question about parameter expansion

question about parameter expansion

[Dmitri Vereshchagin]

Hello.

Here is a code sample I would like to rewrite using parameter expansion

  if (( ${+foo} )); then
    bar=
  else
    bar=baz
  fi

Cannot find it in the docs, but I suppose there is a way to do that.  Am
I right?

Thanks.

-- 
Dmitri Vereshchagin

Re: question about parameter expansion

[Mikael Magnusson]

On Sat, Sep 26, 2015 at 12:18 PM, Dmitri Vereshchagin
<dmitri.vereshchagin@gmail.com> wrote:
> Hello.
>
> Here is a code sample I would like to rewrite using parameter expansion
>
>   if (( ${+foo} )); then
>     bar=
>   else
>     bar=baz
>   fi
>
> Cannot find it in the docs, but I suppose there is a way to do that.  Am
> I right?
>
> Thanks.
>
> --
> Dmitri Vereshchagin

You have to think outside the box for this one,
bar=${${${+foo}#1}//0/baz}

-- 
Mikael Magnusson

Re: question about parameter expansion

[ZyX]

26.09.2015, 16:38, "Mikael Magnusson" <mikachu@gmail.com>:
> On Sat, Sep 26, 2015 at 12:18 PM, Dmitri Vereshchagin
> <dmitri.vereshchagin@gmail.com> wrote:
>>  Hello.
>>
>>  Here is a code sample I would like to rewrite using parameter expansion
>>
>>    if (( ${+foo} )); then
>>      bar=
>>    else
>>      bar=baz
>>    fi
>>
>>  Cannot find it in the docs, but I suppose there is a way to do that. Am
>>  I right?
>>
>>  Thanks.
>>
>>  --
>>  Dmitri Vereshchagin
>
> You have to think outside the box for this one,
> bar=${${${+foo}#1}//0/baz}

Why not simply

    bar=${foo+baz}

?

>
> --
> Mikael Magnusson

Re: question about parameter expansion

[Mikael Magnusson]

On Sat, Sep 26, 2015 at 7:41 PM, ZyX <kp-pav@yandex.ru> wrote:
> 26.09.2015, 16:38, "Mikael Magnusson" <mikachu@gmail.com>:
>> On Sat, Sep 26, 2015 at 12:18 PM, Dmitri Vereshchagin
>> <dmitri.vereshchagin@gmail.com> wrote:
>>>  Hello.
>>>
>>>  Here is a code sample I would like to rewrite using parameter expansion
>>>
>>>    if (( ${+foo} )); then
>>>      bar=
>>>    else
>>>      bar=baz
>>>    fi
>>>
>>>  Cannot find it in the docs, but I suppose there is a way to do that. Am
>>>  I right?
>>>
>>>  Thanks.
>>>
>>>  --
>>>  Dmitri Vereshchagin
>>
>> You have to think outside the box for this one,
>> bar=${${${+foo}#1}//0/baz}
>
> Why not simply
>
>     bar=${foo+baz}
>
> ?

The main reason would be that it doesn't do what OP asked for.

-- 
Mikael Magnusson

Re: question about parameter expansion

[Dmitri Vereshchagin]

* Mikael Magnusson <mikachu@gmail.com> [2015-09-26 16:37]:
> You have to think outside the box for this one,
> bar=${${${+foo}#1}//0/baz}

I thought that there is more concise way like some sort of ${name+word}
counterpart.  Thank you.

-- 
Dmitri Vereshchagin

Re: question about parameter expansion

[Mikael Magnusson]

On Sat, Sep 26, 2015 at 8:08 PM, Dmitri Vereshchagin
<dmitri.vereshchagin@gmail.com> wrote:
> * Mikael Magnusson <mikachu@gmail.com> [2015-09-26 16:37]:
>> You have to think outside the box for this one,
>> bar=${${${+foo}#1}//0/baz}
>
> I thought that there is more concise way like some sort of ${name+word}
> counterpart.  Thank you.

