[Oberon] Re (2): Porting S3 / V4 Oberon

[August Karlstrom]

On 2021-01-03 16:08, peter at easthope.ca wrote:
> What  about tolerating RETURN and EXIT but not LOOP?

If we exit prematurely from a WHILE, REPEAT or FOR statement our code is 
potentially lying. If we read

	WHILE someCondition DO
		...
	END

we should be able to conclude that the guarded statements are repeated 
as long as someCondition is true, and that someCondition is false when 
(or if) the loop has finished. That's the beauty of a purely structured 
language such as (the latest) Oberon; there are no partially executed 
statement sequences (unless the ASSERT statement is being used). Compare 
this to

	WHILE someCondition DO
		...
		IF someOtherCondition THEN
			EXIT (*ugh!*)
		END;
		...
		IF someThirdCondition THEN
			RETURN (*ugh!*)
		END;
		...
	END
	(*~someCondition???*)


-- August