Use less return_val_if_fail checks

In C, we often check preconditions in our functions using
`g_return_if_fail()` or `g_return_val_fail()`, which are macros that
expand to the condition they're checking for so the logs clearly show
what might be going wrong.

Vala also exposes these functions, but given that Vala compiles to a lot
of jibberish temp variables, the output is not quite vague. Try to use
the Vala equivalent `requires` to do something similar (unfortunately,
we can't use this everywhere as it can only be used at the beginning of
a mehod).

4 files changed, 38 insertions, 39 deletions

diff --git a/src/contacts-contact-pane.vala b/src/contacts-contact-pane.vala
index ee9ee6c..48f5aac 100644
--- a/src/contacts-contact-pane.vala
+++ b/src/contacts-contact-pane.vala
@@ -90,9 +90,8 @@ public class Contacts.ContactPane : Adw.Bin {
     show_contact_sheet (this.contact);
   }
 
-  private void show_contact_sheet (Contact contact) {
-    return_if_fail (contact != null);
-
+  private void show_contact_sheet (Contact contact)
+      requires (this.contact != null) {
     remove_contact_sheet ();
     var contacts_sheet = new ContactSheet (contact);
     contacts_sheet.hexpand = true;
@@ -123,8 +122,8 @@ public class Contacts.ContactPane : Adw.Bin {
     this.sheet = null;
   }
 
-  private void create_contact_editor () {
-    return_if_fail (this.contact != null);
+  private void create_contact_editor ()
+      requires (this.contact != null) {
 
     remove_contact_editor ();
     var contact_editor = new ContactEditor (this.contact);
@@ -142,8 +141,8 @@ public class Contacts.ContactPane : Adw.Bin {
     this.editor = null;
   }
 
-  public void stop_editing (bool cancel = false) {
-    return_if_fail (this.on_edit_mode);
+  public void stop_editing (bool cancel = false)
+      requires (this.on_edit_mode) {
 
     this.on_edit_mode = false;
     remove_contact_editor ();
@@ -196,8 +195,8 @@ public class Contacts.ContactPane : Adw.Bin {
     }
   }
 
-  public void edit_contact () {
-    return_if_fail (this.contact != null);
+  public void edit_contact ()
+      requires (this.contact != null) {
     if (this.on_edit_mode)
       return;
 
diff --git a/src/contacts-contact-sheet.vala b/src/contacts-contact-sheet.vala
index b604bdc..550b19f 100644
--- a/src/contacts-contact-sheet.vala
+++ b/src/contacts-contact-sheet.vala
@@ -177,9 +177,9 @@ public class Contacts.ContactSheet : Gtk.Widget {
     return header;
   }
 
-  private Gtk.Widget create_widget_for_roles (Chunk chunk) {
-    unowned var roles_chunk = chunk as RolesChunk;
-    return_if_fail (roles_chunk != null);
+  private Gtk.Widget create_widget_for_roles (Chunk chunk)
+      requires (chunk is RolesChunk) {
+    unowned var roles_chunk = (RolesChunk) chunk;
 
     var group = new ContactSheetGroup ();
 
@@ -197,9 +197,9 @@ public class Contacts.ContactSheet : Gtk.Widget {
     return group;
   }
 
-  private Gtk.Widget create_widget_for_emails (Chunk chunk) {
-    unowned var emails_chunk = chunk as EmailAddressesChunk;
-    return_if_fail (emails_chunk != null);
+  private Gtk.Widget create_widget_for_emails (Chunk chunk)
+      requires (chunk is EmailAddressesChunk) {
+    unowned var emails_chunk = (EmailAddressesChunk) chunk;
 
     var group = new ContactSheetGroup ();
 
@@ -225,9 +225,9 @@ public class Contacts.ContactSheet : Gtk.Widget {
     return group;
   }
 
-  private Gtk.Widget create_widget_for_phone_nrs (Chunk chunk) {
-    unowned var phones_chunk = chunk as PhonesChunk;
-    return_if_fail (phones_chunk != null);
+  private Gtk.Widget create_widget_for_phone_nrs (Chunk chunk)
+      requires (chunk is PhonesChunk) {
+    unowned var phones_chunk = (PhonesChunk) chunk;
 
     var group = new ContactSheetGroup ();
 
@@ -245,13 +245,13 @@ public class Contacts.ContactSheet : Gtk.Widget {
     return group;
   }
 
-  private Gtk.Widget? create_widget_for_im_addresses (Chunk chunk) {
+  private Gtk.Widget? create_widget_for_im_addresses (Chunk chunk)
+      requires (chunk is ImAddressesChunk) {
     // NOTE: We _could_ enable this again, but only for specific services.
     // Right now, this just enables a million "Windows Live Messenger" and
     // "Jabber", ... fields, which are all resting in their respective coffins.
 #if 0
-    unowned var im_addrs_chunk = chunk as ImAddressesChunk;
-    return_if_fail (im_addrs_chunk != null);
+    unowned var im_addrs_chunk = (ImAddressesChunk) chunk;
 
     var group = new ContactSheetGroup ();
 
