Requesting the addition of a [PRIVATE] keyword to protect user-defined package-scope PROC DS2 variables from direct access from outside an instance of the package.
Private variables and methods are a common feature of object orientated programming. See Why do we need private variables?.
Suppose this PROC DS2:
proc ds2 ;
/* Create a piggy bank that applies business rules */
package piggyBank / overwrite=YES;
dcl double balance limit;
method piggyBank();
limit=1000;
balance=0;
end;
method add_amount(double iAmount);
if sum(iAmount, balance) > limit then
put 'ERROR: Deposit exceedes limit!';
else
balance=sum(iAmount, balance);
end;
method print_balance();
put balance=;
end;
endpackage;
/* Create and add bogus amounts to the bank */
data _null_;
method run();
dcl package piggyBank myBank();
myBank.print_balance();
/* No problem to add 45 to the balance */
myBank.add_amount(45);
/* This will print an error message */
myBank.add_amount(5000);
/* Bypass the business rules and directly set the balance.
I propose a [PRIVATE] keyword that would prevent
`balance` from being directly accessible.
*/
myBank.balance=100000;
end;
enddata;
run;
quit;
It is ashame that `piggyBank.balance` is directly accessible. You can bypass the business rules and directly edit the balance! My idea is for a `private` keyword that can be used to prevent direct access, something like:
package piggyBank / overwrite=YES;
dcl double [PRIVATE] balance;
/* ... code omitted for brevity ... */
/* SAS won't compile this and will print an error */
myBank.balance = 10000;
Apologies if there's a way that I'm missing to do this. Thanks.
