break whenever a file (or class) is entered

Question

In Visual Studio, is there any way to make the debugger break whenever a certain file (or class) is entered? Please don't answer "just set a breakpoint at the beginning of every method" :)

I am using C#.

Answer 1

No. Or rather, yes, but it involves setting a breakpoint at the beginning of every method.

Answer 2

Not that I'm aware of. The best you can do is to put a breakpoint in every method in the file or class. What are you trying to do? Are you trying to figure out what method is causing something to change? If so, perhaps a data breakpoint will be more appropriate.

Answer 3

System.Diagnostics.Debugger.Break();

(at the beginning of every method)

Answer 4

Well, as everyone is saying, it involves setting a breakpoint at the beginning of every method. But you're not seeing the bigger picture.

For this to work at all, a breakpoint has to be set at the beginning of every method. Whether you do it manually, or the debugger does it automatically, those breakpoints must be set for this to work.

So, the question really becomes, "If there enough of a need for this functionality, that it is worth building into the debugger an automatic means of setting all those breakpoints?". And the answer is, "Not Really".

Answer 5

Did anyone read the second sentence of my question?

Answer 6

You could write a wrapper method through which you make EVERY call in your app. Then you set a breakpoint in that single method. But... you'd be crazy to do such a thing.

Answer 7

You could start by introducing some sort of Aspect-Oriented Programming - see for instance this explanation - and then put a breakpoint in the single OnEnter method.

Depending on which AOP framework you choose, it'd require a little decoration in your code and introduce a little overhead (that you can remove later) but at least you won't need to set breakpoints everywhere. In some frameworks you might even be able to introduce it with no code change at all, just an XML file on the side?

Answer 8

You could put a memory break point on this, and set it to on read. I think there should be a read most of the time you call a member function. I'm not sure about static functions.

Answer 9

you can use the following macro:

#ifdef _DEBUG
#define DEBUG_METHOD(x) x DebugBreak();
#else
#define DEBUG_METHOD(x) x
#endif

#include <windows.h>

DEBUG_METHOD(int func(int arg) {)
    return 0;
}

on function enter it will break into the debugger

Answer 10

IF this is C++ you are talking about, then you could probably get away with, (a hell of a lot of work) setting a break point in the preamble code in the CRT, or writing code that modifies the preamble code to stick INT 3's in there only for functions generated from the class in question... This, BTW, CAN be done at runtime... You'd have to have the PE file that's generated modify itself, possibly before relocation, to stick all the break's in there...

My only other suggestion would be to write a Macro that uses the predefined macro __FUNCTION__, in which you look for any function that's part of the class in question, and if necessary, stick a

__asm { int 3 }

in your macro to make VS break... This will prevent you from having to set break points at the start of every function, but you'd still have to stick a macro call, which is a lot better, if you ask me. I think I read somewhere on how you can define, or redefine the preamble code that's called per function.. I'll see what I can find.

I would think I similar hack could be used to detect which FILE you enter, but you STILL have to place YOUR function macro's all over your code, or it will never get called, and, well, that's pretty much what you didn't want to do.

Answer 11

You could write a Visual Studio macro that obtained a list of all of the class methods (say, by reading the .map file produced alongside the executable and searching it for the proper symbol names (and then demangling those names)), and then used Breakpoints.add() to programmatically add breakpoints to those functions.

Answer 12

This works fine in WinDbg:

bm exename!CSomeClass::*

(Just to clarify, the above line sets a breakpoint on all functions in the class, just like the OP is asking for, without resorting to CRT hacking or macro silliness)

Answer 13

It sounds like you are looking for a huge horseshoe shaped magnet to change your flat tire.

Answer 14

If you are willing to use a macro then the accepted answer from this question

Should be trivially convertible to you needs by making the search function searching for methods, properties and constructors (as desired), there is also quite possibly a way to get the same information from the the ide/symbols which will be more stable (though perhaps a little more complex).

Answer 15

Use Debugger.Break(); (from the System.Diagnostics namespace)

Put it at the top of each function you wish to have "broken"

void MyFunction()
{
    Debugger.Break();
    Console.WriteLine("More stuff...");
}

Answer 16

Isn't the simplest method to get closest to this to simply set a break point in the constructor (assuming you have only one - or each of them in the case of multiple constructors) ?

This will break into debugging when the class is first instantiated in the case of a non-static constructor, and in the case of a static constructor/class, you'll break into debugging as soon as Visual Studio decides to initialize your class.

This certainly prevents you from having to set a breakpoint in every method within the class.

Of course, you won't continue to break into debugging on subsequent re-entry to the class's code (assuming you're using the same instantiated object the next time around), however, if you re-instantiate a new object each time from within the calling code, you could simulate this.

However, in conventional terms, there's no simple way to set a single break point in one place (for example) and have it break into debugging every time a class's code (from whichever method) is entered (as far as I know).

Answer 17

Assuming that you're only interested in public methods i.e. when the class methods are called "from outside", I will plug Design by Contract once more.

You can get into the habit of writing your public functions like this:

public int Whatever(int blah, bool duh)
{
    // INVARIANT (i)
    // PRECONDITION CHECK (ii)

    // BODY (iii)

    // POSTCONDITION CHECK (iv)
    // INVARIANT (v)

}

Then you can use the Invariant() function that you will call in (i) and set a breakpoint in it. Then inspect the call stack to know where you're coming from. Of course you will call it in (v), too; if you're really interested in only entry points, you could use a helper function to call Invariant from (i) and another one from (v).

