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Re: need ability to tell if array is associative or not - bug?


From: Jason Vas Dias
Subject: Re: need ability to tell if array is associative or not - bug?
Date: Fri, 29 Aug 2014 16:57:46 +0100

Sorry - forget the bit about indirect expansion - the error only
occurs if the array is originally declared not associative :

$ ( function f()  {       local an_array=$1;     local value='1.0';
local ev='['"'"'value'"'"']='"'""$value""'";     eval
${an_array}='('"$ev"')'; }; declare -a my_array; set -x; f my_array )
+ f my_array
+ local an_array=my_array
+ local value=1.0
+ local 'ev=['\''value'\'']='\''1.0'\'''
+ eval 'my_array=(['\''value'\'']='\''1.0'\'')'
++ my_array=(['value']='1.0')
bash: 1.0: syntax error: invalid arithmetic operator (error token is ".0")

$ ( function f()  {       local an_array=$1;     local value='1.0';
local ev='['"'"'value'"'"']='"'""$value""'";     eval
${an_array}='('"$ev"')'; }; declare -A my_array; set -x; f my_array )
+ f my_array
+ local an_array=my_array
+ local value=1.0
+ local 'ev=['\''value'\'']='\''1.0'\'''
+ eval 'my_array=(['\''value'\'']='\''1.0'\'')'
++ my_array=(['value']='1.0')
$
(no error) .

And just evaluating :
$ ( declare -a my_array; my_array=(['value']='1.0') )
gives no error either, but there is no 'value' subscript.



On 8/29/14, Jason Vas Dias <address@hidden> wrote:
> Actually, this appears to be a bit more involved.
> What I was actually trying to work out was
> the bash error that occurs with :
>
> $( function f()
> {
>     local an_array=$1;
>     local value='1.0';
>     local v=value;
>     local ev='['"'"'value'"'"']='"'""${!v}""'";
>     eval ${an_array}='('"$ev"')';
> }
>   declare -a my_array;
>   set -x; f my_array;
> )
> + f my_array
> + local an_array=my_array
> + local value=1.0
> + local v=value
> + local 'ev=['\''value'\'']='\''1.0'\'''
> + eval 'my_array=(['\''value'\'']='\''1.0'\'')'
> ++ my_array=(['value']='1.0')
> bash: 1.0: syntax error: invalid arithmetic operator (error token is ".0")
>
> This error does not happen if the array was originally declared
> associative:
>
> $ ( function f()  {       local an_array=$1;     local value='1.0';
>  local v=value;     local ev='['"'"'value'"'"']='"'""${!v}""'";
> eval ${an_array}='('"$ev"')'; };
> declare -A my_array; set -x; f my_array )
> + f my_array
> + local an_array=my_array
> + local value=1.0
> + local v=value
> + local 'ev=['\''value'\'']='\''1.0'\'''
> + eval 'my_array=(['\''value'\'']='\''1.0'\'')'
> ++ my_array=(['value']='1.0')
>
> Nor does the error happen if indirect expansion is not used:
>
> $ ( function f()  {       local an_array=$1;     local value='1.0';
>      local v=$value;
>      local ev='['"'"'value'"'"']='"'""$v""'";
>      eval ${an_array}='('"$ev"')'; }; declare -A my_array; set -x; f
> my_array )
> + f my_array
> + local an_array=my_array
> + local value=1.0
> + local v=1.0
> + local 'ev=['\''value'\'']='\''1.0'\'''
> + eval 'my_array=(['\''value'\'']='\''1.0'\'')'
> ++ my_array=(['value']='1.0')
> $
>
> So I was wondering if there is any way to determine if an array was
> originally
> declared associative or not.
>
> But it appears that there is a bash bug here that is triggered only if the
> array was originally declared not associative and an indirect expansion
> is involved in setting an array member.
>
> The end result expression being evaluated:
>     ++ my_array=(['value']='1.0')
> should never involve an arithmetic expression,
> and should be valid regardless if the array is
> associative or not .
>
> Any ideas what might be going on here ?
>
> Thanks in advance,
> Jason
>
> On 8/29/14, Jason Vas Dias <address@hidden> wrote:
>> Sorry, mailer sent previous mail before I was ready. Reposting.
>>
>> Good day list -
>>
>> There seems to be no way of testing if an array variable is associative
>> or
>> not ,
>>
>> I have something like:
>>
>>     declare -xr TYPE_ARRAY=0 TYPE_ASSOC=1
>>     function f()
>>     {  declare -n an_array=$1;
>>        local type=$2;
>>        case $type in
>>          $TYPE_ASSOC)
>>               an_array['some_value']=1;
>>               ;;
>>          $TYPE_ARRAY)
>>               an_array[0]=1;
>>        esac
>>    }
>>
>> Now, if I call :
>>    declare -a my_array();  f my_array $TYPE_ASSOC;
>> I'll end up with no 'some_value' subscript in array.
>>
>> It would be great if bash could provide some '-A'  conditional
>> expression operator
>> to test if a variable is an associative array or not .
>> Or perhaps 'declare -A identifier' could return non-zero if
>> 'identifier' was not previously defined as an associative array, as
>> declare -F does for functions ?
>> Or is there some way to test if a variable is an associative array or
>> not?
>>
>> Thanks & Regards,
>> Jason
>>
>>
>> On 8/29/14, Jason Vas Dias <address@hidden> wrote:
>>> Good day list -
>>>
>>> There seems to be no way of testing if an array variable is associative
>>> or
>>> not ,
>>> yet attempting to make associative assigments to a normal array results
>>> in
>>> a
>>> syntax error .
>>>
>>> I have something like:
>>>
>>>     declare -xr TYPE_ARRAY=0 TYPE_ASSOC=1
>>>     function f()
>>>     {  declare -n an_array=$1;
>>>        local type=$2;
>>>        case $type in
>>>          $TYPE_ASSOC)
>>>               an_array['some_value']=1;
>>>
>>>
>>>     }
>>>
>>
>



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