Re: [babel] passing strings in

["Thomas S. Dye" <tsd@tsdye.com>]

On Mar 25, 2010, at 6:49 AM, Dan Davison wrote:

> "Eric Schulte" <schulte.eric@gmail.com> writes:
>
>> Hi Maurizio,
>>
>> The ip addresses in your table are being interpreted as source/ 
>> reference
>> names which org-babel is trying to resolve.  In order to  
>> differentiate
>> between strings and reference names, we either must surround all  
>> strings
>> in double quotes (as below) or we must end all references with "()"  
>> and
>> disallow any strings which end in "()".
>
> Hi Eric,
>
> Thanks for the much better answer. I think my vote goes for your  
> second
> option. In other words, :var x=blockname passes the string  
> "blockname",
> whereas :var x=blockname() passes the result of evaluating a block
> called "blockname".
>
> One argument for this is that in order to pass arguments to a block
> being evaluated as a reference, users are already obliged to use the
> parenthetic function call syntax:
>
> :var x=blockname(arg1=val1)
>
> so demanding the parentheses in the absence of arguments is natural  
> (and
> perhaps even serves to remind users of the possibility of passing
> arguments).
>
> Also I think that users will probably pass strings more often than  
> they
> will pass the results of block reference evaluations, so
> interpreting :var=blockname as a string literal may also be  
> justified by
> Least Surprise for naive users (e.g. apparently me...).
>
> Dan
>
>
>
>
>> Currently we are taking the
>> former approach, which means your table will require the following to
>> work...
>>
>> #+TBLNAME: system-host-ping :var host=system-hosts
>> | name   | ip               |           ping |
>> |--------+------------------+----------------|
>> | host 1 | "192.168.10.200" | 192.168.10.200 |
>> | host 2 | "192.168.10.24"  |  192.168.10.24 |
>> | host 3 | "192.168.42.24"  |  192.168.42.24 |
>> #+TBLFM: $3='(sbe system-ping (ip $2))'
>>
>> #+source: system-ping
>> #+begin_src sh :var ip=0
>> # This is what I eventually want
>> #ping -w 10 -c 1 -q $ip >/dev/null 2>&1
>> #echo $?
>>
>> # Testing
>> echo $ip
>> #+end_src
>>
>> I'd be open to discussion on this issue.  I suppose if reference
>> resolution fails we could try using the name as a string literal, but
>> that could lead to debugging nightmares...
>>
>> Cheers -- Eric
>>
>> Maurizio Vitale
>> <mav@cuma.i-did-not-set--mail-host-address--so-tickle-me> writes:
>>
>>> In the table/block pair below, I'm trying to pass an IP number to  
>>> some
>>> shell code. It seems like in the table formula I can only have
>>> numbers. Is that right?
>>>
>>> #+TBLNAME: system-host-ping :var host=system-hosts
>>> | name      |             ip | ping   |
>>> |-----------+----------------+--------|
>>> | host 1    | 192.168.10.200 | #ERROR |
>>> | host 2    |  192.168.10.24 | #ERROR |
>>> | host 3    |  192.168.42.24 | #ERROR |
>>> #+TBLFM: $3='(sbe system-ping (ip $2))'
>>>
>>> #+source: system-ping
>>> #+begin_src sh
>>> # This is what I eventually want
>>> #ping -w 10 -c 1 -q $ip >/dev/null 2>&1
>>> #echo $?
>>>
>>> # Testing
>>> echo $ip
>>> #+end_src
>>>
>>> Any way to pass arbitrary strings?
>>>
>>> Thanks a lot,
>>>
>>>       Maurizio
>>>
>>>
>>>
>>>
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>>
>>
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>
>
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Aloha all,

Would it be useful to interpret arguments like this?

arg -> interpretation
-------------------
"string" -> string
"reference()" -> string
reference -> string
reference() - reference

If reference resolution fails then an error could be raised  
unambiguously.

All the best,
Tom