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- Subject: Re: [Announce] Second Alpha release of a Lua debugger
- From: Steve Heller <steve@...>
- Date: Mon, 16 Apr 2007 00:09:56 -0500
On Mon, 16 Apr 2007 00:10:18 -0500, Rici Lake <firstname.lastname@example.org>
>> 2. How do I actually use breakpoints? I don't seem to be able to get
>> them to do anything. I can set them, but then if I do a "c" to
>> continue, they seem to be ignored. Also, if I call "ldb()" to invoke
>> the debugger, then try to do "s" or "n", I get a message "Not inside
>> breakpoint". Do you have an example of how to use them?
>Yeah, I should have explained that better. The documentation lags the
>code a bit, but I'm trying to finish it all up in my spare time this
>Basically, the easiest way to use breakpoints is to start the program
>you're debugging with the ldb script included in the distro. You just
> ldb myprog.lua #arguments if any
>and it should stop at the first line in myprog.lua. You're then inside
>a breakpoint, and you can use them freely.
That's a lot easier than the way I figured out. Thanks.
>The other way of doing it is to start lua up, load up ldb and ldb-break,
>and manually set a breakpoint. The file you're debugging doesn't
>need to be loaded yet in this case, since breakpoints are identified
>by filename. But the filename has to match character for character;
>ldb includes no file handling code, so it can't tell that ./foo.lua
>and foo.lua are the same file.
>Once you've done that, you can quit ldb and start the file up with
>dofile or require or whatever (but in the case of require, you'll
>definitely have to watch out for the way the filename is entered.)
>I'd like to make it less awkward; I'm still playing with some ideas.
>The reason that it won't let you single step unless you're inside
>a breakpoint is that it needs to be able to work without Lua hooks
>going off. When you're inside a hook handler, hooks are disabled,
>so it can work freely knowing that hooks will be re-enabled when
>it returns to the program. If it wasn't called from a hook handler,
>and it sets the hook handler, the hook will go off before it returns
>to the program.
>I could have gotten around this by running the program in a
>coroutine, which probably would have been a lot easier. However,
>ldb was primarily intended for debugging C modules and embedded
>Lua, and I did not want to create new coroutines inside an
>environment which already used coroutines itself.
Understandably. My situation is probably pretty unusual in running a
"pure Lua" program, with no custom C code underneath.