typesetting parameters

typesetting parameters

[lists]

Hi list,
	I'm having difficulty understanding why one would define a parameter 
with typeset before using it using.  For example:

integer count=1
until something; do
    something else
    something else
    something else
    (( count++ ))
done

I could just do

count=1
until something; do
    something else
    something else
    something else
    (( count++ ))
done

and get the same results, right?  Similarly,  if I define a scalar 
variable or non-associative array with 'var=foo' and 'array=(one two 
three)', is that different from doing 'typeset var=foo' and 'typeset -a 
array; array=(one two three)'?  Any explanations, online guides, or FMs 
to R would be much appreciated.

Re: typesetting parameters

[Bart Schaefer]

On Sun, 13 Jun 2004, lists wrote:

> 	I'm having difficulty understanding why one would define a parameter 
> with typeset before using it.

One probably wouldn't, when interactively typing commands, unless one
wanted to use the special attributes such as padding, alignment, other
integer bases, or floating-point precision.

The primary time/place and reason to use typeset is when defining shell
functions, to create variables that are local to the function scope. When
you use "local" that's really an alias for typeset.

Re: typesetting parameters

[Vincent Stemen]

On Sun, Jun 13, 2004 at 09:58:57PM -0700, Bart Schaefer wrote:
> On Sun, 13 Jun 2004, lists wrote:
> 
> > 	I'm having difficulty understanding why one would define a parameter 
> > with typeset before using it.
> 
> One probably wouldn't, when interactively typing commands, unless one
> wanted to use the special attributes such as padding, alignment, other
> integer bases, or floating-point precision.
> 
> The primary time/place and reason to use typeset is when defining shell
> functions, to create variables that are local to the function scope. When
> you use "local" that's really an alias for typeset.

Not only that, even outside of functions, some expressions such as

    variable+=$value

will not always behave as intended if the variable is not typeset.  If
it is typeset as an array for example, you can depend on it appending
"$value" to the list.  Otherwise it might try to add it as an integer
or append it as a string, depending on it's value.

Regards,
Vincent

-- 
Vincent Stemen
Avoid the VeriSign/Network Solutions domain registration trap!
Read how Network Solutions (NSI) was involved in stealing our domain name.
http://www.InetAddresses.net

Re: typesetting parameters

[lists]

What a friendly and helpful list this is.  Thanks Vincent and Bart!


On Jun 14, 2004, at 1:24 PM, Vincent Stemen wrote:

> On Sun, Jun 13, 2004 at 09:58:57PM -0700, Bart Schaefer wrote:
>> On Sun, 13 Jun 2004, lists wrote:
>>
>>> 	I'm having difficulty understanding why one would define a parameter
>>> with typeset before using it.
>>
>> One probably wouldn't, when interactively typing commands, unless one
>> wanted to use the special attributes such as padding, alignment, other
>> integer bases, or floating-point precision.
>>
>> The primary time/place and reason to use typeset is when defining 
>> shell
>> functions, to create variables that are local to the function scope. 
>> When
>> you use "local" that's really an alias for typeset.
>
> Not only that, even outside of functions, some expressions such as
>
>     variable+=$value
>
> will not always behave as intended if the variable is not typeset.  If
> it is typeset as an array for example, you can depend on it appending
> "$value" to the list.  Otherwise it might try to add it as an integer
> or append it as a string, depending on it's value.
>
> Regards,
> Vincent
>
> -- 
> Vincent Stemen
> Avoid the VeriSign/Network Solutions domain registration trap!
> Read how Network Solutions (NSI) was involved in stealing our domain 
> name.
> http://www.InetAddresses.net
>