Here's another variant, which may or may not be considered more
concise (it happens to be the exact same number of characters, but
uses fewer things, and probably doesn't work under ksh_arrays, but
then, what does, commas abounds),

bar=${${:-baz}[1,$+foo-1]}

-- 
Mikael Magnusson

Re: question about parameter expansion

[Dmitri Vereshchagin]

* Mikael Magnusson <mikachu@gmail.com> [2015-09-26 21:34]:
> Here's another variant, which may or may not be considered more
> concise (it happens to be the exact same number of characters, but
> uses fewer things, and probably doesn't work under ksh_arrays, but
> then, what does, commas abounds),
> 
> bar=${${:-baz}[1,$+foo-1]}

Nice.  Seems like there is another alternative

bar=${${foo-baz}#$foo}

-- 
Dmitri Vereshchagin

Re: question about parameter expansion

[Ray Andrews]

On 09/26/2015 11:57 AM, Dmitri Vereshchagin wrote:
> * Mikael Magnusson <mikachu@gmail.com> [2015-09-26 21:34]:
>> Here's another variant, which may or may not be considered more
>> concise (it happens to be the exact same number of characters, but
>> uses fewer things, and probably doesn't work under ksh_arrays, but
>> then, what does, commas abounds),
>>
>> bar=${${:-baz}[1,$+foo-1]}
> Nice.  Seems like there is another alternative
>
> bar=${${foo-baz}#$foo}
>
Where is this sort of thing discussed in the manual?
It is so often the case that I want to research something
but I don't know where to look. Getting the basic terminology
strait helps--I'd have thought the above was 'variable tests'
or something like that, not 'parameter expansion' cuz I take
parameter to refer to command arguments.  In any case looking
for 'parameter expansion' in the index is no help.  Getting
the overall grammatical terminology still eludes me.  'Variable'
doesn't exist in the index at all and so I run out of ideas.

Re: question about parameter expansion

[Bart Schaefer]

On Sep 26,  2:11pm, Ray Andrews wrote:
}
} Where is this sort of thing discussed in the manual?

Under "Parameter Expansion".

Perhaps unfortunately, you need to get familar with shell language
terminology.  The strings $1, $2, etc. are referred to as "positional
parameters" whereas $a, $foo, $PATH, etc. are "named parameters".
The signifier "$" is said to introduce an expansion.  (It used to
be that it only introduced a parameter expansion, and parts of the
doc still talk about it that way, but now it also introduces other
expansions like command substitution and arithmetic.)

The word "variable" is usually a synonym for "named parameter," but
might also refer to named strings in the process environment, which
can be referenced as if they were named parameters.

} In any case looking for 'parameter expansion' in the index is no help.

This is a thing about the yodl/info documentation model that I don't
like.  I think all the (sub)section headings should be in the index.
Instead the section headings are in "menus" (which don't show up at all
in the manpage-formatted documentation) and you can't find them with an
index search.

In this specific case, though, "parameter expansion" does appear in the
index, along with "parameter expansion flags", "parameter modifiers",
etc.  How were you searching the index?

} 'Variable' doesn't exist in the index at all

??

* variables:                             Parameters.         (line    6)
* variables, environment:                Parameters.         (line   25)

Again, exactly how are you searching what index?  Have you tried always
searching case-insensitively?

Re: question about parameter expansion

[Ray Andrews]

On 09/26/2015 02:34 PM, Bart Schaefer wrote:
> On Sep 26,  2:11pm, Ray Andrews wrote:
> }
> } Where is this sort of thing discussed in the manual?
>
> Under "Parameter Expansion".

Ooops ... My eye caught 'parameters, expanding', but  see there is indeed
'parameter expansion' as well.  That's a bit lazy of me.
>
> Perhaps unfortunately, you need to get familar with shell language
> terminology.
Yes.
> The strings $1, $2, etc. are referred to as "positional
> parameters" whereas $a, $foo, $PATH, etc. are "named parameters".
> The signifier "$" is said to introduce an expansion.  (It used to
> be that it only introduced a parameter expansion, and parts of the
> doc still talk about it that way, but now it also introduces other
> expansions like command substitution and arithmetic.)
>
> The word "variable" is usually a synonym for "named parameter," but
> might also refer to named strings in the process environment, which
> can be referenced as if they were named parameters.

