fundamental programming questions: semicolon and assignment

[daveatkins]

Sorry to ask a dumb questions or two but:

1) is a semicolon recommended to terminate every line? I have found cases where code seems to work without it but lots of inconsistency. The lack of strictness promotes laziness in coding of which I am guilty but I would like to know if there is some purpose or rule.

2) is it best practice to always assign variables with LET x = whatever? I am familiar with the confusing LET vs SET distinction and how that can be a "feature" but it seems that one can simply say x = 1 and this works as fine as LET x = 1. What is the default behavior; i.e. I say thisDate = today(); or LET thisDay=today()?  

[rwunderlich · Accepted solution]

1) Script regular statements must be terminated by a semicolon.  Script control statements, such as CALL,  may be terminated by either a semicolon or end of line.  Also the contents of a control statement must be contained within one line. 

So semicolons are only optional in control statements, which is a very small number (or zero) of lines in a typical  script. I'm not sure why control statements were designed with a different restriction -- perhaps someone else has an explanation.   It was years before I even knew that you could use a semicolon on a control statement.  I teach beginners to use semicolons on control statements but point out that they are optional because they are likely to encounter script without them.

2) "thisDate = today()" is the same as "Let thisDate = today()".  In my opinion it's a best practice to always include the "Let" so others don't have to wonder what the behavior is.  Just my opinion.

-Rob
http://www.easyqlik.com
http://masterssummit.com
http://qlikviewcookbook.com

[daveatkins]

thanks; my main questions were around control statements while/for loops, etc. which I had seen with and without semicolons. I was thinking that the control statement was essentially starting a kind of unpunctuated block...but if the semi is recommended then stuff like this is valid and recommended?:

FOR i = 1 to 10;

LET value = PEEK($(tablename),$(i));

LET resultStr = resultStr & ', ' & value & '<BR \>';

NEXT;

The whole let thing also seems weird but this is part of the mystery of qlik coding.

[rwunderlich]

The semicolons on control statements do look a bit silly when you understand the complete picture.  My motivation for teaching beginners to include them is twofold:

1) Beginners are frequently confused between "control statements" and "regular statements".  So I tell them for now,  just code the semicolon and will spend our class time on something more useful.  😉

2) I'm hoping that if we all use semicolons, I can convince Qlik to allow control statements to span lines so I can write statements like:

CALL MySub (
  parm1, 
  parm2
);

So not really a recommendation. More like if I have to fall off the fence one way or another, that's why I fall the way I do. 

-Rob