Re: Justifying text output

[Peter Stephenson <pws@csr.com>]

Thorsten Kampe wrote:
> I wrote a little script[1] that compiles the main zsh config files. Is
> there any way to make the "[ ok ]"/"[ failed ]" messages on the right
> justified?

There are various ways; most involve assigning the variable-length part
of the message to a string.  You should probably not put any escape
characters in there so it doesn't include them in the length
calculation (though if the escape sequences are all the same you would
get away with it).

The standard ksh way is (using a simplified example) to specify left
justification for a parameter:

 typeset -L 40 msg
 for msg in "message one" "a longer message here" "short"; do
 print ${msg} "[ WOW ]"
 done

giving:

 message one                              [ WOW ]
 a longer message here                    [ WOW ]
 short                                    [ WOW ]

You can avoid using the `-L 40' if you change ${msg} to ${(r.40.)msg}.
That's a zsh extension which pads to the given width with spaces.  The
`r' appears instead of `l' because it indicates where the padding goes,
not where the justification is.

However, you can actually get away without assigning the message to a
parameter:

 print ${(r.40.):-"message one"} "WOW"
 print ${(r.40.):-"a longer message here"} "WOW"
 print ${(r.40.):-"short"} "WOW"

giving

 message one                              WOW
 a longer message here                    WOW
 short                                    WOW

That works because zsh treats the absence of a parameter name as an
unset parameter, so it uses the normal logic for :-.  In other words,
`if the length of the parameter is zero, substitute the following string
instead'.   The (r.40.) padding flag works just the same.  You can
include further substitutions in the text, so this would still work in
your case.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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