Re: What appears to be inconsistent results from ${(%):-%F{${subscript}}

[Mikael Magnusson <mikachu@gmail.com>]

On 3/4/24, Jim <linux.tech.guy@gmail.com> wrote:
> Hi all,
>
> Output for the  following function will help visualize what I believe to be
> inconsistencies of the output of ${(%):-%F{${subscript}}.
> I would assume %B (background) would yield similar results.
>
> Note the function outputs a solid block character in color.
> Hopefully the block charcter will cut and paste correctly.
>
> color_conversion_check () {
>   local subscript colorconversion
>   local subscripts
>   subscripts=(black blue cyan default gray green grey magenta red white
> yellow
>   bright-blue bright-cyan bright-gray bright-green bright-grey
> bright-magenta
>   bright-red bright-white bright-yellow
>   0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
>   16 17 18 229 230 231
>   232 233 234 253 254 255
>   '#000000' '#007fff' '#ff0080' '#abcdef' '#007FFF' '#FF0080' '#ABCDEF'
>   )
>   print -- "Output of fg associative array"
>   print --  "${fg[gray]}${(r.24..█.)}\e[0m  ${(V)fg[gray]}  fg[gray]"
>   print --  "${fg[grey]}${(r.24..█.)}\e[0m  ${(V)fg[grey]}  fg[grey]"
>   print --
>   for subscript ($subscripts) {
>     colorconversion="${(%):-%F{${subscript}}"
>     print -- "${(%)colorconversion}${(r.24..█.)}\e[0m
>  ${(V)colorconversion}  ${subscript}"
>   }
> }
>
> First, '${(%):-%F{${subscript}}' has unbalanced curly brackets({}), but
> still works.
> Adding a closing bracket(}) results in '}' being added to the output. So
> instead of
> getting ',,,m' you get '...m}'.  I'm confused. What am I missing?

This is a common-ish pitfall. When in double quotes, { and } are not
special to the shell, so the first } matches the opening { from ${.
You then have an extraneous } which is printed as normal.

> To my original point
>
> 1)  the color names grey and gray do not output black but output the
> default

The available colors are: black, red, green, yellow, blue, magenta,
cyan and white.

> 2) bright color names are not converted but output the default color
>     Should bright color names be added to the code?

ANSI only guarantees 8 colors are available.

> 3) using decimal numbers(0-255)
>     0 - 15  uses 30-27 and 90-97(bright) instead of using the colors
> defined
>    by the terminal
>   NOTE: 0-15 are defined even for TERM=linux
>   16-255 uses the colors defined by the terminal
>   Is there a reason why it doesn't use the terminal colors for 0-15?

I have no idea what you mean by this.

-- 
Mikael Magnusson