Re: Gnat 2013 is out!

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Fri, 31 May 2013 18:12:29 +0200, <dptrash@arcor.de> a écrit:

> May I ask, how you debug Ada programs? Do you use GNATbench 2.7 for  
> that? I need a good debugging tool :-)

I personally did not used a debugger since Borland Turbo Pascal. I first  
missed it (at that time GDB for C programs had issues on Windows 3.1), but  
quickly figured a debugger only show you one particular path in your  
logic, and above all, consume a lot of your time to just follow this path,  
a lot of time which is not used to understand the properties of the whole.

So instead of trying to fix something in a particular path — ignoring the  
whole and so probably introducing a new bug elsewhere in the while — I  
would say it's surely better to understand the whole and so not rely on a  
debugger. A debugger never gives you such a picture, only analysis and  
understand gives this to you.

When something really drives me crazy, I just add a “sentinel” which  
prints out some information (just requires an “with Ada.Text_IO” and a  
line added somewhere to print an “Element'Image”) I fill to not track  
correctly, to help me a bit. Then, back to global understanding as soon as  
possible.

A program is not a single path and a particular property of a particular  
state as exposed by a debugger, it's multitude of possible paths and  
general properties common to a multitude of possible states (that's what  
you have to track, not a single path). In short, a debugger gives you a  
wrong picture, except if you are at the very beginning and try to figure  
out what's a programming language and how a state machine (like a computer  
is) works.

Another issue, is that a program is not always running in a debugger, and  
so what when something went wrong while it was not running in a debugger  
and you don't have a complete and exact snapshot of the program's state  
when it get wrong? Here, a logger surely help more than a debugger, as it  
may be active all the time (most platform provides an API to help  
automatically manage logs and avoid these logs to fill all of your storage  
space).


-- 
“Syntactic sugar causes cancer of the semi-colons.” [1]
“Structured Programming supports the law of the excluded muddle.” [1]
[1]: Epigrams on Programming — Alan J. — P. Yale University