formally documented magic number

DESCRIPTION

@@ -63,6 +63,7 @@ Collate:
     'DataLongitudinal.R'
     'DataSurvival.R'
     'DataJoint.R'
+    'constants.R'
     'StanModule.R'
     'Prior.R'
     'Parameter.R'

R/JointModel.R

@@ -8,6 +8,7 @@
 #' @include LongitudinalModel.R
 #' @include SurvivalModel.R
 #' @include Link.R
+#' @include constants.R
 NULL
 
 
@@ -161,7 +162,8 @@ sampleStanModel.JointModel <- function(object, data, ...) {
     args[["chains"]] <- if ("chains" %in% names(args)) {
         args[["chains"]]
     } else {
-        4
+        # Magic constant from R/constants.R
+        CMDSTAN_DEFAULT_CHAINS
     }
 
     initial_values <- if ("init" %in% names(args)) {

R/constants.R

@@ -0,0 +1,14 @@
+
+
+
+# This file defines any magic numbers or constants used in the package.
+
+# The default number of chains to use when sampling from a Stan model.
+# This is the default set by the `cmdstanr` package however we need to fix it
+# as if they were to change it it would break our code as we create the number
+# of initial values based on this number.
+#
+# Unfortunately the default value is in a method of an unexported object (only the constructor
+# is exported) so there is no way for us to access it without digging through the
+# internals of `cmdstanr`.
+CMDSTAN_DEFAULT_CHAINS <- 4