OpenEuphoria

Re: Coming From QBasic

• Posted by "Lynn Kilroy" <leks_transportation at hotmail.com> Jan 17, 2006
• 543 views

I see nothing wrong with passing an argument to a subroutine/procedure {to 
me, these are really the same thing}, and allowing that subroutine to alter 
it.  In QBasic, if I said:

>DECLARE SUB Inke (a AS STRING)
>
>SUB Inkey (a AS STRING)
>a = INKEY$
>END SUB

what I'm saying is Inkey requires the argument 'a,' which passes data to and 
can also extract data from the subroutine.   If I included a local variable 
in that subroutine:

>DECLARE SUB Inke (a AS STRING)
>
>SUB Inkey (a AS STRING)
>
>DIM Variable AS DOUBLE
>
>Variable = RND
>
>a = INKEY$
>
>END SUB

then Variable is only remembered by Inkey. but is never seen by the rest of 
the program.  In this case, it is a useless excercise becuase nothing is 
done with it.  As you say, local versus global.

Also, in both cases above, the line

>SUB Inkey (a AS STRING)

means you *MUST* pass it an argument.  That argument can be either a 
variable pointer or a constant hard coded as an argument.  In the case of 
Inkey, you could pass it arguments the following way, and they would all 
work.

>DIM KeyPress AS STRING
>
>Inkey KeyPress

-Or-

>Inkey X$

-Or-

>Inkey " "

The first two are variables.  I never use the signed variables.  Poor form, 
and rather tasteless to me, anymore, so the middle one is out.  But I use 
variations of the top and bottom lines quite frequently, although in the 
case of Inkey, calling Inkey with " " as the argument {a hard coded 
constant} rather defeats the purpose.

In Euphoria, the sub would look different.  I'm going to use your code and 
take a whack at it.

>Procedure Inkey(Integer Key)
>     Key = get_key()
>End Procedure
>
>Integer Key
>
>Inkey(Key)

Would this work?  If not this precisely, then how would it be coded, 
precisely?  The difference isn't so much that I use a global variable for it 
{Blech!} but that I pass a variable to it, and the variable is altered by 
the Subroutine/Procedure and then passed back to the main program {if the 
main program had a variable pointer in the first place}.

Love & Friendship & Blessed Be!
Lynn Erika Kilroy

>From: "D. Newhall" <guest at RapidEuphoria.com>
>Reply-To: EUforum at topica.com
>To: EUforum at topica.com
>Subject: Re: Coming From QBasic
>Date: Mon, 16 Jan 2006 09:16:46 -0800
>
>
>posted by: D. Newhall <derek_newhall at yahoo.com>
>
>Lynn Kilroy wrote:
> >
> > Does the Global function thingy have to be included in the main body of 
>the=
> > code, even if the function is in an included file?  And how about the
> > subroutines?  How do I call them?
> >
> > Love & Friendship & Blessed Be!
> > Lynn Erika Kilroy
>(snip)
>
>As you've probably seen Euphoria doesn't have BASIC/COBOL style 
>subroutines. However, you can kind of replicate this with procedures using 
>global variables.
>
>integer key
>
>procedure inkey()
>     key = get_key()
>end procedure
>
>inkey()
>
>
>When you declare something as global in an include file that means that 
>when you include it everything declared as global becomes available in the 
>main file. For example:
>
>-- Inside some include file
>constant BLAH = "stuff"
>
>global integer foo
>
>global function bar()
>     ...
>end function
>
>procedure baz()
>     ...
>end procedure
>
>
>When this file is included foo and bar can be used in the code whereas baz 
>and blah can not.
>
>
>The Euphoria Standard Library project :
>     http://esl.sourceforge.net/
>The Euphoria Standard Library mailing list :
>     https://lists.sourceforge.net/lists/listinfo/esl-discussion
>
>
>
>