Made error constants (Fixed #315) (#377)

restapi.go

@@ -29,8 +29,15 @@ import (
 	"time"
 )
 
-// ErrJSONUnmarshal is returned for JSON Unmarshall errors.
+// All error constants
-var ErrJSONUnmarshal = errors.New("json unmarshal")
+var (
+	ErrJSONUnmarshal           = errors.New("json unmarshal")
+	ErrStatusOffline           = errors.New("You can't set your Status to offline")
+	ErrVerificationLevelBounds = errors.New("VerificationLevel out of bounds, should be between 0 and 3")
+	ErrPruneDaysBounds         = errors.New("the number of days should be more than or equal to 1")
+	ErrGuildNoIcon             = errors.New("guild does not have an icon set")
+	ErrGuildNoSplash           = errors.New("guild does not have a splash set")
+)
 
 // Request is the same as RequestWithBucketID but the bucket id is the same as the urlStr
 func (s *Session) Request(method, urlStr string, data interface{}) (response []byte, err error) {
@@ -334,7 +341,7 @@ func (s *Session) UserSettings() (st *Settings, err error) {
 // status   : The new status (Actual valid status are 'online','idle','dnd','invisible')
 func (s *Session) UserUpdateStatus(status Status) (st *Settings, err error) {
 	if status == StatusOffline {
-		err = errors.New("You can't set your Status to offline")
+		err = ErrStatusOffline
 		return
 	}
 
@@ -595,7 +602,7 @@ func (s *Session) GuildEdit(guildID string, g GuildParams) (st *Guild, err error
 	if g.VerificationLevel != nil {
 		val := *g.VerificationLevel
 		if val < 0 || val > 3 {
-			err = errors.New("VerificationLevel out of bounds, should be between 0 and 3")
+			err = ErrVerificationLevelBounds
 			return
 		}
 	}
@@ -988,7 +995,7 @@ func (s *Session) GuildPruneCount(guildID string, days uint32) (count uint32, er
 	count = 0
 
 	if days <= 0 {
-		err = errors.New("the number of days should be more than or equal to 1")
+		err = ErrPruneDaysBounds
 		return
 	}
 
@@ -1018,7 +1025,7 @@ func (s *Session) GuildPrune(guildID string, days uint32) (count uint32, err err
 	count = 0
 
 	if days <= 0 {
-		err = errors.New("the number of days should be more than or equal to 1")
+		err = ErrPruneDaysBounds
 		return
 	}
 
@@ -1120,7 +1127,7 @@ func (s *Session) GuildIcon(guildID string) (img image.Image, err error) {
 	}
 
 	if g.Icon == "" {
-		err = errors.New("guild does not have an icon set")
+		err = ErrGuildNoIcon
 		return
 	}
 
@@ -1142,7 +1149,7 @@ func (s *Session) GuildSplash(guildID string) (img image.Image, err error) {
 	}
 
 	if g.Splash == "" {
-		err = errors.New("guild does not have a splash set")
+		err = ErrGuildNoSplash
 		return
 	}
 

state.go

@@ -21,6 +21,10 @@ import (
 // ErrNilState is returned when the state is nil.
 var ErrNilState = errors.New("state not instantiated, please use discordgo.New() or assign Session.State")
 
+// ErrStateNotFound is returned when the state cache
+// requested is not found
+var ErrStateNotFound = errors.New("state cache not found")
+
 // A State contains the current known state.
 // As discord sends this in a READY blob, it seems reasonable to simply
 // use that struct as the data store.
@@ -146,7 +150,7 @@ func (s *State) Guild(guildID string) (*Guild, error) {
 		return g, nil
 	}
 
-	return nil, errors.New("guild not found")
+	return nil, ErrStateNotFound
 }
 
 // PresenceAdd adds a presence to the current world state, or
@@ -227,7 +231,7 @@ func (s *State) PresenceRemove(guildID string, presence *Presence) error {
 		}
 	}
 
-	return errors.New("presence not found")
+	return ErrStateNotFound
 }
 
 // Presence gets a presence by ID from a guild.
@@ -247,7 +251,7 @@ func (s *State) Presence(guildID, userID string) (*Presence, error) {
 		}
 	}
 
-	return nil, errors.New("presence not found")
+	return nil, ErrStateNotFound
 }
 
 // TODO: Consider moving Guild state update methods onto *Guild.
@@ -299,7 +303,7 @@ func (s *State) MemberRemove(member *Member) error {
 		}
 	}
 
