Added GAP_AssignGlobalVariable and GAP_IsNameOfWritableGlobalVariable

to libgap-api

src/libgap-api.c

@@ -95,6 +95,17 @@ Obj GAP_ValueGlobalVariable(const char * name)
     }
 }
 
+int GAP_IsNameOfWritableGlobalVariable(const char * name)
+{
+    UInt gvar = GVarName(name);
+    return !(IsReadOnlyGVar(gvar) || IsConstantGVar(gvar));
+}
+
+void GAP_AssignGlobalVariable(const char * name, Obj value)
+{
+    UInt gvar = GVarName(name);
+    AssGVar(gvar, value);
+}
 
 ////
 //// arithmetic

src/libgap-api.h

@@ -179,6 +179,14 @@ Obj GAP_EvalString(const char * cmd);
 // defined.
 Obj GAP_ValueGlobalVariable(const char * name);
 
+// Checks if <name> belongs to a writable GVar
+int GAP_IsNameOfWritableGlobalVariable(const char * name);
+
+// Combines GVarName and AssGVar. For a given <name> and <value>,
+// it assigns <value> to the global <name>. The function may raise
+// an error if <name> refers to a readonly variable.
+void GAP_AssignGlobalVariable(const char * name, Obj value);
+
 
 ////
 //// arithmetic

tst/testlibgap/api.c

@@ -138,13 +138,24 @@ void operations(void)
 void globalvars(void)
 {
     Obj a;
+    int x;
 
     a = GAP_ValueGlobalVariable("yaddayaddayadda");
     assert(a == 0);
 
     // Hopefully this always exists.
     a = GAP_ValueGlobalVariable("GAPInfo");
     assert(GAP_IsRecord(a) != 0);
+
+    x = GAP_IsNameOfWritableGlobalVariable("GAPInfo");
+    assert(x == 0);
+
+    x = GAP_IsNameOfWritableGlobalVariable("GAPInfo_copy");
+    assert(x != 0);
+
+    GAP_AssignGlobalVariable("GAPInfo_copy", a);
+    a = GAP_ValueGlobalVariable("GAPInfo_copy");
+    assert(a != 0);
 }
 
 int main(int argc, char ** argv)