The Z Shell Manual, zsh/mapfile documentation correction

The Z Shell Manual, zsh/mapfile documentation correction

[Jim]

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Hello,

While working on a zsh script, I researched using module zsh/mapfile to
read a file into an array for further processing.  Trying the example from *The
Z Shell Manual*(Section 22.15) I found that it didn't work as stated.  It
failed to read in blank lines.  I had also noticed an extra element in the
array.

Example:  array=("${(f)mapfile[*filename*]}")

also

egrep -v '^$' filename | wc -l  yielded n lines
print ${#array} yielded n+1 elements

Not that I needed the blank lines, in this case, but it did not read them
into the array.  After some web searching I found that this was discussed
on zsh-users in the 2008 thread *reading a file into an array. mapfile? (f)?
*.  URL:  http://www.zsh.org/mla/users/2008/msg00849.html.  The fix was
actually stated in URL: http://www.zsh.org/mla/users/2008/msg00874.html.

Correction:  array=("${(f@)mapfile[*filename*]}")

The discussion also stated the fact that an extra element(blank) is added
to the end of the array.  It would be nice to have a statement in *The Z
Shell Manual* that the array will contain an additional element.  I'm not
sure I agree that this should be the result, but I'll leave that to others
more knowledgeable about the subject.

Versions of the manual I checked are:
  4.3.17  -- This is also the version of zsh I'm using(OS: Debian Wheezy).
  5.0.2-dev-0

Sincerely,

Jim

Re: The Z Shell Manual, zsh/mapfile documentation correction

[Peter Stephenson]

On Sun, 01 Sep 2013 17:34:38 -0500
Jim <linux.tech.guy@gmail.com> wrote:
> While working on a zsh script, I researched using module zsh/mapfile to
> read a file into an array for further processing.  Trying the example from *The
> Z Shell Manual*(Section 22.15) I found that it didn't work as stated.  It
> failed to read in blank lines.  I had also noticed an extra element in the
> array.
> 
> Example:  array=("${(f)mapfile[*filename*]}")
> 
> also
> 
> egrep -v '^$' filename | wc -l  yielded n lines
> print ${#array} yielded n+1 elements
> 
> Not that I needed the blank lines, in this case, but it did not read them
> into the array.  After some web searching I found that this was discussed
> on zsh-users in the 2008 thread *reading a file into an array. mapfile? (f)?
> *.  URL:  http://www.zsh.org/mla/users/2008/msg00849.html.  The fix was
> actually stated in URL: http://www.zsh.org/mla/users/2008/msg00874.html.
> 
> Correction:  array=("${(f@)mapfile[*filename*]}")
> 
> The discussion also stated the fact that an extra element(blank) is added
> to the end of the array.  It would be nice to have a statement in *The Z
> Shell Manual* that the array will contain an additional element.  I'm not
> sure I agree that this should be the result, but I'll leave that to others
> more knowledgeable about the subject.

diff --git a/Doc/Zsh/mod_mapfile.yo b/Doc/Zsh/mod_mapfile.yo
index 98114ae..96e0568 100644
--- a/Doc/Zsh/mod_mapfile.yo
+++ b/Doc/Zsh/mod_mapfile.yo
@@ -28,9 +28,12 @@ referenced may not be written or deleted.
 
 A file may conveniently be read into an array as one line per element
 with the form
-`var(array)tt(=LPAR()"${(f)mapfile[)var(filename)tt(]}"RPAR())'.
-The double quotes are necessary to prevent empty lines from being
-removed.
+`var(array)tt(=LPAR()"${(f@)mapfile[)var(filename)tt(]}"RPAR())'.
+The double quotes and the `tt(@)' are necessary to prevent empty lines
+from being removed.  Note that if the file ends with a newline,
+the shell will split on the final newline, generating an additional
+empty field; this can be suppressed by using
+`var(array)tt(=LPAR()"${(f@)${mapfile[)var(filename)tt(]%$'\n'}}"RPAR())'.
 )
 enditem()
 
pws