Without exaggeration that's the most useful minute of reading I've done 
as to
zsh so far.  If I'd read that two years ago it would have saved me hours 
of grief.

>
> } In any case looking for 'parameter expansion' in the index is no help.
>
> This is a thing about the yodl/info documentation model that I don't
> like.  I think all the (sub)section headings should be in the index.
> Instead the section headings are in "menus" (which don't show up at all
> in the manpage-formatted documentation) and you can't find them with an
> index search.

When all else fails, an excellent index comes to the rescue.  An 
excellent glossary
is as valuable.

>
> In this specific case, though, "parameter expansion" does appear in the
> index, along with "parameter expansion flags", "parameter modifiers",
> etc.  How were you searching the index?
>
> } 'Variable' doesn't exist in the index at all
>
> ??
>
> * variables:                             Parameters.         (line    6)
> * variables, environment:                Parameters.         (line   25)
>
> Again, exactly how are you searching what index?  Have you tried always
> searching case-insensitively?

U
     umask    17. Shell Builtin Commands
     Unicode combining characters    16.2.12 Zle
     unset parameters, substituting    16.2.3 Expansion and Globbing
     until loops    6.3 Complex Commands
     user contributions    26. User Contributions
     user selection    6.3 Complex Commands
     users, watching    17. Shell Builtin Commands

V
     version                                    The Z Shell Manual
     version control utility            26.4 Gathering information from 
version control systems

W
     waiting before rm *

... pardon the busted formatting, but that's the Index as I see it. Am I 
barking up the
wrong tree somehow?

Re: question about parameter expansion

[Bart Schaefer]

On Sep 26,  3:02pm, Ray Andrews wrote:
}
} > Again, exactly how are you searching what index?  Have you tried always
} > searching case-insensitively?
} 
} V
}      version                                    The Z Shell Manual
}      version control utility            26.4 Gathering information from 
} version control systems


By process of elimination I've determined, in spite of you not answering
my question, that you're looking at the HTML documentation, probably on
www.zsh.org.

Last modified: 2014-01-07

It's puzzling that the "Concept Index" pages haven't been updated since
January 2014 given that the rest of the manual was supposedly rebuilt
last October, but either way it's a year or more out of date.  You might
try using the manuals that go with your local build.

Who has access to rebuild the docs on the web?  Simon, are you out there?

  This document was generated by Simon Ruderich on October 11, 2014 using
  texi2html 1.82.
  Zsh version 5.0.7, released on October 7, 2014.

Re: question about parameter expansion

[Ray Andrews]

On 09/27/2015 09:58 AM, Bart Schaefer wrote:
>
> By process of elimination I've determined, in spite of you not answering
> my question,

I glossed over it because in the doc there seems to be nothing that 
indicates
the ability to be case sensitive or not.  The index seems to just be 
what it is.
> that you're looking at the HTML documentation, probably on
> www.zsh.org.

Yup.  I take it on faith that that would be the most current.  I expect 
that when
modifications take place, it's there first and thence it makes it's way 
into
releases.  There has to be a master somewhere, no?
>
> Last modified: 2014-01-07
>
> It's puzzling that the "Concept Index" pages haven't been updated since
> January 2014 given that the rest of the manual was supposedly rebuilt
> last October, but either way it's a year or more out of date.  You might
> try using the manuals that go with your local build.

Nuts I had no idea there was any such thing.  I've man pages of course 
but no HTML.
Where is it to be found?

