Touched up README

README.md

@@ -2,7 +2,7 @@
 
 An extensible Atom feed generator library that aims to be very close to RFC4287.
 It diligently checks for compliance with the standard and provides functions for
-easy creation and extension of elements.
+easy creation, extension and deletion of elements.
 
 ## Installation
 
@@ -14,45 +14,47 @@ go get git.streifling.com/jason/atom@latest
 
 ## Usage
 
-This library provides convenient functions to safely create and extend elements
-and attributes of Atom feeds. It also provides checks for all constructs'
-adherence to RFC4287.
+### Basic Feed
+
+This library provides convenient functions to safely create, extend and delete
+elements and attributes of Atom feeds. It also provides checks for all
+constructs' adherence to RFC4287.
 
 ```go
 package main
 
 import (
- "fmt"
- "log"
+    "fmt"
+    "log"
 
- "git.streifling.com/jason/atom"
+    "git.streifling.com/jason/atom"
 )
 
 func main() {
- feed := atom.NewFeed("Example Feed")
- if err := feed.Check(); err != nil {
-  log.Fatalln(err)
- }
+    feed := atom.NewFeed("Example Feed")
+    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)
+    author := atom.NewPerson("John Doe")
+    author.Email = "john.doe@example.com"
+    if err := author.Check(); err != nil {
+        log.Fatalln(err)
+    }
+    feed.AddAuthor(author)
 
- entry := atom.NewEntry("First Entry")
- entry.Content = atom.NewContent(atom.InlineText, "text", "This is the content of the first entry.")
- if err := entry.Check(); err != nil {
-  log.Fatalln(err)
- }
- feed.AddEntry(entry)
+    entry := atom.NewEntry("First Entry")
+    entry.Content = atom.NewContent(atom.InlineText, "text", "This is the content of the first entry.")
+    if err := entry.Check(); err != nil {
+        log.Fatalln(err)
+    }
+    feed.AddEntry(entry)
 
- feedString, err := feed.ToXML("utf-8")
- if err != nil {
-  log.Fatalln(err)
- }
- fmt.Println(feedString)
+    feedString, err := feed.ToXML("UTF-8")
+    if err != nil {
+        log.Fatalln(err)
+    }
+    fmt.Println(feedString)
 }
 ```
 
@@ -63,70 +65,177 @@ provide.
 package main
 
 import (
- "fmt"
- "log"
- "time"
+    "fmt"
+    "log"
+    "time"
 
- "git.streifling.com/jason/atom"
+    "git.streifling.com/jason/atom"
+    "github.com/google/uuid"
 )
 
 func main() {
- now := time.Now()
+    now := time.Now()
 
- feed := &atom.Feed{
-  Title: &atom.PlainText{
-   Type: "text",
-   Text: "Example Feed",
-  },
-  ID:      &atom.ID{URI: "urn:uuid:60a76c80-d399-11d9-b93C-0003939e0af6"},
-  Updated: &atom.Date{DateTime: atom.DateTime(now)},
-  Authors: []*atom.Person{
-   {
-    Name:  "John Doe",
-    Email: "john.doe@example.com",
-   },
-  },
-  Entries: []*atom.Entry{
-   {
-    Title: &atom.PlainText{
-     Type: "text",
-     Text: "First Entry",
-    },
-    ID:      &atom.ID{URI: "urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a"},
-    Updated: &atom.Date{DateTime: atom.DateTime(now)},
-    Content: &atom.InlineTextContent{
-     Type: "text",
-     Text: "This is the content of the first entry.",
-    },
-   },
-  },
- }
+    feed := &atom.Feed{
+        Title: &atom.PlainText{
+            Type: "text",
+            Text: "Example Feed",
+        },
+        ID:      &atom.ID{URI: fmt.Sprint("urn:uuid:", uuid.New())},
+        Updated: &atom.Date{DateTime: atom.DateTime(now)},
+        Authors: []*atom.Person{
+            {
+                Name:  "John Doe",
+                Email: "john.doe@example.com",
+            },
+        },
+        Entries: []*atom.Entry{
+            {
+                Title: &atom.PlainText{
+                    Type: "text",
+                    Text: "First Entry",
+                },
+                ID:      &atom.ID{URI: fmt.Sprint("urn:uuid:", uuid.New())},
+                Updated: &atom.Date{DateTime: atom.DateTime(now)},
+                Content: &atom.InlineTextContent{
+                    Type: "text",
+                    Text: "This is the content of the first entry.",
+                },
+            },
+        },
+    }
 
