Multiple target assignment (was: Re: Adoption of new RPG techniques)

[Hans Boldt <boldt@xxxxxxxxxx>]

Lurton Keel wrote:
> I haven't been following the /free discussion much but is there or are there
> plans to adopt multiple assignments in one /free statement?
>
>   a=b=c=d=e=f=g=h=*zero;
>   
>   k=l=m=n=*blanks; 

No. The statements you list actually compile today, but it doesn't 
mean multiple assignment. The left-most '=' is the assignment 
operator. The rest are the equality comparison operator.

Of course, that does not preclude the possibility of multiple target 
assignment in the future. It just means that a different syntax 
would have to be used. For example, something like, say, "a,b,c=0;" 
would not cause any existing code to work differently.

As an aside, many programming languages differentiate between the 
two, with '=' and '==' operators in many commonly used languages 
(like C, Python, Java, Perl, etc.), or ':=' and '=' in others (like 
Pascal, Modula2, ADA, etc.). RPG IV syntax was influenced by the 
PL/I family of languages, which uses '=' for both operations.

Having distinct operators allows assignment to be treated as an 
expression in some languages. But in those particular languages, the 
practice of coding assignments as expressions is generally 
discouraged since it is a common source of bugs. On the other hand, 
in those languages where assignment cannot be coded as an 
expression, having two operators emphasizes that assignment and 
comparison are two completely different operations.

Cheers! Hans