[libvirt] [PATCH 2/3] docs: hacking: Add good practices for shortening conditional expressions

[Peter Krempa]

On Thu, May 09, 2019 at 12:53:07 +0200, Martin Kletzander wrote:
> On Thu, May 09, 2019 at 12:43:33PM +0200, Peter Krempa wrote:
> > Document that checking if a integer is (non-)zero should (not must)
> > avoid the shortened form that C allows as it may confuse readers into
> > overlooking the other possible values which might be interresting to
> > handle.
> > 
> > While pointers have distinct values from the point of view of the code
> > we only care whether it's non-NULL and thus it's documented it's okay
> > to shorten those.
> > 
> > Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> > ---
> > docs/hacking.html.in | 22 ++++++++++++++++++++++
> > 1 file changed, 22 insertions(+)
> > 
> > diff --git a/docs/hacking.html.in b/docs/hacking.html.in
> > index 081d793360..a2800853ef 100644
> > --- a/docs/hacking.html.in
> > +++ b/docs/hacking.html.in
> > @@ -826,6 +826,28 @@
> >   }
> > </pre>
> > 
> > +    <h2><a id="conditions">Conditional expressions</a></h2>
> > +      <p>For readability reasons new code should avoid shortening comparisons
> > +        to 0 for numeric types. Boolean and pointer comparisions may be
> > +        shortened. All long forms are okay:
> > +      </p>
> > +<pre>
> > +   virFooPtr foos = NULL;
> > +   size nfoos = 0;
> > +   bool hasFoos = false;
> > +
> > +GOOD:
> > +    if (!foos)
> > +    if (!hasFoos)
> > +    if (nfoos == 0)
> > +    if (foos == NULL)
> > +    if (hasFoos == true)
> > +
> > +BAD:
> > +    if (!nfoos)
> > +    if (foos)
> 
> why is this bad when it is a pointer?  Typo?

Oops, yes. This was supposed to be "if (nfoos)"
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