Re: Coding standards proposal, usage of "this"

[Andrew Burgess <andrew.burgess@embecosm.com>]

* Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> [2021-08-13 10:26:48 -0400]:

> Hi all,
> 
> Here's something I had in mind for a while.  We don't consistently use
> `this` when referring to fields or methods of the current object.  I
> never now if I should use it or not, or point it out in review.  I
> therefore propose these rules so that we have something to refer to.
> 
>  - Use `this` when referring to a data member that is not prefixed by
>    `m_`.  Rationale: without `this`, it's not clear that you are
>    referring to a member of the current class, versus a local or global
>    variable.
>  - Don't use `this` when referring to a data member that is prefixed by
>    `m_`.  Rationale: the prefix already makes it clear that you are
>    referring to a member of the current class, so adding `this` would
>    just add noise.
>  - Use `this` when referring to a method of the current class.
>    Rationale: without `this, it's not clear that you are referring to a
>    method of the current class, versus a free function.
> 
> If we had a convention for how to name internal helper methods, which
> would make it clear that they are methods of the current object and not
> free functions (a bit like `m_` does for data members), we could omit
> `this` when calling such a method.  But we don't have that at the
> moment.

I'd be OK with extending the use of the m_ prefix for private member
functions.  But that wouldn't change the above rules, which all make
sense to me.

Thanks,
Andrew


> 
> A concrete example:
> 
>   int a_global;
> 
>   struct a_struct
>   {
>     int a_method ()
>     {
>       int a_local = 17;
> 
>       return (a_local
> 	      + a_global
> 	      + m_a_private_field
> 	      + this->a_public_field
> 	      + this->a_helper_method ());
>     }
> 
>     int a_public_field;
> 
>   private:
>     int a_helper_method ()
>     {
>       return m_a_private_field;
>     }
> 
>     int m_a_private_field;
>   };
> 
> Any comments?  My intention would be to add this to the coding standards
> on the wiki.
> 
> Simon