How to simulate a Delphi breakpoint in code?

Question

I am pretty sure I have seen this before, but I haven't found out / remembered how to do it. I want to have a line of code that when executed from the Delphi debugger I want the debugger to pop-up like there was a break point on that line.

Something like:

FooBar := Foo(Bar);
SimulateBreakPoint; // Cause break point to occur in Delphi IDE if attached
WriteLn('Value: ' + FooBar);

Hopefully that makes sense. I know I could use an exception, but that would be a lot more overhead then I want. It is for some demonstration code.

Thanks in advance!

score 39 · Accepted Answer · edited Oct 02 '08 at 05:47

39

To trigger the debugger from code (supposedly, I don't have a copy of delphi handy to try):

asm int 3 end;

See this page:

http://17slon.com/blogs/gabr/2008/03/debugging-with-lazy-breakpoints.html

edited Oct 02 '08 at 05:47

Jim McKeeth

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answered Oct 02 '08 at 05:25

Joeri Sebrechts

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That was it. Worked great! Thanks! Now I need to find a way to move up the call stack for the break point. . . . – Jim McKeeth Oct 02 '08 at 05:36
Beware to catch EExternal else there will be an external exception while running outside of the debugger. – Toon Krijthe Oct 02 '08 at 06:40
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Or, as I suggested: if DebugHook <> 0 then asm int 3 end; – gabr Oct 02 '08 at 07:26
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I'd usually do "if (DebugHook <> 0) and (**Break Condition**) then asm int 3 end;" so i'd add a condition to break, and put this code right before an error/bug in some conditions. – Osama Al-Maadeed Jun 05 '09 at 17:02

score 14 · Answer 2 · answered Oct 02 '08 at 05:59

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As Andreas Hausladen stated in comments to that artice, Win32 API DebugBreak() function is less DOS-ish and works equally well.

answered Oct 02 '08 at 05:59

gabr

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DebugBreak() puts the break point in the dissassembly/CPU window. I'd rather have it in my code. – Jim McKeeth Oct 02 '08 at 06:11

How to simulate a Delphi breakpoint in code?

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