Making Covoar More C++

[Chris Johns]

On 25/3/21 6:54 am, Joel Sherrill wrote:
> 
> 
> On Wed, Mar 24, 2021 at 2:42 PM Gedare Bloom <gedare at rtems.org
> <mailto:gedare at rtems.org>> wrote:
> 
>     On Wed, Mar 24, 2021 at 1:35 PM Joel Sherrill <joel at rtems.org
>     <mailto:joel at rtems.org>> wrote:
>     >
>     > Hi
>     >
>     > There has been a lot of talk about making covoar use more C++
>     > features. It seems to be an issue on every patch. I almost
>     > replied to Gedare's comment at the bottom of a patch
>     > but decided it needed another thread:
>     >
>     > "I still struggle reviewing this codebase, in part because it is C+C++
>     > (TM) and in part because I'm not so proficient in C++ to make concrete
>     > recommendations how to write this better. I think, if the goal is
>     > eventually to make this more C++ like code, then new code coming in
>     > should aim to move the needle in that direction rather than continue
>     > to propagate the old ways of doing."
>     >
>     Thanks for taking this on.
> 
>     > I personally do NOT want to see changes to C++ in one leaf class and
>     > the other architectures not get the same changes. I would prefer to see
>     > all these corrections and base changes in the same style with limited
>     > changes to C-isms. I'm not opposed to the changes but let's take the
>     > Target class one. There are multiple target classes. Changing one
>     > independent of the others isn't a good idea.
>     >
>     This is reasonable to me.
> 
>     > I'd like to see us get a working baseline in and then do something like
>     > sweep std::string through Target* as a single patch. This is easier to
>     > test and review since it would only be C string to std::string. Perhaps
>     > switch to C++ output a file at a time. Redo the report output. Etc.
>     > Discrete chunks instead of piecemeal.
>     >
>     > Covoar has spent years broken and some is from changing working
>     > things to do things "a better way" with no baseline to check against.
>     > We need to get a baseline.
>     >
>     > Please. Let's get a working baseline and then approach this more
>     > methodically. No one is going to suffer from seeing a C string a little
>     > while longer. :)
>     >
>     I'm fine, as long as there is a plan in place and some clear
>     directions. It would help to have tickets to organize the path
>     forward.
> 
>     I'm willing to oblige continued use of C'ism for now, but I want to
>     know the plan and maybe a deadline of sorts by which I can start to be
>     picky again :) I don't like to be in limbo.
> 
> 
> I'd love to have a deadline but I can't guarantee how long Alex can
> work on it. But unless he gets pulled, he can pick on this for a while.

Joel, I pushed a number of changes to move covoar towards C++ back when I pushed
in the ELF and DWARF support. The C++ nature of the interfaces I brought in from
the tool kit required some refactoring. I have not seen much action since then
so Gedare's question seems reasonable.

The need for this code to be C++ and not a mix comes down to what you want to
see happen. There is no real need to move the code closer to C++ other than
improving the technical quality and that is about the life of the code in the
project. If you are willing to look after the code as is then I am fine with
that. If you would like to see the code move to C++ and away from C then can
also happen. It would be an interesting way to learn more about C++.

I find the code hard to work on because I do not know if I am looking at C and
needing to use C solutions or C++ and I should be pulling on C++ threads and
where they go. I also see this is an issue for those working on the code. In
some recent patches I pointed out new code being call from C++ code with C++
objects that was written in C. I pointed this out and the next patch was fine.

> My guess is that C string to std::string is probably a good pass by
> itself since method signatures may change. 

I think anything you feel can be changed and is in reach is welcome.

> There isn't much file input but that could be a pass by itself
> along the way,
> 
> Then sweep output one file at a time leaving reporting for last as
> a batch.
> 
> Do you see an order?

Maybe we organise a group session online where we all look over the code
together and discuss various aspects of the architecture and what it means from
a strictly C vs C++ point of view. Any change like this cannot happen in a
vacuum and I believe C++ is more of a taught language than C. C styles are
easier to pick up  by reading code. My introduction to C++ was in the mid-90's
with a Rational training course and documentation. It takes time to relearn C
solutions you know and have at hand in C++.

I have no idea what we would need to hold such a session and who would be
interested but I am happy to be there and be part of it.

Chris