Re: What's the 'word' in parameter relpacement expansion?

[Han Pingtian <hanpt@xxxxxxxxxxxxxxxxxx>]

On Fri, Nov 04, 2016 at 10:24:25AM +0000, Peter Stephenson wrote:
> On Fri, 4 Nov 2016 17:00:09 +0800
> Han Pingtian <hanpt@xxxxxxxxxxxxxxxxxx> wrote:
> > I think
> > 
> > $ a='abc def'
> > $ print ${a:/def}
> > 
> > will get 'abc ', but it is 'abc def'. So it works just like ${a//#%def}?
> > The 'entire word' in the document is the same thing of 'entire string'?
> 
> "Word" isn't a very good word, but I'm not sure what would be better.
> 
> In this context, what it means is either a complete scalar value,
> or an element of an array.  There is an option to use space-delimited
> words in substitution, but it's not the default (and I don't think it's
> all that commonly used as array processing tends to be more useful).
> 
> Hence
> 
> % a=(abc def)
> % print ${a:/def}
> abc
> % a=(abc "abc def")
> % print ${a:/def}
> abc abc def
> 
> More widely in the documentation, it's treated as synonymous with a
> single command line argument.  That's what it means in "history word",
> and I think that's what's inspired the usage here, although it's
> confused by the many ways of getting words explicitly or implicitly
> split.
> 
> If we can find something unambiguous we can change it generally, though
> it'll need a lot of editing.
> 
> The best we've got at the moment is this in paramater substitution
> documentation:
> 
> 
> If var(name) is an array parameter, and the tt(KSH_ARRAYS) option is not
> set, then the value of each
> element of var(name) is substituted, one element per word.  Otherwise, the
> expansion results in one word only; with tt(KSH_ARRAYS), this is the first
> element of an array.  No field splitting is done on the result unless the
> tt(SH_WORD_SPLIT) option is set.
> See also the flags tt(=) and tt(s:)var(string)tt(:).
> 
> 
> We could add something like the following, though it slightly overlaps
> with what I've just quoted.
> 
> pws
> 
> diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo
> index b731516..f465b2f 100644
> --- a/Doc/Zsh/expn.yo
> +++ b/Doc/Zsh/expn.yo
> @@ -572,6 +572,18 @@ noderef(Modifiers) in noderef(History Expansion) can be
>  applied:  for example, tt(${i:s/foo/bar/}) performs string
>  substitution on the expansion of parameter tt($i).
> 
> +In the following descriptions, `word' refers to a single word
> +substituted on the command line, not necessarily a space delimited word.
> +With default options, after the assignments:
> +
> +example(array=("first word" "second word")
> +scalar="only word")
> +
> +then tt($array) substitutes two words, `tt(first word)' and `tt(second
> +word)', and tt($scalar) substitutes a single word `tt(only word)'.  This
> +may be modified by explicit or implicit word-splitting, however.  The
> +full rules are complicated and are noted at the end.
> +
>  startitem()
>  item(tt(${)var(name)tt(}))(
>  The value, if any, of the parameter var(name) is substituted.

Thanks. So ':/' is the same thing of '/#%'? It looks like a kind of
redundance.