Need some way to debug brew templates

[vlsi]

Current brew errors are hard to impossible to debug.

It might throw Error: Error (duplicate 'row.names' are not allowed) in your BRCODEs: and you are alone with the error.

The best I figured out is a binary search over the template source (just exclude half of the text) to identify the bad statement.

options(error=traceback), error=browser, error=recover do not help (I did not manage to figure out the failing line of code).

Nicer error reporting would be very handy.

[vlsi]

Hm. Executing BRCODEs one-by-one allows to identify bad line, however proper backtrace would be still good.

[daroczig]

I would suggest using BRCATCODE (<%= ... %>) over BRCODE tags that would report the error and its message at the exact place in the report. The is no sense in using BRCODE in most of the cases -- just for loops and conditional parts of the document. What you think about this?

[vlsi]

Avoiding <% %> is a nice idea, however it still misses to trace error to the source location (line numbers, or/and local variables)

[daroczig]

That's right. Unfortunately I have no further ideas how could I improve error reporting, but would love to hear your suggestions.

What also helps me to debug my reports is to check the structure of the returned object that also show the source code (command) beside the captured messages:

> str(Pandoc.brew(text = '<%=error%>'))
 **ERROR**^[object 'error' not found] 
List of 2
 $ :List of 2
  ..$ type   : chr "block"
  ..$ robject:List of 6
  .. ..$ src   : chr "error"
  .. ..$ result: NULL
  .. ..$ output: chr " **ERROR**^[object 'error' not found]"
  .. ..$ type  : chr "error"
  .. ..$ msg   :List of 3
  .. .. ..$ messages: NULL
  .. .. ..$ warnings: NULL
  .. .. ..$ errors  : chr "object 'error' not found"
  .. ..$ stdout: NULL
  .. ..- attr(*, "class")= chr "evals"
 $ :List of 4
  ..$ type  : chr "text"
  ..$ text  :List of 2
  .. ..$ raw : chr "\n"
  .. ..$ eval: chr "\n"
  ..$ chunks:List of 2
  .. ..$ raw : NULL
  .. ..$ eval: NULL
  ..$ msg   :List of 3
  .. ..$ messages: NULL
  .. ..$ warnings: NULL
  .. ..$ errors  : NULL

[daroczig]

Please let me know if you would have any ideas to improve error reporting.