Short `if'

Short `if'

[Peter Stephenson]

I can't get the short form of `if' to work, described in the manual as:

  if LIST SUBLIST
       A short form of the alternate `if'.

What am I doing wrong?  I don't need it, I just need the code, manual and
tests to be consistent.

% setopt shortloops 
% if true; print hello
if> ^C
% if true { print hello }          # didn't expect this to work
zsh: parse error near `}'
14:55% if true; { print hello }    # shouldn't be dependent on shortloops(?)
if> ^C

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Unit 300, Science Park, Milton Road,
Cambridge, CB4 0XL, UK                          Tel: +44 (0)1223 392070


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Re: Short `if'

[Sven Wischnowsky]

Peter Stephenson wrote:

> I can't get the short form of `if' to work, described in the manual as:
> 
>   if LIST SUBLIST
>        A short form of the alternate `if'.
> 
> What am I doing wrong?  I don't need it, I just need the code, manual and
> tests to be consistent.
> 
> % setopt shortloops 
> % if true; print hello
> if> ^C
> % if true { print hello }          # didn't expect this to work
> zsh: parse error near `}'
> 14:55% if true; { print hello }    # shouldn't be dependent on shortloops(?)
> if> ^C

That's very peculiar.  I don't know either, but

  % if [[ -n x ]] echo hello

works.


Bye
  Sven


-- 
Sven Wischnowsky                         wischnow@informatik.hu-berlin.de

Re: Short `if'

[Oliver Kiddle]

Peter Stephenson wrote:
> 
> I can't get the short form of `if' to work, described in the manual as:

I've never used it so I wouldn't really know.

if { true } print hello

works with shortloops set so maybe that is what is intended and the docs
just need better wording. Ultimately, there needs to be some whay of
knowing when the LIST stops and the SUBLIST starts.

Oliver

RE: Short `if'

[Andrej Borsenkow]

>
> What am I doing wrong?  I don't need it, I just need the code, manual and
> tests to be consistent.
>
> % setopt shortloops
> % if true; print hello
> if> ^C

This is not supposed to work (as long as I can believe docs), shortloops or
no shortloops.

> % if true { print hello }          # didn't expect this to work
> zsh: parse error near `}'

But this should, irrespectively of shortloops (if SUBLIST is of the form
`{ LIST }' or if the SHORT_LOOPS option is set)

> 14:55% if true; { print hello }    # shouldn't be dependent on
> shortloops(?)
> if> ^C
>

Ditto.

-andrej

Re: Short `if'

[Bart Schaefer]

On Jul 5,  2:57pm, Peter Stephenson wrote:
} Subject: Short `if'
}
} I can't get the short form of `if' to work, described in the manual as:
} 
}   if LIST SUBLIST
}        A short form of the alternate `if'.
} 
} What am I doing wrong?

The documentation does explain this:

    The short versions below only work if SUBLIST is of the form
    `{ LIST }' or if the SHORT_LOOPS option is set.  In this case,
    the test part of the loop must also be suitably delimited, such
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    as by `[[ ... ]]' or `(( ... ))', else the end of the test will
    not be recognized.

"In this case" does NOT mean "if the SHORT_LOOPS option is set."  It
should probably say "in either of these cases ..."

If I (dimly) recall correctly, the documentation originally said:

    The short versions below only work if SUBLIST is of the form
    `{ LIST }'.  In this case, ...

And then later the SHORT_LOOPS option was added and the "or if ..." was
stuck into the sentence without fixing the rest of it.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net   

Re: Short `if'

[Peter Stephenson]

"Bart Schaefer" wrote:
> The documentation does explain this:

Maybe this is a bit better.  I think I was partly confused by the fact that
for works happily with no special delimiting in the first group, and partly
the lack of any comment after the particular form of if I was looking at.
I've tried to make it as explicit as possible, because there are bound to
be other equally poor readers.

Index: Doc/Zsh/grammar.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/grammar.yo,v
retrieving revision 1.5
diff -u -r1.5 grammar.yo
--- Doc/Zsh/grammar.yo	2001/06/25 16:07:52	1.5
+++ Doc/Zsh/grammar.yo	2001/07/05 16:59:28
@@ -272,12 +272,17 @@
 Many of zsh's complex commands have alternate forms.  These particular
 versions of complex commands should be considered deprecated and may be
 removed in the future.  The versions in the previous section should be
-preferred instead.  The short versions below only work if var(sublist)
-is of the form `tt({) var(list) tt(})' or if the tt(SHORT_LOOPS)
-option is set.  In this case, the test part of the loop must also be
-suitably delimited, such as by `tt([[ ... ]])' or `tt((( ... )))', else
-the end of the test will not be recognized.
+preferred instead.
 
+The short versions below only work if var(sublist) is of the form `tt({)
+var(list) tt(})' or if the tt(SHORT_LOOPS) option is set.  For the tt(if),
+tt(while) and tt(until) commands, in both these cases the test part of the
+loop must also be suitably delimited, such as by `tt([[ ... ]])' or `tt(((
+... )))', else the end of the test will not be recognized.  For the
+tt(for), tt(repeat), tt(case) and tt(select) commands no such special form
+for the arguments is necessary, but the other condition (the special form
+of var(sublist) or use of the tt(SHORT_LOOPS) option) still applies.
+
 startitem()
 item(tt(if) var(list) tt({) var(list) tt(}) [ tt(elif) var(list) tt({) var(list) tt(}) ] ... [ tt(else {) var(list) tt(}) ])(
 An alternate form of tt(if).  The rules mean that
@@ -296,7 +301,8 @@
 does em(not), since the test is not suitably delimited.
 )
 item(tt(if) var(list) var(sublist))(
-A short form of the alternate `if'.
+A short form of the alternate `if'.  The same limitations on the form of
+var(list) apply as for the previous form.
 )
 item(tt(for) var(name) ... tt(LPAR()) var(word) ... tt(RPAR()) var(sublist))(
 A short form of tt(for).
@@ -312,10 +318,12 @@
 Another form of tt(for).
 )
 item(tt(while) var(list) tt({) var(list) tt(}))(
-An alternative form of tt(while).
+An alternative form of tt(while).  Note the limitations on the form of
+var(list) mentioned above.
 )
 item(tt(until) var(list) tt({) var(list) tt(}))(
-An alternative form of tt(until).
+An alternative form of tt(until).  Note the limitations on the form of
+var(list) mentioned above.
 )
 item(tt(repeat) var(word) var(sublist))(
 This is a short form of tt(repeat).

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Unit 300, Science Park, Milton Road,
Cambridge, CB4 0XL, UK                          Tel: +44 (0)1223 392070


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