Re: Mapfile callback access to current line

[Chet Ramey]

On 1/15/11 12:28 AM, Chris F.A. Johnson wrote:
> On Mon, 17 May 2010, Chet Ramey wrote:
> 
>> On 4/15/10 11:56 PM, DennisW wrote:
>>> Mapfile would be that much more powerful if the callback function had
>>> access to the current line. Is there any chance this might be added in
>>> the future?
>>
>> Sure, there's a chance.  What would be the most useful form?  A shell
>> variable that lives for the duration of the execution of the callback
>> function?
> 
>    [A somewhat belated reply!]
> 
>    It appears that the assignment is made after the function is called
>    rather than before. I would like the value passed to the callback
>    function to be the index of the line just read (and already
>    assigned to the array).

Too belated, it seems.  Bash-4.2 passes the line read and to be assigned
to the array element as the second argument to the callback function.
That means that

mapfile -C "echo" -c 1 -t A

numbers the input lines like `cat -n', but starting from 0, and leaves the
result in A.

Chet
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    chet@case.edu    http://cnswww.cns.cwru.edu/~chet/