- feedString, err := feed.ToXML("utf-8")
- if err != nil {
-  log.Fatalln(err)
- }
- fmt.Println(feedString)
+    feedString, err := feed.ToXML("UTF-8")
+    if err != nil {
+        log.Fatalln(err)
+    }
+    fmt.Println(feedString)
 }
 ```
 
 The output of both ways of using it is an RFC4287 compliant Atom feed.
 
 ```xml
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="UTF-8"?>
 <feed xmlns="http://www.w3.org/2005/Atom">
-  <author>
-    <name>John Doe</name>
-    <email>john.doe@example.com</email>
-  </author>
-  <id>urn:uuid:60a76c80-d399-11d9-b93C-0003939e0af6</id>
-  <title type="text">Example Feed</title>
-  <updated>2024-10-18T05:49:08+02:00</updated>
-  <entry>
-    <content type="text">This is the content of the first entry.</content>
-    <id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
-    <title type="text">First Entry</title>
-    <updated>2006-01-02T15:04:05+07:00</updated>
-  </entry>
+    <author>
+        <name>John Doe</name>
+        <email>john.doe@example.com</email>
+    </author>
+    <id>urn:uuid:60a76c80-d399-11d9-b93C-0003939e0af6</id>
+    <title type="text">Example Feed</title>
+    <updated>2024-10-18T05:49:08+02:00</updated>
+    <entry>
+        <content type="text">This is the content of the first entry.</content>
+        <id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
+        <title type="text">First Entry</title>
+        <updated>2006-01-02T15:04:05+07:00</updated>
+    </entry>
+</feed>
+```
+
+### Compliance and Error Checking
+
+All Atom constructs have their own ```construct.Check()``` method. It checks for
+compliance with RFC4287 and errors. This allows one to be certain that only
+compliant constructs are added to their respective parent construct. It also
+means that not the entire feed has to be checked every time a new construct is
+added. Instead one only checks the current construct and all of its
+sub-constructs with a single ```construct.Check()``` call.
+
+```go
+package main
+
+import (
+    "fmt"
+    "log"
+
+    "git.streifling.com/jason/atom"
+)
+
+func main() {
+    feed := atom.NewFeed("Example Feed")
+    if err := feed.Check(); err != nil {
+        log.Fatalln(err)
+    }
+
+    entry := atom.NewEntry("One")
+    entry.Content = atom.NewContent(atom.InlineText, "text", "Entry One")
+    entry.AddAuthor(atom.NewPerson("John Doe"))
+    if err := entry.Check(); err != nil {
+        log.Fatalln(err)
+    }
+    feed.AddEntry(entry)
+
+    feedString, err := feed.ToXML("UTF-8")
+    if err != nil {
+        log.Fatalln(err)
+    }
+    fmt.Println(feedString)
+}
+```
+
+### Adding and Deleting Items
+
+To add elements to any slice one calls the appropriate
+```someone.AddSomething(toBeAdded)``` method. It returns the item's index
+number. To delete the item one calls the Delete method.
+
+```go
+package main
+
+import (
+    "fmt"
+    "log"
+
+    "git.streifling.com/jason/atom"
+)
+
+func main() {
+    feed := atom.NewFeed("Feed")
+    if err := feed.Check(); err != nil {
+        log.Fatalln(err)
+    }
+
+    e1 := atom.NewEntry("One")
+    e1.Content = atom.NewContent(atom.InlineText, "text", "Entry One")
+    if err := e1.Check(); err != nil {
+        log.Fatalln(err)
+    }
+    i1 := feed.AddEntry(e1)
+
+    e2 := atom.NewEntry("Two")
+    e2.Content = atom.NewContent(atom.InlineText, "text", "Entry Two")
+    if err := e2.Check(); err != nil {
+        log.Fatalln(err)
+    }
+    feed.AddEntry(e2)
+
