RE: Coding Style for local variables

[Konstantin Ananyev <konstantin.ananyev@huawei.com>]

> > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> >
> > 10/06/2024 18:31, Konstantin Ananyev:
> > > Morten said:
> > > > The coding style guide says:
> > > >
> > > > "Variables should be declared at the start of a block of code rather than
> > in the middle. The exception to this is when the variable is
> > > > const in which case the declaration must be at the point of first
> > use/assignment. Declaring variable inside a for loop is OK."
> > > >
> > > > Since DPDK switched to C11, variables can be declared where they are used,
> > which reduces the risk of using effectively uninitialized
> > > > variables. "Effectively uninitialized" means initialized to 0 or NULL
> > where declared, to silence any compiler warnings about the use of
> > > > uninitialized variables.
> > > >
> > > > Can we please agree to remove the recommendation/requirement to declare
> > variables at the start of a block of code?
> > >
> > > I know that modern C standards allow to define variable in the middle.
> > > But I am strongly opposed to allow that in DPDK coding style.
> > > Such practice makes code much harder to read and understand (at least for
> > me).
> >
> > Yes it is convenient to know that all variables are described
> > in a known place, just after function parameters.
> >
> > There is also a consistency concern.
> >
> > Old contributors like to be in a comfort zone,
> > 	and we don't want to lose old contributors.
> > New contributors may be refrained by old rules,
> > 	and we would like to get more new contributors.
> >
> > So that's a tricky decision.
> >
> 
> Independent research shows that readability is improved by declaring local variables as close as possible to their first use:
> https://barrgroup.com/72-initialization#footnote12

Hmm... seems  they don't provide any data to back up their statements.
Specially that one sounds weird for me:
" Too many programmers assume the C run-time will watch out for them, e.g., by zeroing the value of uninitialized variables on system startup."
Why on earth people would assume that?
And what exactly means 'too many? 1%? 10%? 90%? 

> 
> Old people (like myself) need to unlearn their bad old habits (originating from limitations in old C standards), and embrace modern
> methods to reduce the risk of introducing bugs.

Allowing to define variables in the middle of the code by itself wouldn't prevent of use of un-initialized variables.
From other side - compilers are quite good these days to catch such bugs.
So I don't think it is a completing argument..