Forcing a package's function to use user-provided function

Question

I\'m running into a problem with the MNP package which I\'ve traced to an unfortunate call to deparse (whose maximum width is limited to 500 charac

Answer 1

This is how packages with namespaces search for functions, as described in Section 1.6, Package Namespaces of Writing R Extensions

Namespaces are sealed once they are loaded. Sealing means that imports and exports cannot be changed and that internal variable bindings cannot be changed. Sealing allows a simpler implementation strategy for the namespace mechanism. Sealing also allows code analysis and compilation tools to accurately identify the definition corresponding to a global variable reference in a function body.

The namespace controls the search strategy for variables used by functions in the package. If not found locally, R searches the package namespace first, then the imports, then the base namespace and then the normal search path.

Answer 2

The functions fixInNamespace and assignInNamespace are provided to allow editing of existing functions. You could try ... but I will not since mucking with deparse looks too dangerous:

 assignInNamespace("deparse", 
                  function (expr, width.cutoff = 60L, backtick = mode(expr) %in% 
               c("call", "expression", "(", "function"), control = c("keepInteger", 
               "showAttributes", "keepNA"), nlines = -1L)  {
    ret <- .Internal(deparse(expr, width.cutoff, backtick, .deparseOpts(control), nlines))
    paste0(ret,collapse="")
                         }   , "base")

There is an indication on the help page that the use of such functions has restrictions and I would not be surprised that such core function might have additional layers of protection. Since it works via side-effect, you should not need to assign the result.