@@ -272,9 +272,9 @@ public class Contacts.ContactSheet : Gtk.Widget {
     return null;
   }
 
-  private Gtk.Widget create_widget_for_urls (Chunk chunk) {
-    unowned var urls_chunk = chunk as UrlsChunk;
-    return_if_fail (urls_chunk != null);
+  private Gtk.Widget create_widget_for_urls (Chunk chunk)
+      requires (chunk is UrlsChunk) {
+    unowned var urls_chunk = (UrlsChunk) chunk;
 
     var group = new ContactSheetGroup ();
 
@@ -301,17 +301,17 @@ public class Contacts.ContactSheet : Gtk.Widget {
     return group;
   }
 
-  private Gtk.Widget create_widget_for_nickname (Chunk chunk) {
-    unowned var nickname_chunk = chunk as NicknameChunk;
-    return_if_fail (nickname_chunk != null || nickname_chunk.nickname != null);
+  private Gtk.Widget create_widget_for_nickname (Chunk chunk)
+      requires (chunk is NicknameChunk) {
+    unowned var nickname_chunk = (NicknameChunk) chunk;
 
     var row = new ContactSheetRow (chunk.property_name, nickname_chunk.nickname);
     return new ContactSheetGroup.single_row (row);
   }
 
-  private Gtk.Widget create_widget_for_birthday (Chunk chunk) {
-    unowned var birthday_chunk = chunk as BirthdayChunk;
-    return_if_fail (birthday_chunk != null || birthday_chunk.birthday != null);
+  private Gtk.Widget create_widget_for_birthday (Chunk chunk)
+      requires (chunk is BirthdayChunk) {
+    unowned var birthday_chunk = (BirthdayChunk) chunk;
 
     var birthday_str = birthday_chunk.birthday.to_local ().format ("%x");
 
@@ -326,9 +326,9 @@ public class Contacts.ContactSheet : Gtk.Widget {
     return new ContactSheetGroup.single_row (row);
   }
 
-  private Gtk.Widget create_widget_for_notes (Chunk chunk) {
-    unowned var notes_chunk = chunk as NotesChunk;
-    return_if_fail (notes_chunk != null);
+  private Gtk.Widget create_widget_for_notes (Chunk chunk)
+      requires (chunk is NotesChunk) {
+    unowned var notes_chunk = (NotesChunk) chunk;
 
     var group = new ContactSheetGroup ();
 
@@ -344,9 +344,9 @@ public class Contacts.ContactSheet : Gtk.Widget {
     return group;
   }
 
-  private Gtk.Widget create_widget_for_postal_addresses (Chunk chunk) {
-    unowned var addresses_chunk = chunk as AddressesChunk;
-    return_if_fail (addresses_chunk != null);
+  private Gtk.Widget create_widget_for_postal_addresses (Chunk chunk)
+      requires (chunk is AddressesChunk) {
+    unowned var addresses_chunk = (AddressesChunk) chunk;
 
     // Check outside of the loop if we have a "maps:" URI handler
     var appinfo = AppInfo.get_default_for_uri_scheme ("maps");
diff --git a/src/core/contacts-bin-chunk.vala b/src/core/contacts-bin-chunk.vala
index eac0060..cfaba43 100644
--- a/src/core/contacts-bin-chunk.vala
+++ b/src/core/contacts-bin-chunk.vala
@@ -49,7 +49,7 @@ public abstract class Contacts.BinChunk : Chunk, GLib.ListModel {
   public override bool dirty {
     get {
       // If we're hitting this, a subclass forgot to set the field
-      return_if_fail (this.original_elements_set);
+      return_val_if_fail (this.original_elements_set, false);
 
       var non_empty_count = nr_nonempty_children ();
       if (this.original_elements.length != non_empty_count)
diff --git a/src/io/contacts-io.vala b/src/io/contacts-io.vala
index 743a38c..094298d 100644
--- a/src/io/contacts-io.vala
+++ b/src/io/contacts-io.vala
@@ -79,8 +79,8 @@ namespace Contacts.Io {
   /**
    * Deserializes the {@link GLib.Variant} back into a {@link GLib.HashTable}.
    */
-  public HashTable<string, Value?>[] deserialize_gvariant (GLib.Variant variant) {
-    return_val_if_fail (variant.get_type ().equal (new VariantType ("aa{sv}")), null);
+  public HashTable<string, Value?>[] deserialize_gvariant (GLib.Variant variant)
+      requires (variant.get_type ().equal (new VariantType ("aa{sv}"))) {
 
     var result = new GenericArray<HashTable<string, Value?>> ();