Build a variable name from another variable?

Build a variable name from another variable?

[Omen Wild]

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I am not totally sure what it is called, but I want to build a variable
name dynamically, from the contents of another variable.  That is, I
have:

----- Begin script -----
barcontents="bar contents"
baz="bar"

echo $barcontents # <---- effect I want
echo ${${baz}contents} # <---- how I want to get there
----- End script -----

I get this error: bad substitution

I think the answer involves the (P) flag, as in:
echo ${${(P)baz}contents}

But that dies with the same error.

I am running Debian unstable, zsh version 4.0.9.

Thanks,
   Omen

-- 
I used up all my sick days, so I'm calling in dead.

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Re: Build a variable name from another variable?

[Philippe Troin]

Omen Wild <Omen.Wild@Dartmouth.EDU> writes:

> I am not totally sure what it is called, but I want to build a variable
> name dynamically, from the contents of another variable.  That is, I
> have:
> 
> ----- Begin script -----
> barcontents="bar contents"
> baz="bar"
> 
> echo $barcontents # <---- effect I want
> echo ${${baz}contents} # <---- how I want to get there
> ----- End script -----

% t="${baz}contents"   
% echo ${${(P)t}}
bar contents

Works...
i could not manage to do it without an intermediate variable.

Phil.

Re: Build a variable name from another variable?

[Cosmo]

Omen Wild wrote:
> 
> 
> 
> I am not totally sure what it is called, but I want to build a variable
> name dynamically, from the contents of another variable.  That is, I
> have:
> 
> ----- Begin script -----
> barcontents="bar contents"
> baz="bar"
> 
> echo $barcontents # <---- effect I want
> echo ${${baz}contents} # <---- how I want to get there
> ----- End script -----
> 
> I get this error: bad substitution
> 
> I think the answer involves the (P) flag, as in:
> echo ${${(P)baz}contents}

Back in the old days, before these fancy complicated shells, I'd just do this:

eval echo \$${baz}contents

;-)




Cosmo

Re: Build a variable name from another variable?

[Omen Wild]

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Quoting Philippe Troin <phil@fifi.org> on Fri, Jan 23 15:19:
>
> % t="${baz}contents"   
> % echo ${${(P)t}}
> bar contents
> 
> Works...
> i could not manage to do it without an intermediate variable.

Ah, this will probably work for me.

Quoting Cosmo <cosmo@uk.ibm.com> on Fri, Jan 23 23:47:
>
> Back in the old days, before these fancy complicated shells, I'd just do 
> this:

I simplified a bit for the example, I'm actually trying to do stuff
much more complicated than just a echo...

Thanks,
   Omen

-- 
Where do forest rangers go to "get away from it all"?

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Re: Build a variable name from another variable?

[Bart Schaefer]

On Jan 23,  7:51pm, Omen Wild wrote:
} 
} Quoting Philippe Troin <phil@fifi.org> on Fri, Jan 23 15:19:
} >
} > % t="${baz}contents"   
} > % echo ${${(P)t}}
} > bar contents
} > 
} > Works...
} > i could not manage to do it without an intermediate variable.
} 
} Ah, this will probably work for me.

Here it is without the intermediate variable:

	${(P)${:-${baz}contents}}