Check uris before applying them

entry.go

@@ -62,8 +62,13 @@ func NewEntry(title string) (*Entry, error) {
 		return nil, fmt.Errorf("error creating new entry: %v", err)
 	}
 
+	id, err := NewID(NewURN())
+	if err != nil {
+		return nil, fmt.Errorf("error creating new entry: %v", err)
+	}
+
 	return &Entry{
-		ID:      NewID(NewURN()),
+		ID:      id,
 		Title:   text,
 		Updated: NewDate(time.Now()),
 	}, nil

feed.go

@@ -33,8 +33,13 @@ func NewFeed(title string) (*Feed, error) {
 		return nil, fmt.Errorf("error creating new feed: %v", err)
 	}
 
+	id, err := NewID(NewURN())
+	if err != nil {
+		return nil, fmt.Errorf("error creating new feed: %v", err)
+	}
+
 	return &Feed{
-		ID:      NewID(NewURN()),
+		ID:      id,
 		Title:   text,
 		Updated: NewDate(time.Now()),
 	}, nil

icon.go

@@ -10,9 +10,13 @@ type Icon struct {
 	URI IRI `xml:",chardata"`
 }
 
-// NewIcon creates a new Icon. It returns a *Icon.
-func NewIcon(uri string) *Icon {
-	return &Icon{URI: IRI(uri)}
+// NewIcon creates a new Icon. It returns a *Icon and an error.
+func NewIcon(uri IRI) (*Icon, error) {
+	if !isValidIRI(uri) {
+		return nil, fmt.Errorf("uri %v not correctly formatted", uri)
+	}
+
+	return &Icon{URI: uri}, nil
 }
 
 // Check checks the Icon for incompatibilities with RFC4287. It returns an

id.go

@@ -10,9 +10,13 @@ type ID struct {
 	URI IRI `xml:",chardata"`
 }
 
-// NewID creates a new ID. It returns a *ID.
-func NewID(uri IRI) *ID {
-	return &ID{URI: IRI(uri)}
+// NewID creates a new ID. It returns a *ID and an error.
+func NewID(uri IRI) (*ID, error) {
+	if !isValidIRI(uri) {
+		return nil, fmt.Errorf("uri %v not correctly formatted", uri)
+	}
+
+	return &ID{URI: IRI(uri)}, nil
 }
 
 // Check checks the ID for incompatibilities with RFC4287. It returns an error.

logo.go

@@ -11,8 +11,12 @@ type Logo struct {
 }
 
 // NewLogo creates a new Logo. It returns a *Logo.
-func NewLogo(uri string) *Logo {
-	return &Logo{URI: IRI(uri)}
+func NewLogo(uri IRI) (*Logo, error) {
+	if !isValidIRI(uri) {
+		return nil, fmt.Errorf("uri %v not correctly formatted", uri)
+	}
+
+	return &Logo{URI: uri}, nil
 }
 
 // Check checks the Logo for incompatibilities with RFC4287. It returns an