Re: question about parameter expansion

[ZyX]

27.09.2015, 21:30, "Ray Andrews" <rayandrews@eastlink.ca>:
> On 09/27/2015 09:58 AM, Bart Schaefer wrote:
>>  By process of elimination I've determined, in spite of you not answering
>>  my question,
>
> I glossed over it because in the doc there seems to be nothing that
> indicates
> the ability to be case sensitive or not. The index seems to just be
> what it is.
>>  that you're looking at the HTML documentation, probably on
>>  www.zsh.org.
>
> Yup. I take it on faith that that would be the most current. I expect
> that when
> modifications take place, it's there first and thence it makes it's way
> into
> releases. There has to be a master somewhere, no?
>>  Last modified: 2014-01-07
>>
>>  It's puzzling that the "Concept Index" pages haven't been updated since
>>  January 2014 given that the rest of the manual was supposedly rebuilt
>>  last October, but either way it's a year or more out of date. You might
>>  try using the manuals that go with your local build.
>
> Nuts I had no idea there was any such thing. I've man pages of course
> but no HTML.
> Where is it to be found?

Depends on the distribution, it may choose to remove them. If it did not, most likely somewhere in /usr/share/doc I think. Gentoo has this in /usr/share/doc/zsh-{version}/html assuming zsh built with USE=doc.

Re: question about parameter expansion

[Simon Ruderich]

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On Sun, Sep 27, 2015 at 09:58:46AM -0700, Bart Schaefer wrote:
> [snip]
>
> Who has access to rebuild the docs on the web?  Simon, are you out there?
>
>   This document was generated by Simon Ruderich on October 11, 2014 using
>   texi2html 1.82.
>   Zsh version 5.0.7, released on October 7, 2014.

Hello,

Sorry for the late response. Just updated it for 5.1.1.

Regards
Simon
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+ using gnupg http://gnupg.org
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Re: question about parameter expansion

[Ray Andrews]

On 10/02/2015 07:10 AM, Simon Ruderich wrote:
> Sorry for the late response. Just updated it for 5.1.1. Regards Simon 

This seems up to date:

http://zsh.sourceforge.net/Doc/Release/index.html#Top

... But this still refers to 5.0.7:

http://zsh.sourceforge.net/Doc/Release/zsh.html#Top

... both show the Index page which is got to via '[Top]'.

Re: question about parameter expansion

[Simon Ruderich]

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On Fri, Oct 02, 2015 at 09:35:45AM -0700, Ray Andrews wrote:
> On 10/02/2015 07:10 AM, Simon Ruderich wrote:
>>Sorry for the late response. Just updated it for 5.1.1. Regards Simon
>
> This seems up to date:
>
> http://zsh.sourceforge.net/Doc/Release/index.html#Top
>
> ... But this still refers to 5.0.7:
>
> http://zsh.sourceforge.net/Doc/Release/zsh.html#Top
>
> ... both show the Index page which is got to via '[Top]'.

Hello,

Hm. It seems to be an old file. Where did you find a link
pointing to it?

Regards
Simon
-- 
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+ using gnupg http://gnupg.org
+ public key id: 0x92FEFDB7E44C32F9

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Re: question about parameter expansion

[Ray Andrews]

On 10/02/2015 12:07 PM, Simon Ruderich wrote:
>
> ... But this still refers to 5.0.7:
>
> http://zsh.sourceforge.net/Doc/Release/zsh.html#Top
>
> ... both show the Index page which is got to via '[Top]'.
> Hello,
>
> Hm. It seems to be an old file. Where did you find a link
> pointing to it?
I've had it bookmarked for ages.  Apart from the URL itself, I can't 
remember
how I got to it except to say that it would have been 'normal'. Since 
it's at
sourceforge I'd expect it to 'disappear' as far as making itself sound like
it's the latest version--but that's up to you guys.

latest manual

[Ray Andrews]

On 10/02/2015 12:50 PM, Ray Andrews wrote:
> On 10/02/2015 12:07 PM, Simon Ruderich wrote:
>>
>> ... But this still refers to 5.0.7:
>>
>> http://zsh.sourceforge.net/Doc/Release/zsh.html#Top
>>
>> ... both show the Index page which is got to via '[Top]'.
>> Hello,
>>
>> Hm. It seems to be an old file. Where did you find a link
>> pointing to it?
> I've had it bookmarked for ages.  Apart from the URL itself, I can't 
> remember
> how I got to it except to say that it would have been 'normal'. Since 
> it's at
> sourceforge I'd expect it to 'disappear' as far as making itself sound 
> like
> it's the latest version--but that's up to you guys.
>
If I hit '[top]' I seem to always go back to '5.0.7'.  And going to the 
index
I seem to get lost sometimes too--sometimes the index contains 'variable'
(which was missing in 5.0.7) and sometimes not, so wires seem to be
crossed there.

