Selection set question

[Kenneth Brody]

Quoting Walter Vaughan (Wed, 14 Nov 2007 15:23:25 -0500):

> Nancy Palmquist wrote:
>
>> -rx   - @px
>> -ry   - @py
>> -rz   - @pz
>>
>> (You have 4 ways to pass data to the command directly).
>
> FWIW you can have many more than 4. Even before we had the extra   
> "-r" commands,
> I'd been sending delimited type data over that channel and parsing   
> the @PM field to pass multiple fields of data.
>
> ... -r "1234AACA1234GGGG3456"
>
> a=mid(@pm,"1","4");b=mid(@pm,"5","4";c=mid(@pm,"9","4");d=mid(@pm,"13","8")
>
> In fact I always wondered what the deal was in adding only three   
> more. I never did see the limitation that was solved by creating
> @px, y and z????

(BTW, you both forgot about -rw/@PW.)

It was for ease of coding, rather than getting around a "limitation".
Sure, in your case, you have fixed-length 4-character values, which
are easy to grab with mid().  But what about cases where you would
have to pass a delimited value and parse it, such as something like:

    -r "1:New York:Smith:Bob"

Yes, the command line is more compact than:

    -r "1" -rx "New York" -ry "Smith" -rz "Bob"

But the code needed to parse it is a lot more than simply looking at
@PM/@PX/@PY/@PZ.

-- 
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