Merge pull request #1025 from renkun-ken/export-invisible

Add invisible param to export attribute

Author: eddelbuettel

ChangeLog

@@ -1,3 +1,8 @@
+2019-11-18  Kun Ren  <[email protected]>
+
+	* src/attributes.cpp: Add invisible param to export attribute (#1024)
+	* vignettes/rmd/Rcpp-attributes.Rmd: Add an section of Returning invisible object
+
 2019-11-13  Dirk Eddelbuettel  <[email protected]>
 
 	* .github/ISSUE_TEMPLATE.md: Another small edit
@@ -11,7 +16,7 @@
 2019-11-11  Dirk Eddelbuettel  <[email protected]>
 
 	* inst/unitTests/runit.packageversion.R: New test
-	* inst/unitTests/cpp/rcppversion.cpp: Cpp portion of test 
+	* inst/unitTests/cpp/rcppversion.cpp: Cpp portion of test
 
 2019-11-10  Dirk Eddelbuettel  <[email protected]>
 
@@ -29,14 +34,14 @@
 
 	* R/Attributes.R: Correct how cppFunction() deals with multiple
 	depends arguments
-	
+
 2019-11-08  Romain Francois  <[email protected]>
 
 	* inst/include/Rcpp/lang.h: Safer Rcpp_list* and Rcpp_lang*
 	* inst/include/Rcpp/Function.h: Add Function.invoke() for operator()
 	* inst/include/Rcpp/generated/Function__operator.h: Safer
 	Function.operator() using Function.invoke()
-	
+
 2019-11-08  Dirk Eddelbuettel  <[email protected]>
 
 	* DESCRIPTION (Date, Version): Release 1.0.3
@@ -49,7 +54,7 @@
 2019-11-06  Dirk Eddelbuettel  <[email protected]>
 
 	* DESCRIPTION (Version, Date): Roll minor version
-	
+
 	* inst/include/Rcpp/XPtr.h: Provided fallback for old constructor
 	when C++11 is not available (follow-up to #1003)
 	* inst/unitTests/runit.XPTr.R (test.XPtr): On Windows (as a proxy for
@@ -69,7 +74,7 @@
 	* inst/include/Rcpp/proxy/FieldProxy.h: Idem (inside Rf_lang3 and 4)
 
 2019-10-31  Romain Francois  <[email protected]>
-	
+
 	* inst/include/Rcpp/DataFrame.h: Protect temporaries from gc
 	* inst/include/Rcpp/Environment.h: Idem
 	* inst/include/Rcpp/r_cast.h: Idem
@@ -88,7 +93,7 @@
 	* vignettes/Rcpp-package.Rnw: Another wrapper
 	* vignettes/Rcpp-jss-2011.Rnw: Idem
 
-	* vignettes/Makefile: Refinements 
+	* vignettes/Makefile: Refinements
 	* vignettes/rmd/Makefile: Idem
 
 	* cleanup: Removed bashism, added invocation of make clean
@@ -99,7 +104,7 @@
 	* vignettes/Makefile: Added
 
 2019-10-21  Dirk Eddelbuettel  <[email protected]>
-	
+
 	* vignettes/rmd/*: Moved from parent directory
 	* vignettes/pdf/*: New target directory
 
@@ -142,7 +147,7 @@
 2019-10-01  Dirk Eddelbuettel  <[email protected]>
 
 	* DESCRIPTION (Version, Date): Roll minor version
-	
+
 2019-09-30  Kevin Ushey  <[email protected]>
 
 	* inst/include/Rcpp.h: add RCPP_NO_MODULES

src/attributes.cpp

@@ -153,6 +153,7 @@ namespace attributes {
     const char * const kExportAttribute = "export";
     const char * const kExportName = "name";
     const char * const kExportRng = "rng";
+    const char * const kExportInvisible = "invisible";
     const char * const kInitAttribute = "init";
     const char * const kDependsAttribute = "depends";
     const char * const kPluginsAttribute = "plugins";
@@ -381,6 +382,15 @@ namespace attributes {
                 return true;
         }
 
+        bool invisible() const {
+            Param invisibleParam = paramNamed(kExportInvisible);
+            if (!invisibleParam.empty())
+                return invisibleParam.value() == kParamValueTrue ||	// #nocov
+                       invisibleParam.value() == kParamValueTRUE;  	// #nocov
+            else
+                return false;
+        }
+
         const std::vector<std::string>& roxygen() const { return roxygen_; }
 
     private:
@@ -1352,7 +1362,8 @@ namespace attributes {
                 // parameter that isn't name or rng
                 else if (!value.empty() &&
                          (name != kExportName) &&
-                         (name != kExportRng)) {
+                         (name != kExportRng) &&
+                         (name != kExportInvisible)) {
                     rcppExportWarning("Unrecognized parameter '" + name + "'",
                                       lineNumber);
                 }
@@ -1366,6 +1377,16 @@ namespace attributes {
                                           lineNumber);			// #nocov end
                     }
                 }
+                // invisible that isn't true of false
+                else if (name == kExportInvisible) {
+                    if (value != kParamValueFalse &&
+                        value != kParamValueTrue &&
+                        value != kParamValueFALSE &&
+                        value != kParamValueTRUE) {
+                        rcppExportWarning("invisible value must be true or false",
+                                          lineNumber);			// #nocov end
+                    }
+                }
             }
         }
 
@@ -2413,11 +2434,14 @@ namespace attributes {
                 // determine the function name
                 std::string name = attribute.exportedName();
 
+                // determine if return invisible
+                bool  isInvisibleOrVoid = function.type().isVoid() || attribute.invisible();
+
                 // write the function
                 ostr() << name << " <- function(" << args << ") {"
                        << std::endl;
                 ostr() << "    ";
-                if (function.type().isVoid())
+                if (isInvisibleOrVoid)
                     ostr() << "invisible(";			// #nocov
                 ostr() << ".Call(";
                 if (!registration_)
@@ -2435,7 +2459,7 @@ namespace attributes {
                 for (size_t i = 0; i<arguments.size(); i++)
                     ostr() << ", " << arguments[i].name();	// #nocov
                 ostr() << ")";
-                if (function.type().isVoid())
+                if (isInvisibleOrVoid)
                     ostr() << ")";				// #nocov
                 ostr() << std::endl;