Re: The amazing array feature in zsh

[Bart Schaefer <schaefer@brasslantern.com>]

On Aug 15,  9:49pm, sac wrote:
}
} I discovered this amazing feature of array recently,
} assigning values just like we do in some high level
} language. 

Gosh, and here all these years I thought the shell *was* a high-level
language. :-)

} Here is a example,
} 
}     files=()      		# initialize to null
}     for mfile in `svn stat $1 | grep '^M' | awk '{
} print $2 }'`
}       do
}       files+=($mfile)
}     done

It gets better ... recent versions of zsh can do this:

    for svncode svnfile in $(svn stat $1)
    do
      case $svncode in
      (M) files+=($svnfile);;
      esac
    done

}     print -c $files      	# print with tabs
} 
} Notice tha assignment to the array variable +=. 

I don't know why this isn't discussed under "Array Parameters".  It
gets a passing mention earlier (as John R. pointed out) but that's
only about scalars.  Then it's mentioned in a different context under
"Subscript Parsing":

    It is possible to avoid the use of subscripts in assignments to
    associative array elements by using the syntax:

        aa+=('key with "*strange*" characters' 'value string')

    This adds a new key/value pair if the key is not already present,
    and replaces the value for the existing key if it is.
 
} And actually this can be iterated like,
}     
}     for file in $files
}     do
}         <do something with $file>
}     done
} 
} I dont know if any other shell provides similar
} feature, but this one is too good and useful, and
} makes the use of array in shell very easy. But I dont
} think this is documented in zsh, atleast I couldn't
} find it.

The behavior as in "for file in $files" context is described in the
"Parameter Expansion" section:

    If NAME is an array parameter, and the KSH_ARRAYS option is not
    set, then the value of each element of NAME is substituted, one
    element per word.  Otherwise, the expansion results in one word
    only; with KSH_ARRAYS, this is the first element of an array. No
    field splitting is done on the result unless the SH_WORD_SPLIT
    option is set.