+    if err := feed.DeleteEntry(i1); err != nil {
+        log.Fatalln(err)
+    }
+
+    feedString, err := feed.ToXML("UTF-8")
+    if err != nil {
+        log.Fatalln(err)
+    }
+    fmt.Println(feedString)
+}
+```
+
+The output of this example looks like this. It only shows the second entry.
+
+```xml
+<?xml version="1.0" encoding="utf-8"?>
+<feed xmlns="http://www.w3.org/2005/Atom">
+    <id>urn:uuid:ae89d343-b535-447d-ac14-4b80d3e02a2f</id>
+    <title type="text">Example Feed</title>
+    <updated>2024-10-20T14:57:02+02:00</updated>
+    <entry>
+        <content type="text">Entry Two</content>
+        <id>urn:uuid:620c6f73-ee1d-4c1e-be98-b0b1ad7a053f</id>
+        <title type="text">Two</title>
+        <updated>2024-10-20T14:57:02+02:00</updated>
+    </entry>
 </feed>
 ```

atom.go

@@ -16,12 +16,14 @@ type Countable interface {
 	*xml.Attr | *Person | *Category | *Link | *ExtensionElement | *Entry
 }
 
-// addToSlice adds a Countable to to a *[]Countable
-func addToSlice[C Countable](slice *[]C, countable C) {
+// addToSlice adds a Countable to to a *[]Countable. It returns an int.
+func addToSlice[C Countable](slice *[]C, countable C) int {
 	if *slice == nil {
 		*slice = make([]C, 0)
 	}
+
 	*slice = append(*slice, countable)
+	return len(*slice) - 1
 }
 
 // deleteFromSlice deletes the Countable with the index from the *[]Countable.

commonAttributes.go

@@ -17,9 +17,10 @@ func newCommonAttributes() *CommonAttributes {
 	return new(CommonAttributes)
 }
 
-// AddAttribute adds the attribute to the CommonAttributes.
-func (c *CommonAttributes) AddAttribute(name, value string) {
-	addToSlice(&c.UndefinedAttributes, &xml.Attr{Name: xml.Name{Local: name}, Value: value})
+// AddAttribute adds the attribute to the CommonAttributes. It returns its index
+// as an int.
+func (c *CommonAttributes) AddAttribute(name, value string) int {
+	return addToSlice(&c.UndefinedAttributes, &xml.Attr{Name: xml.Name{Local: name}, Value: value})
 }
 
 // DeleteAttribute deletes the attribute at index from the CommonAttributes. It

entry.go

@@ -66,10 +66,11 @@ func NewEntry(title string) *Entry {
 	}
 }
 
-// AddAuthor adds the Person as an author to the Entry.
-func (e *Entry) AddAuthor(p *Person) {
-	addToSlice(&e.Authors, p)
+// AddAuthor adds the Person as an author to the Entry. It returns its index as
+// an int.
+func (e *Entry) AddAuthor(p *Person) int {
 	e.Updated = NewDate(time.Now())
+	return addToSlice(&e.Authors, p)
 }
 
 // DeleteAuthor deletes the Person at index from the Entry. It return an error.
@@ -82,10 +83,10 @@ func (e *Entry) DeleteAuthor(index int) error {
 	return nil
 }
 
-// AddCategory adds the Category to the Entry.
-func (e *Entry) AddCategory(c *Category) {
-	addToSlice(&e.Categories, c)
+// AddCategory adds the Category to the Entry. It returns ts index as an int.
+func (e *Entry) AddCategory(c *Category) int {
 	e.Updated = NewDate(time.Now())
+	return addToSlice(&e.Categories, c)
 }
 
 // DeleteCategory deletes the Category at index from the Entry. It return an
@@ -99,10 +100,11 @@ func (e *Entry) DeleteCategory(index int) error {
 	return nil
 }
 
-// AddContributor adds the Person as a contributor to the Entry.
-func (e *Entry) AddContributor(c *Person) {
-	addToSlice(&e.Contributors, c)
+// AddContributor adds the Person as a contributor to the Entry. It returns its
+// index as an int.
+func (e *Entry) AddContributor(c *Person) int {
 	e.Updated = NewDate(time.Now())
