Change readme accordingly

README.md

@@ -15,8 +15,8 @@ go get git.streifling.com/jason/atom@latest
 ## Usage
 
 This library provides convenient functions to safely create and extend elements
-and attributes of an Atom feed. This is because it can be hard to know all
-pitfalls of RFC4287. The intended way of using atom is with these functions.
+and attributes of Atom feeds. It also provides checks for all constructs'
+adherence to RFC4287.
 
 ```go
 package main
@@ -29,30 +29,28 @@ import (
 )
 
 func main() {
- feed, err := atom.NewFeed("Example Feed")
- if err != nil {
+ feed := atom.NewFeed("Example Feed")
+ feed.Title = atom.NewText("text", "Example Feed")
+ feed.ID = atom.NewID(atom.NewURN())
+ if err := feed.Check(); err != nil {
   log.Fatalln(err)
  }
 
  author := atom.NewPerson("John Doe")
  author.Email = "john.doe@example.com"
+ if err := author.Check(); err != nil {
+  log.Fatalln(err)
+ }
  feed.AddAuthor(author)
 
- entry, err := atom.NewEntry("First Entry")
- if err != nil {
+ entry := atom.NewEntry("First Entry")
+ entry.ID = atom.NewID(atom.NewURN())
+ entry.Content = atom.NewContent(atom.InlineText, "text", "This is the content of the first entry.")
+ if err := entry.Check(); err != nil {
   log.Fatalln(err)
  }
- content, err := atom.NewContent(atom.InlineText, "text", "This is the content of the first entry.")
- if err != nil {
-  log.Fatalln(err)
- }
- entry.Content = content
  feed.AddEntry(entry)
 
- if err := feed.Check(); err != nil {
-  log.Fatalln(err)
- }
-
  feedString, err := feed.ToXML("utf-8")
  if err != nil {
   log.Fatalln(err)
@@ -62,7 +60,7 @@ func main() {
 ```
 
 It is also possible to use this library in a way similar to what other libraries
-would provide. This is, of course, making it easier to make mistakes.
+provide.
 
 ```go
 package main
@@ -115,7 +113,7 @@ func main() {
 }
 ```
 
-The output of both ways of using it is an RFC4287 compliant Atom feed:
+The output of both ways of using it is an RFC4287 compliant Atom feed.
 
 ```xml
 <?xml version="1.0" encoding="utf-8"?>

atom.go

@@ -2,6 +2,7 @@ package atom
 
 import (
 	"fmt"
+	"html"
 	"mime"
 	"regexp"
 	"strings"
@@ -85,3 +86,8 @@ func isValidAttribute(attribute string) bool {
 func NewURN() string {
 	return fmt.Sprint("urn:uuid:", uuid.New())
 }
+
+// Unescape unescapes a string. It returns an IRI.
+func Unescape(s string) string {
+	return html.UnescapeString(s)
+}

category.go

@@ -2,9 +2,7 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
-	"html"
 )
 
 type Category struct {
@@ -15,43 +13,17 @@ type Category struct {
 	Label  string `xml:"label,attr,omitempty"`
 }
 
-// NewCategory creates a new Category. It returns a *Category and an error.
-func NewCategory(term string) (*Category, error) {
-	if term == "" {
-		return nil, errors.New("error creating new category: term string empty")
+// NewCategory creates a new Category. It returns a *Category.
+func NewCategory(term string) *Category {
+	return &Category{
+		CommonAttributes: newCommonAttributes(),
+		Term:             term,
+	}
 }
 
-	return &Category{Term: term}, nil
-}
-
-// SetTerm sets the Term attribute of the Category. It returns an error.
-func (c *Category) SetTerm(t string) error {
-	if t == "" {
-		return errors.New("error setting term of category: t string empty")
-	}
-
-	c.Term = t
-	return nil
-}
-
-// SetScheme sets the Scheme attribute of the Category. It returns an error.
-func (c *Category) SetScheme(s string) error {
-	if !isValidIRI(s) {
-		return fmt.Errorf("scheme %v not correctly formatted", s)
-	}
-
-	c.Scheme = s
-	return nil
-}
-
-// SetLabel sets the Label attribute of the Category. It returns an error.
