check.ErgmTerm() now only allows a NULL argument if 1) it's listed in…

… the vartypes explicitly or 2) it's optional and the default is NULL; new constant, ERGM_VATTR_SPEC_NULL has been defined, equivalent to ERGM_VATTR_SPEC plus NULL.

fixes #349

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: ergm
-Version: 4.0-6570
+Version: 4.0-6572
 Date: 2021-07-13
 Title: Fit, Simulate and Diagnose Exponential-Family Models for Networks
 Authors@R: c(

NAMESPACE

@@ -160,6 +160,7 @@ export(ERGM_STATE_C_CHANGED)
 export(ERGM_STATE_RECONCILED)
 export(ERGM_STATE_R_CHANGED)
 export(ERGM_VATTR_SPEC)
+export(ERGM_VATTR_SPEC_NULL)
 export(LARGEST)
 export(SMALLEST)
 export(approx.hotelling.diff.test)

R/check.ErgmTerm.R

@@ -41,7 +41,7 @@ ergm_Init_warn_once <- once(ergm_Init_warn)
 #' @param varnames the vector of names of the possible arguments for
 #'   term X; default=NULL
 #' @param vartypes the vector of types of the possible arguments for
-#'   term X, separated by commas; an empty string (`""`) or `NA` disables the check for that argument; default=NULL
+#'   term X, separated by commas; an empty string (`""`) or `NA` disables the check for that argument, and also see Details; default=NULL
 #' @param defaultvalues the list of default values for the possible
 #'   arguments of term X; default=list()
 #' @param required the logical vector of whether each possible
@@ -58,6 +58,10 @@ ergm_Init_warn_once <- once(ergm_Init_warn)
 #'   containing a named logical vector indicating whether a particular
 #'   argument had been set to its default.
 #'
+#' @details As a convenience, if an argument is optional *and* its
+#'   default is `NULL`, then `NULL` is assumed to be an acceptable
+#'   argument type as well.
+#'
 #' @import network
 #' @export check.ErgmTerm
 check.ErgmTerm <- function(nw, arglist, directed=NULL, bipartite=NULL, nonnegative=FALSE,
@@ -127,8 +131,9 @@ check.ErgmTerm <- function(nw, arglist, directed=NULL, bipartite=NULL, nonnegati
     val <- out[[m]]
 
     # Check type
-    if(!is.na(vartypes[m]) && nchar(vartypes[m])
-       && all(sapply(strsplit(vartypes[m],",",fixed=TRUE)[[1]], function(vartype) !is.null(val) && !is(val, vartype))))
+    if(!is.na(vartypes[m]) && nchar(vartypes[m]) &&
+       !(is.null(val) && !required[[m]] && is.null(defaultvalues[[m]])) &&
+       all(sapply(strsplit(vartypes[m],",",fixed=TRUE)[[1]], function(vartype) !is(val, vartype))))
       ergm_Init_abort(sQuote(name), " argument is not of any of the expected (", vartypes[m], ") types.")
 
     # Check deprecation (but only if passed explicitly)

R/get.node.attr.R

@@ -644,6 +644,10 @@ ergm_attr_levels.formula <- function(object, attr, nw, levels=sort(unique(attr))
 #' @export
 ERGM_VATTR_SPEC <- "function,formula,character,AsIs"
 
+#' @rdname nodal_attributes-API
+#' @export
+ERGM_VATTR_SPEC_NULL <- "function,formula,character,AsIs,NULL"
+
 #' @rdname nodal_attributes-API
 #' @export
 ERGM_LEVELS_SPEC <- "function,formula,character,numeric,logical,AsIs,NULL,matrix"