihedrals; s_molecule& operator=(const s_molecule &to_assign) { res_name = to_assign.res_name; my_particles = to_assign.m...
Weird Pointer issue in C++
I'm running into a VERY frustrating pointer issue. I previously posted here: http://stackoverflow.com/questions/3114997/tough-dealing-with-deeply-nested-pointers-in-c But that post got overly long and is stale, so I chose to repost with more details. Here is my header file that defines my types: #include <string> #include <vector> #i...
Why is my multi-dimensional dynamic allocation in C not working?
Hi all, I have been trying to figure out the problem with my allocation and use of a multidimensional dynamically allocated array in C. I'd really appreciate any help. I've tried two approaches. The first: cdr = (double ***) malloc(NUM_REGIONS * sizeof(double **)); for(i=0; i<NUM_REGIONS; i++){ cdr[i] = (double **) malloc(numRating...
How to re-attach an object to EclipseLink session after deserialization
Here's a simple POC: public void main(String[] args) { final String FILE_NAME = "c:/poc.ser"; try { HotelJdo hotel = HotelJdoFinder.findById(430); ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(FILE_NAME)); // serialize the object oos.writeObject(hotel); oos.close(); ...
Dynamic constant name in PHP
Hello all I am trying to create a constant name dynamically and then get at the value. define( CONSTANT_1 , "Some value" ) ; // try to use it dynamically ... $constant_number = 1 ; $constant_name = ("CONSTANT_" . $constant_number) ; // try to assign the constant value to a variable... $constant_value = $constant_name; But I find th...