-func (c *Category) SetLabel(label string) error {
-	if label == "" {
-		return errors.New("error setting label of category: label string empty")
-	}
-
-	c.Label = html.UnescapeString(label)
-	return nil
+// SetLabel sets the Label attribute of the Category.
+func (c *Category) SetLabel(label string) {
+	c.Label = Unescape(label)
 }
 
 // Check checks the Category for incompatibilities with RFC4287. It returns an

commonAttributes.go

@@ -2,7 +2,7 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
+	"fmt"
 )
 
 type CommonAttributes struct {
@@ -13,25 +13,31 @@ type CommonAttributes struct {
 
 // NewCommonAttributes creates a new set of CommonAttributes. It returns a
 // *CommonAttributes.
-func NewCommonAttributes() *CommonAttributes {
+func newCommonAttributes() *CommonAttributes {
 	return new(CommonAttributes)
 }
 
-// AddAttribute adds the Attribute to the CommonAttributes. It returns an error.
-func (c *CommonAttributes) AddAttribute(name, value string) error {
-	if name == "" {
-		return errors.New("error adding attribute: name string empty")
-	}
-	if value == "" {
-		return errors.New("error adding attribute: value string empty")
-	}
-
+// AddAttribute adds the Attribute to the CommonAttributes.
+func (c *CommonAttributes) AddAttribute(name, value string) {
 	if c.UndefinedAttributes == nil {
 		c.UndefinedAttributes = make([]*xml.Attr, 1)
 		c.UndefinedAttributes[0] = &xml.Attr{Name: xml.Name{Local: name}, Value: value}
 	} else {
 		c.UndefinedAttributes = append(c.UndefinedAttributes, &xml.Attr{Name: xml.Name{Local: name}, Value: value})
 	}
+}
+
+// Check checks the CommonAttributes for incompatibilities with RFC4287. It
+// returns an error.
+func (c *CommonAttributes) Check() error {
+	for i, u := range c.UndefinedAttributes {
+		if u.Name.Local == "" {
+			return fmt.Errorf("xml name of undefined attribute %v empty", i)
+		}
+		if u.Value == "" {
+			return fmt.Errorf("value of undefined attribute %v empty", i)
+		}
+	}
 
 	return nil
 }

content.go

@@ -1,7 +1,5 @@
 package atom
 
-import "fmt"
-
 const (
 	InlineText = iota
 	InlineXHTML
@@ -17,17 +15,17 @@ type Content interface {
 }
 
 // NewContent creates a new Content. It returns a Content and an error.
-func NewContent(contentType int, mediaType string, content any) (Content, error) {
+func NewContent(contentType int, mediaType string, content any) Content {
 	switch contentType {
 	case 0:
-		return newInlineTextContent(mediaType, content)
+		return newInlineTextContent(mediaType, content.(string))
 	case 1:
-		return newInlineXHTMLContent(mediaType, content)
+		return newInlineXHTMLContent(mediaType, content.(*XHTMLDiv))
 	case 2:
 		return newInlineOtherContent(mediaType, content)
 	case 3:
-		return newOutOfLineContent(mediaType, content)
+		return newOutOfLineContent(mediaType, content.(string))
 	default:
-		return nil, fmt.Errorf("error creating new content: %v is not a valid text type", contentType)
+		return nil
 	}
 }

date.go

@@ -18,7 +18,10 @@ func DateTime(t time.Time) string {
 
 // NewDate creates a new Date. It returns a *Date.
 func NewDate(t time.Time) *Date {
-	return &Date{DateTime: DateTime(t)}
+	return &Date{
+		CommonAttributes: newCommonAttributes(),
+		DateTime:         DateTime(t),
+	}
 }
 
 // Check checks the Date for incompatibilities with RFC4287. It returns an

entry.go

@@ -2,7 +2,6 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -57,31 +56,18 @@ func (e *Entry) checkAuthors(authorInFeed bool) error {
 	return nil
 }
 
-// NewEntry creates a new Entry. It returns a *Entry and an error.