-	return errors.New("member not found")
+	return ErrStateNotFound
 }
 
 // Member gets a member by ID from a guild.
@@ -322,7 +326,7 @@ func (s *State) Member(guildID, userID string) (*Member, error) {
 		}
 	}
 
-	return nil, errors.New("member not found")
+	return nil, ErrStateNotFound
 }
 
 // RoleAdd adds a role to the current world state, or
@@ -372,7 +376,7 @@ func (s *State) RoleRemove(guildID, roleID string) error {
 		}
 	}
 
-	return errors.New("role not found")
+	return ErrStateNotFound
 }
 
 // Role gets a role by ID from a guild.
@@ -395,7 +399,7 @@ func (s *State) Role(guildID, roleID string) (*Role, error) {
 		}
 	}
 
-	return nil, errors.New("role not found")
+	return nil, ErrStateNotFound
 }
 
 // ChannelAdd adds a channel to the current world state, or
@@ -428,7 +432,7 @@ func (s *State) ChannelAdd(channel *Channel) error {
 	} else {
 		guild, ok := s.guildMap[channel.GuildID]
 		if !ok {
-			return errors.New("guild for channel not found")
+			return ErrStateNotFound
 		}
 
 		guild.Channels = append(guild.Channels, channel)
@@ -507,7 +511,7 @@ func (s *State) Channel(channelID string) (*Channel, error) {
 		return c, nil
 	}
 
-	return nil, errors.New("channel not found")
+	return nil, ErrStateNotFound
 }
 
 // Emoji returns an emoji for a guild and emoji id.
@@ -530,7 +534,7 @@ func (s *State) Emoji(guildID, emojiID string) (*Emoji, error) {
 		}
 	}
 
-	return nil, errors.New("emoji not found")
+	return nil, ErrStateNotFound
 }
 
 // EmojiAdd adds an emoji to the current world state.
@@ -647,7 +651,7 @@ func (s *State) messageRemoveByID(channelID, messageID string) error {
 		}
 	}
 
-	return errors.New("message not found")
+	return ErrStateNotFound
 }
 
 func (s *State) voiceStateUpdate(update *VoiceStateUpdate) error {
@@ -701,7 +705,7 @@ func (s *State) Message(channelID, messageID string) (*Message, error) {
 		}
 	}
 
-	return nil, errors.New("message not found")
+	return nil, ErrStateNotFound
 }
 
 // OnReady takes a Ready event and updates all internal state.

wsapi.go

@@ -25,6 +25,18 @@ import (
 	"github.com/gorilla/websocket"
 )
 
+// ErrWSAlreadyOpen is thrown when you attempt to open
+// a websocket that already is open.
+var ErrWSAlreadyOpen = errors.New("web socket already opened")
+
+// ErrWSNotFound is thrown when you attempt to use a websocket
+// that doesn't exist
+var ErrWSNotFound = errors.New("no websocket connection exists")
+
+// ErrWSShardBounds is thrown when you try to use a shard ID that is
+// less than the total shard count
+var ErrWSShardBounds = errors.New("ShardID must be less than ShardCount")
+
 type resumePacket struct {
 	Op   int `json:"op"`
 	Data struct {
@@ -58,7 +70,7 @@ func (s *Session) Open() (err error) {
 	}
 
 	if s.wsConn != nil {
-		err = errors.New("web socket already opened")
+		err = ErrWSAlreadyOpen
 		return
 	}
 
@@ -250,7 +262,7 @@ func (s *Session) UpdateStreamingStatus(idle int, game string, url string) (err
 	s.RLock()
 	defer s.RUnlock()
 	if s.wsConn == nil {
-		return errors.New("no websocket connection exists")
+		return ErrWSNotFound
 	}
 
 	var usd updateStatusData
@@ -307,7 +319,7 @@ func (s *Session) RequestGuildMembers(guildID, query string, limit int) (err err
 	s.RLock()
 	defer s.RUnlock()
 	if s.wsConn == nil {
-		return errors.New("no websocket connection exists")
+		return ErrWSNotFound
 	}
 
 	data := requestGuildMembersData{
@@ -621,7 +633,7 @@ func (s *Session) identify() error {
 	if s.ShardCount > 1 {
 
 		if s.ShardID >= s.ShardCount {
-			return errors.New("ShardID must be less than ShardCount")
+			return ErrWSShardBounds
 		}
 
 		data.Shard = &[2]int{s.ShardID, s.ShardCount}