+	return addToSlice(&e.Contributors, c)
 }
 
 // DeleteContributor deletes the Person at index from the Entry. It return an
@@ -116,10 +118,10 @@ func (e *Entry) DeleteContributor(index int) error {
 	return nil
 }
 
-// AddLink adds the Link to the Entry.
-func (e *Entry) AddLink(l *Link) {
-	addToSlice(&e.Links, l)
+// AddLink adds the Link to the Entry. It returns its index as an int.
+func (e *Entry) AddLink(l *Link) int {
 	e.Updated = NewDate(time.Now())
+	return addToSlice(&e.Links, l)
 }
 
 // DeleteLink deletes the Link at index from the Entry. It return an error.
@@ -132,10 +134,11 @@ func (e *Entry) DeleteLink(index int) error {
 	return nil
 }
 
-// AddExtension adds the ExtensionElement to the Entry.
-func (e *Entry) AddExtension(x *ExtensionElement) {
-	addToSlice(&e.Extensions, x)
+// AddExtension adds the ExtensionElement to the Entry. It returns its index as
+// an int.
+func (e *Entry) AddExtension(x *ExtensionElement) int {
 	e.Updated = NewDate(time.Now())
+	return addToSlice(&e.Extensions, x)
 }
 
 // DeleteExtension deletes the Extension at index from the Entry. It return an

feed.go

@@ -35,10 +35,11 @@ func NewFeed(title string) *Feed {
 	}
 }
 
-// AddAuthor adds the Person as an author to the Feed.
-func (f *Feed) AddAuthor(p *Person) {
-	addToSlice(&f.Authors, p)
+// AddAuthor adds the Person as an author to the Feed. It returns its index as
+// an int.
+func (f *Feed) AddAuthor(p *Person) int {
 	f.Updated = NewDate(time.Now())
+	return addToSlice(&f.Authors, p)
 }
 
 // DeleteAuthor deletes the Person at index from the Feed. It return an error.
@@ -51,10 +52,10 @@ func (f *Feed) DeleteAuthor(index int) error {
 	return nil
 }
 
-// AddCategory adds the Category to the Feed.
-func (f *Feed) AddCategory(c *Category) {
-	addToSlice(&f.Categories, c)
+// AddCategory adds the Category to the Feed. It returns its index as an int.
+func (f *Feed) AddCategory(c *Category) int {
 	f.Updated = NewDate(time.Now())
+	return addToSlice(&f.Categories, c)
 }
 
 // DeleteCategory deletes the Category at index from the Feed. It return an
@@ -68,10 +69,11 @@ func (f *Feed) DeleteCategory(index int) error {
 	return nil
 }
 
-// AddContributor adds the Person as a contributor to the Feed.
-func (f *Feed) AddContributor(c *Person) {
-	addToSlice(&f.Contributors, c)
+// AddContributor adds the Person as a contributor to the Feed. It returns its
+// index as an int.
+func (f *Feed) AddContributor(c *Person) int {
 	f.Updated = NewDate(time.Now())
+	return addToSlice(&f.Contributors, c)
 }
 
 // DeleteContributor deletes the Person at index from the Feed. It return an
@@ -86,9 +88,10 @@ func (f *Feed) DeleteContributor(index int) error {
 }
 
 // AddLink adds the Link to the Feed. There should be one Link with Rel "self".
-func (f *Feed) AddLink(l *Link) {
-	addToSlice(&f.Links, l)
+// It returns its index as an int.
+func (f *Feed) AddLink(l *Link) int {
 	f.Updated = NewDate(time.Now())
+	return addToSlice(&f.Links, l)
 }
 
 // DeleteLink deletes the Link at index from the Feed. It return an error.
@@ -101,10 +104,10 @@ func (f *Feed) DeleteLink(index int) error {
 	return nil
 }
 
-// AddExtension adds the Extension to the Feed.
-func (f *Feed) AddExtension(e *ExtensionElement) {
-	addToSlice(&f.Extensions, e)
+// AddExtension adds the Extension to the Feed. It returns its index as an int.
+func (f *Feed) AddExtension(e *ExtensionElement) int {
 	f.Updated = NewDate(time.Now())
