Bdtjtk

In C, you can assign two variables in one line with

b = a = sqrt(10);

In Delphi

b := a := Sqrt(10);

is not allowed.

With IfThen, there is an "alternative" for the ternary operator ?: as discussed in Delphi - Equivalent to C#'s ternary operator? In summary, IfThen doesn't seem absolutely necessary.

So maybe there is also something like this:

function AssignAndReturn(var LHS: Integer; RHS: Integer): Integer;

begin

  LHS := RHS;

  Result := RHS;

end;



(...)



var

  a, b: Integer;

begin

  b := AssignAndReturn(a, Round(Sqrt(10)));

I'm not trying to "make everything look like C". I just noticed, that sometimes it would be nice to "reuse" the right hand side of an assignment in the same line again. (See Lazarus/Free Pascal: How to improve coding style (to avoid using endless loop) of a while loop whose boolean expression is reassigned every pass for example.)

The short answer is:

No. What you want is not possible. And arguably would be of little if any benefit in Delphi.

First, let's discuss a more practical example. To be frank, a = b = f(x); is a rather poor example.

• It's rare that you arbitrarily want the same value assigned to 2 variables.


• Order of operation above has to break the left to right convention otherwise it would first resolve a = b then ? = f(x).


• So there's little justification to favour that over b = f(x); a = b;.


• Basically it's good for byte count (code golf) not readability.

So instead, let's consider the following, more practical scenario:

//Option 1

if ((b = f(x)) > 42)

  //use b

There's no Delphi equivalent to the above, but it's at least as readable/maintainable to write:

//Option 2

b := f(x);

if (b > 42) then

  //use b

There is another option to consider; especially if Option 1 is sitting in the middle of a larger function. Remember small functions are more maintainable and easier for a compiler to optimise. So consider:

//Option 3

...

ProcessRule42(f(x));

...

//Where Rule42 is is implemented as:

procedure ProcessRule42(b: Integer);

begin

  if (b > 42) then

    //use b

end;

Delphi doesn't really seem to be suffering due to not being able to write: if (b := f(x)) > 42 then //use b.

Is there any real benefit to Option 1?

If the Option 2 is at least as good, why would one ever bother with Option 1. The benefit is seen when you consider scoping rules.

//b does not exist

if ((var b = f(x)) > 42) {

  //use b

}

//b does not exist 



// Using the Delphi approach, this becomes:

//b does not exist

var b = f(x);

if (b > 42) {

  //use b

}

//b still exists

Delphi simply does not have the same scoping concerns. Delphi variables are all declared at the beginning of the method, and available for the whole method.

Conclusion

This brings us back to what others have been trying to explain. Delphi is a different language with slightly different approaches to some problems. While I applaud you for examining other options and considering what concepts can be borrowed from other languages: be careful of trying to force-fit some concepts where they don't belong.

If you break too many Delphi paradigms, your code may become unnecessarily difficult for Delphi programmers to maintain.

An assignment statement is not an expression. It does not, and will never, yield a value. The only way to assign to multiple variables in one statement is via a function.

Based on this question and your previous question I would say that you are mistaken in trying to fight against the language. Code into the language you are using. In C you might write

b = a = sqrt(10);

But in Pascal the language wants you to write it like this

a := sqrt(10);

b := a;

Do it this way. Don't create obscure functions just so that you can cram it all onto a single line. The two lines above could not be clearer to read. Stop trying to force other languages into Pascal. They don't fit.