RE: Coding Style for local variables

["Morten Brørup" <mb@smartsharesystems.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

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.