Hi,
On Fri, Apr 3, 2020 at 10:38 PM Zbigniew Jędrzejewski-Szmek
<zbyszek@xxxxxxxxx> wrote:
>
> On Fri, Apr 03, 2020 at 02:23:12PM -0400, Stephen Gallagher wrote:
> > Fabio Valenti made this comment in the FESCo ticket[1].
> >
> > "Side note: I think more people would be amenable to including
> > "conditionals" into their packages if they weren't only shown off as
> > `%if eln this else that`. I think there's more value in doing "feature
> > flags" rather than conditionalize everything based on the `dist` tag,
> > for example something like this might even be useful in fedora
> > branches (e.g. for bootstrapping):
> >
> > ```spec
> > # at the top of the .spec file, where it's easily visible
> > %if 0%{?eln}
> > %bcond_with docs
> > %else
> > %bconf_without docs
> > %endif
> >
> > # ...
> >
> > %if %{with docs}
> > # do something
> > %endif
> > ```
> >
> > This makes conditionals (when they are necessary) much easier to
> > maintain (and understand), in my experience."
>
> This is a side topic, and I didn't want to clutter the FESCo ticket
> with that. But here we have threads, so I hope that you'll forgive me ;)
>
> If find the %bcond_with/%bcond_without pattern abhorrent.
>
> 1. The logic is reversed: when I see "with" I think something is enabled,
> when I see "without" I think something is disabled. But it's actually
> the other way around here, which I find very confusing and often get
> the condition reversed on the first try.
>
> 2. The value ('0%{?eln}') in this example is expressed before the name
> ('docs'), which is like saying 'value =: name'.
>
> 3. It takes five (!) lines to express the something that should be one
> line.
>
> So... could we please get a way to express this in rpm with a sane syntax:
>
> %define_cond docs 0%{?fedora} > 0
I am all for clarity and cleaner syntax.
But I don't think this particular example is a good illustration for
it. If we have more then one switch, or more than one set of switches
it won't work.
Something like:
%if 0%{?fedora} > 0
%define_cond docs 1
%define_cond tests 1
%endif
%if 0%{?rhel} > 0
%define_cond docs 0
%define_cond tests 1
%endif
is more readable than
%define_cond docs 0%{?fedora} > 0
%define_cond tests (0%{?fedora} > 0 OR 0%{?rhel} > 0)
even though there are more lines in it.
>
> (Naming and details of syntax are just examples, but the important
> parts are: one line, name before value, positive logic).
>
> Zbyszek
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--
Aleksandra Fedorova
bookwar
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