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Re: defaulting

From: Richard Tobin <richard@inf.ed.ac.uk>
Date: Thu, 28 Jun 2007 15:12:08 +0100 (BST)
To: Norman Walsh <ndw@nwalsh.com>, public-xml-processing-model-wg@w3.org
Message-Id: <20070628141208.5425022906E@macpro.inf.ed.ac.uk>

> Second, I don't want pipeline authors to have to know which ports are
> default inputs and which are not. The current rule is very clear, any
> unbound input port is bound to the default input port.

I think this is prone to error.  If you forget to connect an input,
it won't fail, but you will get the wrong document.  I think omitting
inputs should only work for "natural" flows, where the steps have
an obvious main input and output.

> Changing that rule to something like "Unbound default
> input ports are bound to the default input port while unbound
> non-default input ports are bound to the empty sequence" seems like a
> real step backwards in usability.

I want unbound non-default inputs to be an error.

Consider (as usual) unix pipelines: the | symbol only connects up
the default input and output (stdin and stdout).  If your program
needs input on file descriptor 3 and it's not connected, it will
get an error.

-- Richard
Received on Thursday, 28 June 2007 14:12:18 GMT

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