[pmwiki-users] Can't use {(substr )} with the {(calc )} recipe

[Petko Yotov]

James DeVain writes:
> Hi, everyone. I'm using the "{(calc)}" recipe at  
> Cookbook/MarkupExpressionSamples. I'm
> trying to do this:
>
> (:gen:4708003830:)
> {(calc '(substr {$:gen} 0 -8) + 3')}
>
> which should return 50, but I just get "input error!". I've tried it a bunch  
> of different
> ways, but nothing works so far. Might be worth mentioning that if I use the  
> "{(math)}"
> recipe (from the same page), as in:
>
> {(math (substr {*$:gen} 0 -8) + 3)}

Remove the single quotes. To nest markup expressions use

  {(func1 (func2 12 6 (func3 5)) )}

If you use quotes, the stuff in quotes is not searched for nested markup  
expressions.

OTOH if you do arithmetic calculations, you may have to use parentheses, and  
parentheses indicate sub-expressions. Two ways to use arithmetic parentheses  
without quotes and without the markup expressions engine to break:

  {(calc 25 + ( {$:stuff}-0) )} use a space after the ( parenthese
  {(calc 25 + (calc {$:stuff}-0) )} use an actual sub-expression

Petko