Re: triviality regarding $# counts

[Ray Andrews <rayandrews@eastlink.ca>]

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On 2024-04-11 21:55, Lawrence Velázquez wrote:

> If eval really is necessary (to be frank, I don't trust your judgment
> on this), show us examples that require it, instead of the misleading
> Rube Goldberg machines you've been offering.
I don't trust it neither, and I taught Rube everything he knows. 
Seriously, you won't sympathize, but the tinkerer's approach was the 
only one available to me at least until I had enough ad hoc code built 
up that sorta works to begin to start to try to understand it formally.  
And my efforts to find patterns of behavior -- as you know better than 
anyone -- lead me to false conclusions all the time.  The manual is 
useless as pedagogy.  If there was 'zsh school' I'd enroll and learn my 
shell ABC's properly from the ground up. But there isn't.  So I hack 
away.  But please understand I *hate* being me.  I like competence :(
> The count is correct by accident.  Your unquoted command substitution
> drops the two empty lines but splits the two lines you say should not
> be split.
Right, I'm aware of that possibility at least in theory.  Word splitting 
lurks.
> 	% orig='abc
> 	quote>
> 	quote> def ghi
> 	quote> jkl mno
> 	quote>
> 	quote> pqr'
> 	% arr=($(print -r -- $orig))
> 	% typeset -p arr
> 	typeset -a arr=( abc def ghi jkl mno pqr )
It will take me a long time to understand that.

> 	% cat foo.zsh
> 	orig='abc
>
> 	def ghi
> 	jkl mno
>
> 	pqr'
>
> 	# The sensible way to split on LFs.
> 	#arr=("${(@f)orig}")
>
> 	# A very silly way to split on LFs.  Use double quotes to
> 	# prevent the result of $(...) from being split and to retain
> 	# empty words in the result of ${(@)...}.
> 	arr=("${(@f)$(print -r -- $orig)}")
>
> 	typeset -p arr
> 	print -r -- $#arr
>
> 	# Use double-quoted $arr[@] to retain empty elements.  Use
> 	# "print -C1" to avoid printing an empty line if "arr" is empty.
> 	print -rC1 -- "$arr[@]"
>
> 	% zsh ./foo.zsh
> 	typeset -a arr=( abc '' 'def ghi' 'jkl mno' '' pqr )
> 	6
> 	abc
>
> 	def ghi
> 	jkl mno
>
> 	pqr
> 	%
I think I can chew on that, backatcha later.

> You both populate and print your array incorrectly. For the umpteenth
> time, you should use "typeset -p" to inspect your variables' values.
>
I keep typeset -p close at all times now.  But there are times when I'm 
still baffled.  Like an alchemist.  Sheesh, just yesterday I was 
attempting to transform this:

typeset -g var="
abc

     def ghi
     jkl mno

     pqr
"

... into an array that retained the same 'shape' -- that prints verbatim 
-- and typeset -p showed newlines being transubstantiated into dollar 
signs!  God knows how.

For now, what I'm wishing for is a nice, focused essay: "How to use '$#' 
to count whatever it is you want to count -- characters, words, lines, 
paragraphs (at one point my count was '3' which I'd approximate to being 
a paragraph) ... and all with or without spaces and/or empty lines. " 
Should run about  ten pages but it would be everything there is to know 
about '$#'.


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