( in preprocessor

[NotNull]

addcol:a a:=[repeat:"(",3]

=> ""

addcol:a a:=[repeat:"[",3]

=> ""

addcol:a a:=[repeat:")",3]

=> ")))"

addcol:a a:=[repeat:"]",3]

=> ")))"

What is going on here? (and how to work around it?)

Other non-alphanumeric characters give unexpected results too.

[Phlashman]

Try
addcol:a a:=[repeat:char(40),3]

where char() is the character function and 40 is the ASCII dec code for the "(" character

[void]

[repeat:"(",3]

is the term processor.
The term processor is applied before formulas

[repeat:"(",3] => (((

Which is then evaluated as a formula.
Formulas will treat unhandled text as literal.
( is handled as parenthesis.
Although, there's no terminating )
I want to at some stage return an #error: value.
For now, formulas are not strict.

Please try the following instead:

addcol:a a:=REPEAT("(",3)

The formula REPEAT() function returns a string.

[NotNull]

addcol:a a:=[repeat:char(40),3]

Good idea! Tested and works fine. Thanks!

[..] Which is then evaluated as a formula.

Aha, the fog is lifting a bit ..
Testing: addcol:B B:=((( gives an empty colum too.
And indeed: a:=&quot:[repeat:"(",3]&quot: gives the expected result.

Please try the following instead:
addcol:a a:=REPEAT("(",3)

Will try, but for what I want to do, the term processor needs to build some formulas *before* they are executed.

[void]

addcol:a a:=[repeat:char(40),3]

expands to:

char(40)char(40)char(40)

Formulas evaluate this as:

(((