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From: Tom Rini <trini@konsulko.com>
To: Simon Glass <sjg@chromium.org>
Cc: Wolfgang Denk <wd@denx.de>,
	U-Boot Mailing List <u-boot@lists.denx.de>,
	Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
	Heinrich Schuchardt <xypron.glpk@gmx.de>,
	Joe Hershberger <joe.hershberger@ni.com>
Subject: Re: [PATCH v8 4/8] env: Allow U-Boot scripts to be placed in a .env file
Date: Tue, 19 Oct 2021 12:30:00 -0400	[thread overview]
Message-ID: <20211019163000.GI7964@bill-the-cat> (raw)
In-Reply-To: <CAPnjgZ0RiiCuOgxce1mRv=GLzadWfvq6cgn0oHeSfhXrCOZR9Q@mail.gmail.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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  reply	other threads:[~2021-10-19 16:30 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-18 18:13 [PATCH v8 0/8] env: Allow environment in text files Simon Glass
2021-10-18 18:13 ` [PATCH v8 1/8] binman: Allow timeout to occur in the image or its section Simon Glass
2021-10-19 14:19   ` Marek Behún
2021-10-31 12:57     ` Simon Glass
2021-10-18 18:13 ` [PATCH v8 2/8] sandbox: Drop distro_boot Simon Glass
2021-10-19 14:20   ` Marek Behún
2021-10-18 18:13 ` [PATCH v8 3/8] doc: Move environment documentation to rST Simon Glass
2021-10-19 14:21   ` Marek Behún
2021-10-18 18:13 ` [PATCH v8 4/8] env: Allow U-Boot scripts to be placed in a .env file Simon Glass
2021-10-19 10:57   ` Wolfgang Denk
2021-10-19 14:07   ` Tom Rini
2021-10-19 14:11     ` Simon Glass
2021-10-19 14:25       ` Tom Rini
2021-10-19 15:31         ` Simon Glass
2021-10-19 16:20           ` Wolfgang Denk
2021-10-19 16:24             ` Simon Glass
2021-10-19 16:30               ` Tom Rini [this message]
2021-10-19 16:39                 ` Simon Glass
2021-10-19 16:44                   ` Tom Rini
2021-10-19 18:21                     ` Simon Glass
2021-10-21  9:10                   ` Wolfgang Denk
2021-10-21  9:05                 ` Wolfgang Denk
2021-10-21  9:02               ` Wolfgang Denk
2021-10-19 16:05       ` Wolfgang Denk
2021-10-19 16:14         ` Simon Glass
2021-10-19 15:57     ` Wolfgang Denk
2021-10-19 15:11   ` Marek Behún
2021-10-18 18:13 ` [PATCH v8 5/8] sandbox: Use a text-based environment Simon Glass
2021-10-19 14:32   ` Marek Behún
2021-10-19 15:52     ` Simon Glass
2021-10-19 16:07       ` Marek Behún
2021-10-18 18:13 ` [PATCH v8 6/8] doc: Mention CONFIG_DEFAULT_ENV_FILE Simon Glass
2021-10-19 14:34   ` Marek Behún
2021-10-19 15:52     ` Simon Glass
2021-10-19 16:07       ` Marek Behún
2021-10-19 18:20         ` Simon Glass
2021-10-18 18:13 ` [PATCH v8 7/8] doc: Improve environment documentation Simon Glass
2021-10-19 14:36   ` Marek Behún
2021-10-18 18:13 ` [PATCH v8 8/8] bootm: Tidy up use of autostart env var Simon Glass
2021-10-19 14:38   ` Marek Behún
2021-10-19 10:48 ` [PATCH v8 0/8] env: Allow environment in text files Wolfgang Denk

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