Of course this is extra code but

1. It's useful code anyway, and the structure is boilerplate if you use Design by Contract.
2. Sometimes you want breakpoints to investigate some incorrect behaviour eg invalid object state, in that case invariants might be priceless.

For an object which is always valid, the Invariant() function just has a body that returns true. You can still put a breakpoint there.

It's just an idea, it admittedly has a footstep, so just consider it and use it if you like it.

Answer 18

You can use Debugger.Launch() and Debugger.Break() in the assembly System.Diagnostics

Answer 19

Macros can be your friend. Here is a macro that will add a breakpoint to every method in the current class (put the cursor somewhere in the class before running it).

Public Module ClassBreak
    Public Sub BreakOnAnyMember()
        Dim debugger As EnvDTE.Debugger = DTE.Debugger
        Dim sel As EnvDTE.TextSelection = DTE.ActiveDocument.Selection
        Dim editPoint As EnvDTE.EditPoint = sel.ActivePoint.CreateEditPoint()
        Dim classElem As EnvDTE.CodeElement = editPoint.CodeElement(vsCMElement.vsCMElementClass)

        If Not classElem Is Nothing Then
            For Each member As EnvDTE.CodeElement In classElem.Children
                If member.Kind = vsCMElement.vsCMElementFunction Then
                    debugger.Breakpoints.Add(member.FullName)
                End If
            Next
        End If
    End Sub

End Module

Edit: Updated to add breakpoint by function name, rather than file/line number. It 'feels' better and will be easier to recognise in the breakpoints window.

Answer 20

Maybe you could use an AOP framework such as PostSharp to break into the debugger whenever a method is entered. Have a look at the very short tutorial on this page for an example, how you can log/trace whenever a method is entered.

Instead of logging, in your case you could put the Debugger.Break() statement into the OnEntry-handler. Although, the debugger would not stop in your methods, but in the OnEntry-handler (so I'm not sure if this really helps).

Here's a very basic sample:

The aspect class defines an OnEntry handler, which calls Debugger.Break():

[Serializable]
public sealed class DebugBreakAttribute : PostSharp.Laos.OnMethodBoundaryAspect
{
    public DebugBreakAttribute() {}
    public DebugBreakAttribute(string category) {}
    public string Category { get { return "DebugBreak"; } }

    public override void OnEntry(PostSharp.Laos.MethodExecutionEventArgs eventArgs)
    {
     base.OnEntry(eventArgs);
     // debugger will break here. Press F10 to continue to the "real" method
     System.Diagnostics.Debugger.Break();
    }
}

I can then apply this aspect to my class, where I want the debugger to break whenever a method is called:

[DebugBreak("DebugBreak")]
public class MyClass
{
 public MyClass()
 {
  // ...
 }
 public void Test()
 {
  // ...
 }
}

Now if I build and run the application, the debugger will stop in the OnEntry() handler whenever one of the methods of MyClass is called. All I have to do then, is to press F10, and I'm in the method of MyClass.

Answer 21

Mad method using reflection. See the documentation for MethodRental.SwapMethodBody for details. In pseudocode:

void SetBreakpointsForAllMethodsAndConstructorsInClass (string classname)
{
  find type information for class classname
  for each constructor and method
    get MSIL bytes
    prepend call to System.Diagnostics.Debugger.Break to MSIL bytes
    fix up MSIL code (I'm not familiar with the MSIL spec. Generally, absolute jump targets need fixing up)
    call SwapMethodBody with new MSIL
}

You can then pass in classname as a runtime argument (via the command line if you want) to set breakpoints on all methods and constructors of the given class.

Skizz

Answer 22

Files have no existence at runtime (consider that partial classes are no different -- in terms of code -- from putting everything in a single file). Therefore a macro approach (or code in every method) is required.

To do the same with a type (which does exist at runtime) may be able to be done, but likely to be highly intrusive, creating more potential for heisenbugs. The "easiest" route to this is likely to be making use of .NET remoting's proxy infrastructure (see MOQ's implementation for an example of using transparent proxy).

Summary: use a macro, or select all followed by set breakpoint (ctrl-A, F9).

Answer 23

This feature is implemented in VS for native C++. crtl-B and specify the 'function' as "Classname::*", this sets a breakpoint at the beginning of every method on the class. The breakpoints set are grouped together in the breakpoints window (ctrl-alt-B) so they can be enabled, disabled, and removed as a group.

Sadly the macro is likely the best bet for managed code.

Answer 24

Joel, the answer seems to be "no". There isn't a way without a breakpoint at every method.

Answer 25

To remove the breakpoints set by the accepted answer add another macro with the following code

Public Sub RemoveBreakOnAnyMember()
    Dim debugger As EnvDTE.Debugger = DTE.Debugger

    Dim bps As Breakpoints
    bps = debugger.Breakpoints

    If (bps.Count > 0) Then
        Dim bp As Breakpoint
        For Each bp In bps
            Dim split As String() = bp.File.Split(New [Char]() {"\"c})

            If (split.Length > 0) Then
                Dim strName = split(split.Length - 1)
                If (strName.Equals(DTE.ActiveDocument.Name)) Then
                    bp.Delete()
                End If
            End If
        Next
    End If
End Sub