Re: [gentoo-dev] RFC: Future EAPI version operator changes

[konsolebox]

On Tue, Nov 8, 2016 at 11:47 PM, Michał Górny <mgorny@g.o> wrote:
> On Tue, 8 Nov 2016 10:39:09 -0500
> Michael Orlitzky <mjo@g.o> wrote:
>
>> On 11/08/2016 09:49 AM, Ulrich Mueller wrote:
>> >
>> > This wouldn't completely solve it, because we also have a := slot
>> > operator.
>>
>> Oh, duh...
>>
>>
>> > Brackets would help, or some new separator. Pick your poison:
>>
>> I would really like to have spaces around the infix operators, but then
>> we need to separate the dependencies with a delimiter (like a comma).
>
> Strictly speaking, we don't have to since the lexing should be
> predictable enough. Of course, mistakes like missing version following
> the operator would result in curious errors.
>
> The major problem with spaces I see is that it means we end up having
> an additional [use] block floating following them.

Actually after reading replies from others, I got the idea spaces can
just be made optional, if we use () and {} over & and | (and also have
&& the default function).  Any operator can be a delimiter for itself
or the previous rule:

'dev-foo/bar>=1.3<1.5' is just synonymous to 'dev-foo/bar >= 1.3 <
1.5' or 'dev-foo/bar(>=1.3 <1.5)'.  The beauty there is that it's now
starting to synchronize with the grouping syntax of DEPEND and
RDEPEND.  We would only need to add a space or use grouping if it's
necessary like after using the := operator.

[use] blocks can also be placed anywhere if we only use [] for it, and
use () and {} for grouping versions/slot/repo rules.  And if it would
help, the interpreter can now choose to just interpret/store [use]
block as another condition element with a different class (e.g. use
class) for the sake of simplicity, and restrict it to be only used
once and outside any form of grouping.

There's simplicity in there because you know [] defines flags, while
other operators define version rules.

Btw, & and | can be misused together: dev-foo/bar(condtion & condtion
| condition) and it becomes unclear what comes first before another.
The current DEPEND and RDEPEND syntax avoids it by having && and ||
placed outside of the block.  And if you look at it, () is just
synonymous to '&& ( ... )', and {} is just synonymous to '|| ( ... )'.

-- 
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