Re: [PATCH v8 4/8] env: Allow U-Boot scripts to be placed in a .env file

[Tom Rini <trini@konsulko.com>]

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On Tue, Oct 19, 2021 at 10:24:25AM -0600, Simon Glass wrote:
> Hi Wolfgang,
> 
> On Tue, 19 Oct 2021 at 10:20, Wolfgang Denk <wd@denx.de> wrote:
> >
> > Dear Simon,
> >
> > In message <CAPnjgZ1p6ueRhDsgBZGMXFhgv7UhRFA1UfvoHGGd0-136oTgvA@mail.gmail.com> you wrote:
> > >
> > > But how do we handle this?
> > >
> > > var+=fred
> > >
> > > Is this appending to var or assigning to var+  ?
> >
> > It is assigning to "var+".
> 
> er...
> 
> > >
> > > var++=fred
> > >
> > > is unambiguous but very confusing. I think it would be better to disallow +
> >
> > It's neither unambiguous nor confusing.  It is assigning to "var++".
> 
> What? Can you read that again?

With the assumption that the append operator is "=+" and NOT "+=" then
yes, your examples are unambiguous because = is not allowed in variable
names, before and after.

> > I think we should not change what is old and might be in use.
> >
> > It is much easier to change what is new and can be defined at will.
> >
> > If we define for example that "<name>=+<value>" appends, then we can
> > also define our own escape rules, for example:
> >
> >         var=fred        assigns
> >         var=+fred       appends "fred"
> >         var=\+fred      assignes the value "+fred"
> >         var=++fred      appends "+fred"
> 
> I don't like that at all. It requires an escape for a common case and
> is very confusing.

Wait saying we'll add "+SOMETHING" is a common case?

> Since people will be converting their out-of-tree scripts anyway, they
> can check for this sort of madness at the time. There should be no
> problem.

I'm not sure I like saying the operator is "=+" rather than "+=" because 
"=+" is a less commonly seen operator and tends to be an alternative
appends for special cases / side-effects / position in parsing.

-- 
Tom

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