-func NewEntry(title string) (*Entry, error) {
-	text, err := NewText("text", title)
-	if err != nil {
-		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)
-	}
-
+// NewEntry creates a new Entry. It returns a *Entry.
+func NewEntry(title string) *Entry {
 	return &Entry{
-		ID:      id,
-		Title:   text,
+		CommonAttributes: newCommonAttributes(),
+		ID:               NewID(NewURN()),
+		Title:            NewText("text", title),
 		Updated:          NewDate(time.Now()),
-	}, nil
-}
-
-// AddAuthor adds the Person as an author to the Entry. It returns an error.
-func (e *Entry) AddAuthor(p *Person) error {
-	if p == nil {
-		return errors.New("error adding author element to entry: *Person is nil")
+	}
 }
 
+// AddAuthor adds the Person as an author to the Entry.
+func (e *Entry) AddAuthor(p *Person) {
 	if e.Authors == nil {
 		e.Authors = make([]*Person, 1)
 		e.Authors[0] = p
@@ -90,15 +76,10 @@ func (e *Entry) AddAuthor(p *Person) error {
 	}
 
 	e.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddCategory adds the Category to the Entry. It returns an error.
-func (e *Entry) AddCategory(c *Category) error {
-	if c == nil {
-		return errors.New("error adding category element to entry: *Category is nil")
 }
 
+// AddCategory adds the Category to the Entry.
+func (e *Entry) AddCategory(c *Category) {
 	if e.Categories == nil {
 		e.Categories = make([]*Category, 1)
 		e.Categories[0] = c
@@ -107,16 +88,10 @@ func (e *Entry) AddCategory(c *Category) error {
 	}
 
 	e.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddContributor adds the Person as a contributor to the Entry. It returns an
-// error.
-func (e *Entry) AddContributor(c *Person) error {
-	if c == nil {
-		return errors.New("error adding contributor element to entry: *Person is nil")
 }
 
+// AddContributor adds the Person as a contributor to the Entry.
+func (e *Entry) AddContributor(c *Person) {
 	if e.Contributors == nil {
 		e.Contributors = make([]*Person, 1)
 		e.Contributors[0] = c
@@ -125,15 +100,10 @@ func (e *Entry) AddContributor(c *Person) error {
 	}
 
 	e.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddLink adds the Link to the Entry. It returns an error.
-func (e *Entry) AddLink(l *Link) error {
-	if l == nil {
-		return errors.New("error adding link element to entry: *Link is nil")
 }
 
+// AddLink adds the Link to the Entry.
+func (e *Entry) AddLink(l *Link) {
 	if e.Links == nil {
 		e.Links = make([]*Link, 1)
 		e.Links[0] = l
@@ -142,15 +112,10 @@ func (e *Entry) AddLink(l *Link) error {
 	}
 
 	e.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddExtension adds the ExtensionElement to the Entry. It returns an error.
-func (e *Entry) AddExtension(x *ExtensionElement) error {
-	if x == nil {
-		return errors.New("error adding extension element to entry: *ExtensionElement is nil")
 }
 
+// AddExtension adds the ExtensionElement to the Entry.
+func (e *Entry) AddExtension(x *ExtensionElement) {
 	if e.Extensions == nil {
 		e.Extensions = make([]*ExtensionElement, 1)
 		e.Extensions[0] = x
@@ -159,7 +124,6 @@ func (e *Entry) AddExtension(x *ExtensionElement) error {
 	}
 
 	e.Updated.DateTime = DateTime(time.Now())
-	return nil
 }
 
 // Check checks the Entry for incompatibilities with RFC4287. It returns an

extensionElement.go

@@ -2,7 +2,7 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
+	"fmt"
 )
 
 type ExtensionElement struct {
@@ -11,27 +11,20 @@ type ExtensionElement struct {
 }
 
 // NewExtensionElement creates a new ExtensionElement. It returns a
-// *ExtensionElement and an error.