Re: latest manual

[Ray Andrews]

On 10/02/2015 01:03 PM, Ray Andrews wrote:
> If I hit '[top]' I seem to always go back to '5.0.7'.  And going to 
> the index
> I seem to get lost sometimes too--sometimes the index contains 'variable'
> (which was missing in 5.0.7) and sometimes not, so wires seem to be
> crossed there.
>
>
This is the new 'V' index:

http://zsh.sourceforge.net/Doc/Release/Concept-Index.html#Concept-Index-1_cp_letter-V


This is the old 'V' index:
http://zsh.sourceforge.net/Doc/Release/zsh_31.html#index_split-3_cp_letter-V

It could be related to browsers somehow, because Firefox seems to get it 
right
and Opera to go off the rails. Something to do with the 'split' it seems.

Re: latest manual

[Bart Schaefer]

Clear your broswer cache in Opera?

And delete that old bookmark.  Yeah, we ought to discard the entire
old website contents and recreate only the valid new stuff, but ...

Re: latest manual

[Andrew Janke]

On 10/2/15 4:23 PM, Ray Andrews wrote:
> On 10/02/2015 01:03 PM, Ray Andrews wrote:
>> If I hit '[top]' I seem to always go back to '5.0.7'.  And going to 
>> the index
>> I seem to get lost sometimes too--sometimes the index contains 
>> 'variable'
>> (which was missing in 5.0.7) and sometimes not, so wires seem to be
>> crossed there.
>>
>>
> This is the new 'V' index:
>
> http://zsh.sourceforge.net/Doc/Release/Concept-Index.html#Concept-Index-1_cp_letter-V 
>
>
>
> This is the old 'V' index:
> http://zsh.sourceforge.net/Doc/Release/zsh_31.html#index_split-3_cp_letter-V 
>
>
> It could be related to browsers somehow, because Firefox seems to get 
> it right
> and Opera to go off the rails. Something to do with the 'split' it seems.
>
>
Did you clear your browser caches? They're static pages at the same URLs 
as before (as opposed to a redirect to specific versions). My main 
browser, Firefox, kept showing the 5.0.7 until I manually cleared its 
cache. After clearing, I see the new manual under all browsers.

Re: latest manual

[Ray Andrews]

On 10/02/2015 01:53 PM, Bart Schaefer wrote:
> Clear your broswer cache in Opera?
Bingo.  Sheesh, how long do those sub-pages get stored?
The cache is supposta check for updates every five minutes.
Since the primary URL got updated I never thought to
worry about the rest.  Dunno.
> And delete that old bookmark.
Did, but no joy.  Anyway killing the cache did the trick. Tho
it still seems strange it should be needed.  But Thunderturkey
did it right so it must be an Opera issue.


Bart, no advice on how to get curses.so to build?

Re: latest manual

[Simon Ruderich]

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On Fri, Oct 02, 2015 at 01:53:38PM -0700, Bart Schaefer wrote:
> And delete that old bookmark.  Yeah, we ought to discard the entire
> old website contents and recreate only the valid new stuff, but ...

The release script already takes care of deleting the old stuff.

I just forgot to add a --delete to the rsync command line when
uploading it to the website. I've run it with --delete and
updated the README.

Regards
Simon
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Re: latest manual

[Bart Schaefer]

On Oct 2,  2:55pm, Ray Andrews wrote:
} Subject: Re: latest manual
}
} Bingo.  Sheesh, how long do those sub-pages get stored?
} The cache is supposta check for updates every five minutes.

The server is supposed to advertise a cache expiration time.  If none
is stated, the browser can keep the page cached as long as it chooses.
It appears Opera chose "forever".

It might be possible to update the zsh website to start advertising a
shorter expiration time.