What is that $(...) construct?

[ChristofSchwarz]

If you are Qlik "scripter" or building advanced Qlik Dashboards ( Qlik Sense, QlikView), then you will come across the $(...) and $(=...) constructs within measure formulas or within the Qlik load script.

Construct	Scope	Explained
$(...)	Load Script	example $(var1) injects the content of the variable v1 betweem the $( and ).
$(...)	Measure Formula	example $(var1) executes the variable like code and inserts the result between the $( and ).
$(=...)	Measure Formula	example $(=Year(Today())) injects the result of the ad-hoc formula =Year(Today()) into the place between $( and )

$(...)

So far so good. Some believe, you always have to use the syntax $(...) together with variables, but that is not right. Assume you set the variable v1:

LET v1 = 'Qlik'; 

and you want to use the variable in a color formula:

If('$(v1)' = 'Qlik', 'green', 'gray') // is identical to
If(v1 = 'Qlik', 'green', 'gray')

but the 2nd syntax is simpler. Only in Load Script, when you use variables within a LOAD statement, all names you use there are considered field names, not variables; there you'd have to use the $(...) syntax to resolve the variable.

However it is a practice to use variables also to carry formulas, say

SET expr1 = Sum(Sales); 

Now, if you create a measure in a chart and put =expr1 what you will get is the static text 'Sum(Sales)' which is the context of the variable, and not the calculation result. Here you must use =$(expr1) to get the content Sum(Sales) interpreted for the respective measure.

$(=...)

Shifting gears and make a bit more complex example for your load script:

SET smodifier = Segment={"mid-market"};
SET expr2 = Sum({< $(smodifier) >} Sales);
SET expr3 = Sum({< $(smodifier), SalesYear={$(=Year(Today()))} >} Sales);

Obviously, in expr3 you would like to dynamically filter SalesYear to the current year using a set-analysis syntax. But what will happen?

The expr2 will work. According to what I wrote earlier, the expr2 will inject the smodifier  variable content within expr2 and it will contain Sum({< Segment={"mid-market"} >} Sales);

Note, that the text $(smodifier) is no more part of expr2, because the replacement of the $(...) happens already in script run time. 

expr3, however, will not work, because the $(= ...) will be blank. Remember, $(=...) doesn't work within script. The variable expr3 will, unintendedly, contain an empty text within the SalesYear set-modifier:

Sum({< Segment={"mid-market"} , SalesYear={} >} Sales);

In order to set a variable in load script to carry the $(=...) construct you have to use an artificial syntax, that separates the $ from the (, such as $:(...)  -- see the colon sign inbetween!

Same goes for $(...) construct, which you intend not to resolve at script execution, but in the frontend. 

Finally, replace the $:( to $( by calling the following SUB routine (copy/paste it into the beginning of your script from here https://raw.githubusercontent.com/ChristofSchwarz/QlikScripts/master/FixVariables.txt )

SET var1 = 'US';
SET smodifier = Segment={"mid-market"};
SET expr3 = Sum({< $(smodifier), SalesYear={$:(=Year(Today()))} >} Sales);
SET expr4 = Sum({< $(smodifier), Cntry={"$:(var1)"} >} Sales);
CALL FixVariables('expr3, expr4');

After this what you will get in the variables is:

• expr3: Sum({< Segment={"mid-market"}, SalesYear={$(=Year(Today()))} >} Sales);
• expr4: Sum({< Segment={"mid-market"}, Cntry={"$(var1)"} >} Sales);

Now expr3 and expr 4 can be used in a measure in the Sheet objects like

=$(expr3)

Note, that Qlik can resolve nested constructs, for example there is a $(=...) within $(expr3) and a $(...) within $(expr4) which will be resolved.

Hope this helps understand the difference between $(...) and $(=...) and when used in script as opposed to measure formulas.