-func NewExtensionElement(name string, value any) (*ExtensionElement, error) {
-	if name == "" {
-		return nil, errors.New("error adding extension attribute: name string empty")
-	}
-	if value == "" {
-		return nil, errors.New("error adding extension attribute: value string empty")
-	}
-
-	return &ExtensionElement{XMLName: xml.Name{Local: name}, Value: value}, nil
+// *ExtensionElement.
+func NewExtensionElement(name string, value any) *ExtensionElement {
+	return &ExtensionElement{XMLName: xml.Name{Local: name}, Value: value}
 }
 
 // Check checks the ExtensionElement for incompatibilities with RFC4287. It
 // returns an error.
 func (e *ExtensionElement) Check() error {
 	if e.XMLName.Local == "" {
-		return errors.New("xml name of extension empty")
+		return fmt.Errorf("xml name of extension %v empty", e)
 	}
 
 	if e.Value == nil {
-		return errors.New("value element of extension empty")
+		return fmt.Errorf("value of extension %v empty", e)
 	}
 
 	return nil

feed.go

@@ -2,7 +2,6 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
 	"time"
 )
@@ -26,31 +25,18 @@ type Feed struct {
 	Entries      []*Entry            `xml:",omitempty"`
 }
 
-// NewFeed creates a new Feed. It returns a *Feed and an error.
-func NewFeed(title string) (*Feed, error) {
-	text, err := NewText("text", title)
-	if err != nil {
-		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)
-	}
-
+// NewFeed creates a new Feed. It returns a *Feed.
+func NewFeed(title string) *Feed {
 	return &Feed{
-		ID:      id,
-		Title:   text,
+		CommonAttributes: newCommonAttributes(),
+		ID:               NewID(NewURN()),
+		Title:            NewText("text", title),
 		Updated:          NewDate(time.Now()),
-	}, nil
-}
-
-// AddAuthor adds the Person as an author to the Feed. It returns an error.
-func (f *Feed) AddAuthor(p *Person) error {
-	if p == nil {
-		return errors.New("error adding author element to feed: *Person is nil")
+	}
 }
 
+// AddAuthor adds the Person as an author to the Feed.
+func (f *Feed) AddAuthor(p *Person) {
 	if f.Authors == nil {
 		f.Authors = make([]*Person, 1)
 		f.Authors[0] = p
@@ -59,15 +45,10 @@ func (f *Feed) AddAuthor(p *Person) error {
 	}
 
 	f.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddCategory adds the Category to the Feed. It returns an error.
-func (f *Feed) AddCategory(c *Category) error {
-	if c == nil {
-		return errors.New("error adding category element to feed: *Category is nil")
 }
 
+// AddCategory adds the Category to the Feed.
+func (f *Feed) AddCategory(c *Category) {
 	if f.Categories == nil {
 		f.Categories = make([]*Category, 1)
 		f.Categories[0] = c
@@ -76,16 +57,10 @@ func (f *Feed) AddCategory(c *Category) error {
 	}
 
 	f.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddContributor adds the Person as a contributor to the Feed. It returns an
-// error.
-func (f *Feed) AddContributor(c *Person) error {
-	if c == nil {
-		return errors.New("error adding contributor element to feed: *Person is nil")
 }
 
+// AddContributor adds the Person as a contributor to the Feed.
+func (f *Feed) AddContributor(c *Person) {
 	if f.Contributors == nil {
 		f.Contributors = make([]*Person, 1)
 		f.Contributors[0] = c
@@ -94,16 +69,10 @@ func (f *Feed) AddContributor(c *Person) error {
 	}
 
 	f.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddLink adds the Link to the Feed. It returns an error. There should be one
-// Link with Rel "self".
-func (f *Feed) AddLink(l *Link) error {
-	if l == nil {
-		return errors.New("error adding link element to feed: *Link is nil")
 }
 
+// AddLink adds the Link to the Feed. There should be one Link with Rel "self".
