Re: Variables as variables

[David Kastrup]

"Phil Holmes" <address@hidden> writes:

> ----- Original Message ----- 
> From: "David Kastrup" <address@hidden>
> To: "Johan Vromans" <address@hidden>
> Cc: <address@hidden>
> Sent: Monday, January 20, 2014 3:23 PM
> Subject: Re: Variables as variables
>
>
>
>> That's not "like a real variable as known from other programming
>> language".  If I write
>>
>> aaa = 3
>> bbb = aaa + 1
>> print ( bbb )
>> aaa = 5
>> print ( bbb )
>>
>> I know of no programming language which will output 6 the second time
>> round.  You are not thinking of a variable, but of a parametric
>> procedure.
>
> IIRC metafont does something of this sort.
mf
This is METAFONT, Version 2.718281 (TeX Live 2013/Debian)
**\relax

*aaa := 3;
bbb = aaa + 1;
show bbb;

*
*>> 4
*aaa := 5;
show bbb;

*>> 4
*

It takes care when reassigning values to a variable to _first_ make the
existing expressions independent from the respective variable.

-- 
David Kastrup