[External] Get list of active calling handlers?

The SO post https://stackoverflow.com/q/77943180 tried to call 
globalCallingHandlers() from a function, and it failed with the error message 
"should not be called with handlers on the stack".  A much simpler 
illustration of the same error comes from this line:

 try(globalCallingHandlers(warning = function(e) e))

The problem here is that try() sets an error handler, and 
globalCallingHandlers() sees it and aborts.

If I call globalCallingHandlers() with no arguments, I get a list of 
currently active global handlers.  Is there also a way to get a list of 
active handlers, including non-global ones (like the one try() added in the 
line above)?
There is not. The internal stack is not safe to allow to escape to the
R level.  It would be possible to write a reflection function to
provide some information, but it would be a fair bit of work to design
and I don't think would be of enough value to justify that.

The original SO question would be better addressed to
Posit/RStudio. Someone with enough motivation might also be able to
figure out an answer by looking at the source code at
https://github.com/rstudio/rstudio.

Best,

luke
Duncan Murdoch

______________________________________________
R-devel at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel

Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
    Actuarial Science
241 Schaeffer Hall                  email:   luke-tierney at uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu

[External] Get list of active calling handlers?

Thread (3 messages)