Re: zsh ignores the arguments on its first command.

[Martin Buchholz <martinrb@google.com>]

On Thu, Jun 3, 2010 at 02:01, Peter Stephenson <Peter.Stephenson@csr.com> wrote:
> On Wed, 2 Jun 2010 09:44:13 -0700
> Martin Buchholz <martinrb@google.com> wrote:
>> I was thinking that, in addition,
>> the construct ${+NAME}
>> should never cause "unknown parameter",
>> not even due to failure to load a module
>> that provides the parameter as a feature,
>> so an additional fix in the zsh core might be good.
>> If a module fails to load, NAME should become an
>> ordinary unset variable, and ${+NAME} should be 0.
>
> I don't think that can be right.  You're basically asking for all (or a
> substantial subset of) autoload failures to be silent.

I think you're right that users should be notified
of all module load failures, including those
caused by autoloaded features.

However, "unknown parameter" is a very
misleading and frustrating error message,
especially when the construct ${+NAME}
asks to simply return 0 for unknown parameters.

Emacs has a similar feature, and a more
informative error message, of the form

    error ("Autoloading failed to define function %s",

So please change the zsh error to something like

"Autoloading of module %s failed to define parameter %s"

Martin

> To me, the module autoload is a contract that when you reference the
> variable the module *will* be loaded.  If it isn't that's an error.  Take
> the present example: the module failed to load because of an error that (so
> far as I know) we're not interested in.  If this instead failed silently
> the user would simply know that $terminfo wasn't working despite the fact
> they've (maybe implicitly) asked for it and not have a clue why or even
> that something had failed and hence wouldn't know what to do about it.
>
> The autoload interface is a convenience to avoid you having to load modules
> explicitly, which deliberately doesn't expose the module layer directly, so
> necessarily interacts with it simply (load the module on demand, and that's
> it).  If you're paranoid about not having module loads fail you need to do
> more at the zmodload level.
>
> --
> Peter Stephenson <pws@csr.com>            Software Engineer
> Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
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