output=$( eval "$@" )  # Input here is a 'find' command outputting 
a list of files.
     tmp=( ${(f)output} )   # Count lines not characters.
     linecount=$#tmp

... it seems clumsy to create 'tmp' just to count lines, can that be a 
bit more streamlined?  And is it lines or words there?  The output is 
filenames so words=lines in this case but maybe not in other cases so 
I'd like to be sure to have a count of lines.  Easy to get one's 
splitting wrong.


BTW the ultimate in minutiae but the manual says:

12 Conditional Expressions

A /conditional expression/ is used with the [[ compound command to test 
attributes of files and to compare strings. Each expression can be 
constructed from one or more of the following unary or binary expressions:

... and AFAICT the tests work fine with the single '[' as well.