CDT/Better Debugging (GSoC project)

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This page contains detailed description of "Better Debugging Environment" project for Google Summer of Code.

TODO: add screenshots.

TODO: re-read.



The goal of this project is to create more user-friendly C/C++ debugging environment. By finishing this project there will be:

  • More powerful "Watch expressions" window, which will have default formatters for STL containers (map, vector, queue, priority_queue, ...) and custom user types.
  • Support for custom user formatters.
  • Ability to inspect variables by simply hovering mouse over them in the code editor. This feature will be ported from old CDI-GDB to new DFS-GDF preserving same functionality.

Detailed Project Description

This projects is intended to make debugging with CDT at least as comfortable as with Microsoft Visual Studio.

Custom and Default formatters

One of main parts of this project is to provide users with more readable representation of their data. Formatter is a function that accepts object and returns its human-readable description.

For example, when user watches on a vector<int> variable he/she expects to see its content, not details of internal implementation:

vector<int> v;
for (int i = 0; i < 5; i++)

should display value of v as {0, 1, 2, 3, 4}.

Successful completion of this project will implement at least following default formatters for standard STL containers:

  • vector, set, multiset and list will display all items formatted in following way: {item1, item2, ... , itemN}.
  • stack will display all items formatted in following way: (item1, item2, ... , itemN], where item1 is stack top and itemN is stack bottom.
  • queue and deque will display all items formatted in following way: (item1, item2, ... , itemN), where item1 is front of the queue and itemN is back of the queue.
  • priority_queue will display all items formatted in following way: (top:item1 other: {item2, ... , itemN}), where item1 is top of the queue and items 2..N are remaining queued items.
  • map, multimap as {key1->value1, key2->value2, ... , keyN->valueN}.
  • bitset 's like (0111 1110 10)

Of course, all formatters will be applied recursively, thus:

vector<int> row1, row2;
vector< vector<int> > matrix;

will display matrix as {{1, 2}, {3, 4}}.

Secondly, all standard C/C++ constructions will also have default formatters:

T* obj;

can displayed as "ptr_to: <value of *obj>", or as "null_ptr" if obj is null.

void* obj;

can be displayed as: ptr_to: <addr>

Displaying array of objects should also be intuitive. If arr is defined as int* it should be able to view it's contents giving watch expression "(int[N]) arr".

struct Point {
  double x, y, z;

Will be formatted as "(x=<value of x>, y=<value of y>, z=<value of z>)".

Each structure, array and container will be expandable as a tree with access to all it's fields/items.

As per CDT/planning/6.0 there exists bugzilla entry 237960 which can be done by this project.

Other Usability Enhancements

  • Adding a variable/expression watch directly, omitting "Edit expression" dialog box.
  • Hovering mouse over a variable will show its content similar if it was added to expressions watch.
  • Expressions watch will be editable directly, without "Edit expression" dialog box. TODO: screenshot.
  • Rearrange default Debug perspective to reserve more space for code.

TODO: screenshot.

Schedule of Code and Deliverables

Schedule will be finished by 03/29.