+func (f *Feed) AddLink(l *Link) {
 	if f.Links == nil {
 		f.Links = make([]*Link, 1)
 		f.Links[0] = l
@@ -112,15 +81,10 @@ func (f *Feed) AddLink(l *Link) error {
 	}
 
 	f.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddExtension adds the Extension to the Feed. It returns an error.
-func (f *Feed) AddExtension(e *ExtensionElement) error {
-	if e == nil {
-		return errors.New("error adding extension element to feed: *ExtensionElement is nil")
 }
 
+// AddExtension adds the Extension to the Feed.
+func (f *Feed) AddExtension(e *ExtensionElement) {
 	if f.Extensions == nil {
 		f.Extensions = make([]*ExtensionElement, 1)
 		f.Extensions[0] = e
@@ -129,15 +93,10 @@ func (f *Feed) AddExtension(e *ExtensionElement) error {
 	}
 
 	f.Updated.DateTime = DateTime(time.Now())
-	return nil
-}
-
-// AddEntry adds the Entry to the Feed. It returns an error.
-func (f *Feed) AddEntry(e *Entry) error {
-	if e == nil {
-		return errors.New("error adding entry element to feed: *Entry is nil")
 }
 
+// AddEntry adds the Entry to the Feed.
+func (f *Feed) AddEntry(e *Entry) {
 	if f.Entries == nil {
 		f.Entries = make([]*Entry, 1)
 		f.Entries[0] = e
@@ -146,7 +105,6 @@ func (f *Feed) AddEntry(e *Entry) error {
 	}
 
 	f.Updated.DateTime = DateTime(time.Now())
-	return nil
 }
 
 // Check checks the Feed for incompatibilities with RFC4287. It returns an

generator.go

@@ -2,7 +2,6 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
 	"html"
 )
@@ -15,22 +14,12 @@ type Generator struct {
 	Text    string `xml:",chardata"`
 }
 
-// NewGenerator creates a new Generator. It returns a *Generator and an error.
-func NewGenerator(text string) (*Generator, error) {
-	if text == "" {
-		return nil, errors.New("error creating new generator: text string empty")
+// NewGenerator creates a new Generator. It returns a *Generator.
+func NewGenerator(text string) *Generator {
+	return &Generator{
+		CommonAttributes: newCommonAttributes(),
+		Text:             html.UnescapeString(text),
 	}
-
-	return &Generator{Text: html.UnescapeString(text)}, nil
-}
-
-// SetURI sets the URI attribute of the Generator. It returns an error.
-func (g *Generator) SetURI(uri string) error {
-	if !isValidIRI(uri) {
-		return fmt.Errorf("uri %v not correctly formatted", g)
-	}
-
-	return nil
 }
 
 // Check checks the Generator for incompatibilities with RFC4287. It returns an

icon.go

@@ -12,13 +12,12 @@ type Icon struct {
 	URI string `xml:",chardata"` // IRI
 }
 
-// NewIcon creates a new Icon. It returns a *Icon and an error.
-func NewIcon(uri string) (*Icon, error) {
-	if !isValidIRI(uri) {
-		return nil, fmt.Errorf("uri %v not correctly formatted", uri)
+// NewIcon creates a new Icon. It returns a *Icon.
+func NewIcon(uri string) *Icon {
+	return &Icon{
+		CommonAttributes: newCommonAttributes(),
+		URI:              uri,
 	}
-
-	return &Icon{URI: uri}, nil
 }
 
 // Check checks the Icon for incompatibilities with RFC4287. It returns an

id.go

@@ -12,13 +12,12 @@ type ID struct {
 	URI string `xml:",chardata"` // IRI
 }
 
-// NewID creates a new ID. It returns a *ID and an error.
-func NewID(uri string) (*ID, error) {
-	if !isValidIRI(uri) {
-		return nil, fmt.Errorf("uri %v not correctly formatted", uri)
+// NewID creates a new ID. It returns a *ID.
+func NewID(uri string) *ID {
+	return &ID{
+		CommonAttributes: newCommonAttributes(),
+		URI:              uri,
 	}
-
-	return &ID{URI: uri}, nil
 }
 
 // Check checks the ID for incompatibilities with RFC4287. It returns an error.

inlineOtherContent.go

@@ -15,13 +15,14 @@ type InlineOtherContent struct {
 
 // newInlineOtherContent creates a new InlineOtherContent. It returns a
 // *InlineOtherContent and an error.
-func newInlineOtherContent(mediaType string, content any) (*InlineOtherContent, error) {
-	if !isValidMediaType(mediaType) {
-		return nil, fmt.Errorf("error creating new inline other content: media type %v invalid", mediaType)
-	}
+func newInlineOtherContent(mediaType string, content any) *InlineOtherContent {
 	mediaType, _, _ = mime.ParseMediaType(mediaType)
 
-	return &InlineOtherContent{Type: mediaType, AnyElement: content}, nil
+	return &InlineOtherContent{
+		CommonAttributes: newCommonAttributes(),
+		Type:             mediaType,
+		AnyElement:       content,
+	}
 }
 
 // isContent checks whether the InlineOtherContent is a Content. It returns a

inlineTextContent.go

@@ -13,18 +13,13 @@ type InlineTextContent struct {
 }
 
 // newInlineTextContent creates a new InlineTextContent. It returns a
-// *InlineTextContent and an error.
-func newInlineTextContent(mediaType string, content any) (*InlineTextContent, error) {
-	if mediaType != "text" && mediaType != "html" && mediaType != "" {
-		return nil, fmt.Errorf("media type %v incompatible with inline text content", mediaType)
+// *InlineTextContent.
+func newInlineTextContent(mediaType, text string) *InlineTextContent {
+	return &InlineTextContent{
+		CommonAttributes: newCommonAttributes(),
+		Type:             mediaType,
+		Text:             text,
 	}
-
-	text, ok := content.(string)
-	if !ok {
-		return nil, fmt.Errorf("content type %T incompatible with inline text content", content)
-	}
-
-	return &InlineTextContent{Type: mediaType, Text: text}, nil
 }
 
 // isContent checks whether the InlineTextContent is a Content. It returns a

inlineXHTMLContent.go

@@ -13,18 +13,13 @@ type InlineXHTMLContent struct {
 }
 
 // newInlineXHTMLContent creates a new InlineXHTMLContent. It returns a
-// *InlineXHTMLContent and an error.
-func newInlineXHTMLContent(mediaType string, content any) (*InlineXHTMLContent, error) {
-	if mediaType != "xhtml" {
-		return nil, fmt.Errorf("media type %v incompatible with inline xhtml content", mediaType)
+// *InlineXHTMLContent.
+func newInlineXHTMLContent(mediaType string, div *XHTMLDiv) *InlineXHTMLContent {
+	return &InlineXHTMLContent{
+		CommonAttributes: newCommonAttributes(),
+		Type:             mediaType,
+		XHTMLDiv:         div,
 	}
-
-	xhtmlDiv, ok := content.(*XHTMLDiv)
-	if !ok {
-		return nil, fmt.Errorf("content type %T incompatible with inline xhtml content", content)
-	}
-
-	return &InlineXHTMLContent{Type: mediaType, XHTMLDiv: xhtmlDiv}, nil
 }
 
 // isContent checks whether the InlineXHTMLContent is a Content. It returns a

link.go

@@ -17,31 +17,12 @@ type Link struct {
 	Length   uint   `xml:"length,attr,omitempty"`
 }
 
-// NewLink creates a new Link. It returns a *Link and an error.
-func NewLink(href string) (*Link, error) {
-	if !isValidIRI(href) {
-		return nil, fmt.Errorf("href %v not correctly formatted", href)
+// NewLink creates a new Link. It returns a *Link.
+func NewLink(href string) *Link {
+	return &Link{
+		CommonAttributes: newCommonAttributes(),
+		Href:             href,
 	}
-
-	return &Link{Href: href}, nil
-}
-
-// SetType sets the Type attribute of the Link. It returns an error.
-func (l *Link) SetType(t string) error {
-	if !isValidMediaType(t) {
-		return fmt.Errorf("type %v invalid media type", l)
-	}
-
-	return nil
-}
-
-// SetHrefLang sets the HrefLang attribute of the Link. It returns an error.
-func (l *Link) SetHrefLang(h string) error {
-	if !isValidLanguageTag(h) {
-		return fmt.Errorf("hreflang %v invalid language tag", l)
-	}
-
-	return nil
 }
 
 // Check checks the Link for incompatibilities with RFC4287. It returns an

logo.go

@@ -11,13 +11,12 @@ type Logo struct {
 	URI string `xml:",chardata"` // IRI
 }
 
-// NewLogo creates a new Logo. It returns a *Logo and an error.
-func NewLogo(uri string) (*Logo, error) {
-	if !isValidIRI(uri) {
-		return nil, fmt.Errorf("uri %v not correctly formatted", uri)
+// NewLogo creates a new Logo. It returns a *Logo.
+func NewLogo(uri string) *Logo {
+	return &Logo{
+		CommonAttributes: newCommonAttributes(),
+		URI:              uri,
 	}
-
-	return &Logo{URI: uri}, nil
 }
 
 // Check checks the Logo for incompatibilities with RFC4287. It returns an

outOfLineContent.go

@@ -14,23 +14,15 @@ type OutOfLineContent struct {
 }
 
 // newOutOfLineContent creates a new OutOfLineContent. It returns a
-// *OutOfLineContent and an error.
-func newOutOfLineContent(mediaType string, content any) (*OutOfLineContent, error) {
-	if !isValidMediaType(mediaType) {
-		return nil, fmt.Errorf("error creating new out of line content: media type %v invalid", mediaType)
-	}
+// *OutOfLineContent.
+func newOutOfLineContent(mediaType, src string) *OutOfLineContent {
 	mediaType, _, _ = mime.ParseMediaType(mediaType)
 
-	iri, ok := content.(string)
-	if !ok {
-		return nil, fmt.Errorf("content type %T incompatible with out of line content", content)
+	return &OutOfLineContent{
+		CommonAttributes: newCommonAttributes(),
+		Type:             mediaType,
+		SRC:              src,
 	}
-
-	if !isValidIRI(iri) {
-		return nil, fmt.Errorf("content %v not a valid uri", iri)
-	}
-
-	return &OutOfLineContent{Type: mediaType, SRC: iri}, nil
 }
 
 // isContent checks whether the OutOfLineContent is a Content. It returns a

person.go

@@ -1,7 +1,6 @@
 package atom
 
 import (
-	"errors"
 	"fmt"
 	"net/mail"
 )
@@ -14,38 +13,22 @@ type Person struct {
 	Extensions []*ExtensionElement `xml:",any,omitempty"`
 }
 
-// NewPerson creates a new Person. It returns a *Person and an error.
-func NewPerson(name string) (*Person, error) {
-	if name == "" {
-		return nil, errors.New("error creating new person: name string empty")
-	}
-
-	return &Person{Name: name}, nil
-}
-
-// SetURI sets the URI element of the Person. It returns an error.
-func (l *Link) SetURI(uri string) error {
-	if !isValidIRI(uri) {
-		return fmt.Errorf("uri %v not correctly formatted", uri)
-	}
-
-	return nil
-}
-
-// AddExtension adds the Extension to the Person. It returns an error.
-func (p *Person) AddExtension(e *ExtensionElement) error {
-	if e == nil {
-		return errors.New("error adding extension element to person: *ExtensionElement is nil")
+// NewPerson creates a new Person. It returns a *Person.
+func NewPerson(name string) *Person {
+	return &Person{
+		CommonAttributes: newCommonAttributes(),
+		Name:             name,
+	}
 }
 
+// AddExtension adds the Extension to the Person.