+	return addToSlice(&f.Extensions, e)
 }
 
 // DeleteExtension deletes the Extension at index from the Feed. It return an
@@ -118,10 +121,10 @@ func (f *Feed) DeleteExtension(index int) error {
 	return nil
 }
 
-// AddEntry adds the Entry to the Feed.
-func (f *Feed) AddEntry(e *Entry) {
-	addToSlice(&f.Entries, e)
+// AddEntry adds the Entry to the Feed. It returns its index as an int.
+func (f *Feed) AddEntry(e *Entry) int {
 	f.Updated = NewDate(time.Now())
+	return addToSlice(&f.Entries, e)
 }
 
 // DeleteEntry deletes the Entry at index from the Feed. It return an error.

person.go

@@ -21,9 +21,10 @@ func NewPerson(name string) *Person {
 	}
 }
 
-// AddExtension adds the Extension to the Person.
-func (p *Person) AddExtension(e *ExtensionElement) {
-	addToSlice(&p.Extensions, e)
+// AddExtension adds the Extension to the Person. It returns its index as an
+// int.
+func (p *Person) AddExtension(e *ExtensionElement) int {
+	return addToSlice(&p.Extensions, e)
 }
 
 // DeleteExtension deletes the Extension at index from the Person. It return an

source.go

@@ -28,9 +28,10 @@ func NewSource() *Source {
 	return &Source{CommonAttributes: newCommonAttributes()}
 }
 
-// AddAuthor adds the Person as an author to the Source.
-func (s *Source) AddAuthor(p *Person) {
-	addToSlice(&s.Authors, p)
+// AddAuthor adds the Person as an author to the Source. It returns its index as
+// an int.
+func (s *Source) AddAuthor(p *Person) int {
+	return addToSlice(&s.Authors, p)
 }
 
 // DeleteAuthor deletes the Person at index from the Source. It return an error.
@@ -41,9 +42,9 @@ func (s *Source) DeleteAuthor(index int) error {
 	return nil
 }
 
-// AddCategory adds the Category to the Source.
-func (s *Source) AddCategory(c *Category) {
-	addToSlice(&s.Categories, c)
+// AddCategory adds the Category to the Source. It returns its index as an int.
+func (s *Source) AddCategory(c *Category) int {
+	return addToSlice(&s.Categories, c)
 }
 
 // DeleteCategory deletes the Category at index from the Source. It return an
@@ -55,9 +56,10 @@ func (s *Source) DeleteCategory(index int) error {
 	return nil
 }
 
-// AddContributor adds the Person as a contributor to the Source.
-func (s *Source) AddContributor(c *Person) {
-	addToSlice(&s.Contributors, c)
+// AddContributor adds the Person as a contributor to the Source. It returns its
+// index as an int.
+func (s *Source) AddContributor(c *Person) int {
+	return addToSlice(&s.Contributors, c)
 }
 
 // DeleteContributor deletes the Person at index from the Source. It return an
@@ -69,9 +71,9 @@ func (s *Source) DeleteContributor(index int) error {
 	return nil
 }
 
-// AddLink adds the Link to the Source.
-func (s *Source) AddLink(l *Link) {
-	addToSlice(&s.Links, l)
+// AddLink adds the Link to the Source. It returns its index as an int.
+func (s *Source) AddLink(l *Link) int {
+	return addToSlice(&s.Links, l)
 }
 
 // DeleteLink deletes the Link at index from the Source. It return an error.
@@ -82,9 +84,10 @@ func (s *Source) DeleteLink(index int) error {
 	return nil
 }
 
-// AddExtension adds the ExtensionElement to the Source.
-func (s *Source) AddExtension(e *ExtensionElement) {
-	addToSlice(&s.Extensions, e)
+// AddExtension adds the ExtensionElement to the Source. It returns its index as
+// an int.
+func (s *Source) AddExtension(e *ExtensionElement) int {
+	return addToSlice(&s.Extensions, e)
 }
 
 // DeleteExtension deletes the Extension at index from the Source. It return an