[Gambas-user] a Debug question

[Doriano Blengino]

Benoît Minisini ha scritto:
>> If  one puts in a breakpoint, and is  stepping through the code one line at
>> a time to check values of variables etc, is there any way or re-setting to
>> a line in the same subroutine prior to the current line you have stopped
>> on.
>>
>> I've found sometimes I'm trying to find a bug, and I put in multiple break
>> points so that I can skip from one to another, and then want to check
>> something in the middle that I've gone past, but have to stop the entire
>> program and start again.
>>     
> Alas you cannot go back in time in debuggers yet. I've heard about people 
> thinking about it, but I don't think you will never see it in Gambas!
>
>   
This is a serious problem, tough. There are programs which, for one 
reason or another, are a little difficult to debug using the internal 
gambas debugger. For example, think at a data-entry form, with a lot of 
controls, each having validation (perhaps, put on top of a database). If 
you want to debug the final action of the form (the Apply button, may 
be), then you have to fill in all the values. Every time you discover a 
bug, even a stupid one, you must restart the program from the beginning; 
and, may be, that form is nested deep in the program logic - you have to 
step through many menus and dialogs to arrive at the point of interest. 
Other times, you don't have a clear idea of the algorithm you have to 
write, so you try again and again. In these situations, the more you can 
do through the debugger, the more time you save.

There could be some improvements to the debugger:

    - the possibility to assign new values to variables (perhaps not the 
structured, but only the simplest ones)
    - the possibility to modify the program text and continue debugging 
(perhaps without adding/deleting lines)
    - the possibility to change the program counter (perhaps with 
constraints)
    - the possibility to add "debug" code, which is compiled in only 
when a special "debug run" is invoked
    - conditional breakpoints / break on the "Nth occurence"

...and may be other which does'nt come to my mind at the moment.

We already discussed a little about this: I know this is somehow hard to 
implement, but having the gambas virtual machine ready in memory should 
help... I mean: if the debugger "knows" how to obtain the value of a 
variable, and how to display it, then perhaps it is possible to 
[relatively] easily assign a new value. Or, the possibility to modify 
the source and continue debugging, seems to me not very hard to do (but 
I could be wrong, of course).

I know that I am biased, because for my work I go deep to the processor 
hardware, and the debugger lets me do nearly everything I want, but you 
could consider whether any improvement could be done to the gambas debugger.

Hope I did'nt annoyed you, they were simply ideas.

Regards,

-- 
Doriano Blengino

"Listen twice before you speak.
This is why we have two ears, but only one mouth."