+func (p *Person) AddExtension(e *ExtensionElement) {
 	if p.Extensions == nil {
 		p.Extensions = make([]*ExtensionElement, 1)
 		p.Extensions[0] = e
 	} else {
 		p.Extensions = append(p.Extensions, e)
 	}
-
-	return nil
 }
 
 // Check checks the Person for incompatibilities with RFC4287. It returns an

plainText.go

@@ -1,7 +1,6 @@
 package atom
 
 import (
-	"errors"
 	"fmt"
 )
 
@@ -14,13 +13,13 @@ type PlainText struct {
 // isText checks whether the PlainText is a Text. It returns a bool.
 func (p *PlainText) isText() bool { return true }
 
-// newPlainText creates a new PlainText. It returns a *PlainText and an error.
-func newPlainText(textType, content string) (*PlainText, error) {
-	if content == "" {
-		return nil, errors.New("error creating new plain text: content string empty")
+// newPlainText creates a new PlainText. It returns a *PlainText.
+func newPlainText(textType, content string) *PlainText {
+	return &PlainText{
+		CommonAttributes: newCommonAttributes(),
+		Type:             textType,
+		Text:             content,
 	}
-
-	return &PlainText{Type: textType, Text: content}, nil
 }
 
 // Check checks the PlainText for incompatibilities with RFC4287. It returns an

source.go

@@ -25,7 +25,7 @@ type Source struct {
 
 // NewSource creates a new Source. It returns a *Source.
 func NewSource() *Source {
-	return new(Source)
+	return &Source{CommonAttributes: newCommonAttributes()}
 }
 
 // Check checks the Source for incompatibilities with RFC4287. It returns an

text.go

@@ -1,17 +1,14 @@
 package atom
 
-import (
-	"fmt"
-	"html"
-)
+import "html"
 
 type Text interface {
 	isText() bool
 	Check() error
 }
 
-// NewText creates a new Text. It returns a Text and an error.
-func NewText(textType, content string) (Text, error) {
+// NewText creates a new Text. It returns a Text.
+func NewText(textType, content string) Text {
 	switch textType {
 	case "text", "":
 		return newPlainText(textType, content)
@@ -20,6 +17,6 @@ func NewText(textType, content string) (Text, error) {
 	case "xhtml":
 		return newXHTMLText(textType, content)
 	default:
-		return nil, fmt.Errorf("%v is not a valid text type", textType)
+		return nil
 	}
 }

xhtmlDiv.go

@@ -2,7 +2,6 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
 )
 
@@ -12,16 +11,12 @@ type XHTMLDiv struct {
 	Content string   `xml:",innerxml"`
 }
 
-// NewXHTMLDiv creates a new XHTMLDiv. It returns a *XHTMLDiv and an error.
-func NewXHTMLDiv(content string) (*XHTMLDiv, error) {
-	if content == "" {
-		return nil, errors.New("error creating new xhtml div: content string empty")
-	}
-
+// NewXHTMLDiv creates a new XHTMLDiv. It returns a *XHTMLDiv.
+func NewXHTMLDiv(content string) *XHTMLDiv {
 	return &XHTMLDiv{
 		XMLNS:   "http://www.w3.org/1999/xhtml",
 		Content: content,
-	}, nil
+	}
 }
 
 // Check checks the XHTMLDiv for incompatibilities with RFC4287. It returns an

xhtmlText.go

@@ -13,17 +13,13 @@ type XHTMLText struct {
 // isText checks whether the XHTMLText is a Text. It returns a bool.
 func (x *XHTMLText) isText() bool { return true }
 
-// newPlainText creates a new PlainText. It returns a *PlainText and an error.
-func newXHTMLText(textType, content string) (*XHTMLText, error) {
-	xhtmlDiv, err := NewXHTMLDiv(content)
-	if err != nil {
-		return nil, fmt.Errorf("error creating new xhtml text: %v", err)
-	}
-
+// newPlainText creates a new PlainText. It returns a *PlainText.
+func newXHTMLText(textType, content string) *XHTMLText {
 	return &XHTMLText{
+		CommonAttributes: newCommonAttributes(),
 		Type:             textType,
-		XHTMLDiv: xhtmlDiv,
-	}, nil
+		XHTMLDiv:         NewXHTMLDiv(content),
+	}
 }
 
 // Check checks the XHTMLText for incompatibilities with RFC4287. It returns an