Gmt module: Conversion function for GMTFont now using new parameter reading scheme and error reporting.

modules/gmt/modgmt_func.h

@@ -176,6 +176,7 @@ using Base2Proj  =Base2Struct<struct gmt_projection>;
 using Base2Color =Base2Struct<struct gmt_color>;
 using Base2Dash  =Base2Struct<struct gmt_dash>;
 using Base2Pen   =Base2Struct<struct gmt_pen>;
+using Base2Font  =Base2Struct<struct gmt_font>;
 
 // Simple aliases of convertors with default values
 using Base2StringD=Base2StructD<std::string>;
@@ -982,90 +983,52 @@ class Convert2Struct<struct gmt_font, ObjectList>
 {
  public:
 
- struct gmt_font operator()(const ObjectList* input, bool* issuc) const
+ struct gmt_font operator()(const ObjectList* input, bool* issuc, std::string& err) const
  {
   struct gmt_font f;
-  auto size=input->Size();
 
-  if(1==size) // Cases 1, 2, 4 and 5
+  if(1==input->Size()) // Cases 1, 2, 4 and 5
   {
-   Base2Font font(input,0);
+   Base2Font font;
    bool suc=true;
-   f=font(&suc);
+   f=font.Convert(input->At(0),&suc,err);
    if(!suc) goto fail; // Conversion failed
    return f;
   }
 
-  // Case 3
-  {
-   bool casevalid=false;
-   bool upd;
+  // Case 6 and 7
   {
-    BaseMT2Font updarg(input,"font");
-    bool suc=true;
-    f=updarg(&upd,&suc);
-    if(upd && !suc) goto fail; // Conversion failed or too many arguments
-   }
+   OPosPar<Base2PosD> size("size",gmt_font::default_size);
+   OPosPar<Base2ColorD> color("color",0.0);
+   OPosPar<Base2StringD> family("family",gmt_font::default_family);
 
-   if(!upd)
-   {
-    // default font is Times-Roman, 12pt, black
-    f.size=gmt_font::default_size;
-    f.color.Convert(0);
-    f.family=gmt_font::default_family;
+   ParsePositionalParameters params(input,size,family,color);
+   if(!params) goto case3; // May be case3 will work
+   f.color=color;
+   f.size=size;
+   f.family=family;
+   return f;
   }
 
-   // Size
-   {
-    BaseM2Width s(input,"s","size");
-    if(s.Exist())
+  // Case 3
+  case3:
   {
-     bool suc=true;
-     f.size=s(&suc);
-     if(!suc) goto fail; // Parsing error
-     casevalid=true;
-    }
-   }
+   ONFPar<Base2Font,ObjectGMTFont> font("f[on]t");
+   ONFPar<Base2ColorD,ObjectGMTColor> color("color",0);
+   ONFPar<Base2StringD,ObjectString> family("f[a]m[i]ly",gmt_font::default_family);
+   ONFPar<Base2PosD,ObjectReal> size("size",gmt_font::default_size);
 
-   // Family
-   {
-    BaseM2String family(input,"family","f");
-    if(family.Exist())
-    {
-     bool suc=true;
-     f.family=family(&suc);
-     if(!suc) goto fail;  // Parsing error
-     casevalid=true;
-    }
-   }
+   {ParseNamedParameters params(input,font,color,family,size); if(!params) {err=params.Error(); goto fail;} } // Fail to parse by variant 3
 
-   // Color
-   {
-    BaseMT2Color color(input,"color","c");
-    if(color.Exist())
-    {
-     bool suc=true;
-     f.color=color(&suc);
-     if(!suc) goto fail;  // Parsing error
-     casevalid=true;
-    }
-   }
+   bool upd=font.Exist();
+   if(upd) f=font;
+   if(color.Exist()  || !upd) f.color =color;
+   if(family.Exist() || !upd) f.family=family;
+   if(size.Exist()   || !upd) f.size  =size;
 
-   if(casevalid || upd) return f; // Pen created or updated
-  }
 
-  // Case 6 and 7
-  if(2==size || 3==size)
-  {
-   Base2Width s(input,0);
-   Base2String fam(input,1);
-   Base2Color c(input,2);
-   bool suc=true;
-   f.size=s(&suc);
-   f.family=fam(&suc);
-   f.color=c(&suc);
-   if(!suc) goto fail; // Something wrong
-   return f;
+   if(color.Exist() || family.Exist() || size.Exist() || upd) return f; // Font created or updated
+   err="Specify at least one of size, family or color";
   }
 
   fail: