Use process warnings for deprecations

lib/Client.js

@@ -4,6 +4,7 @@ const Base = require("./structures/Base");
 const Channel = require("./structures/Channel");
 const Collection = require("./util/Collection");
 const Constants = require("./Constants");
+const emitDeprecation = require("./util/emitDeprecation");
 const Endpoints = require("./rest/Endpoints");
 const ExtendedUser = require("./structures/ExtendedUser");
 const GroupChannel = require("./structures/GroupChannel");
@@ -286,6 +287,7 @@ class Client extends EventEmitter {
     */
     addMessageReaction(channelID, messageID, reaction, userID) {
         if(userID !== undefined) {
+            emitDeprecation("eris:1", "addMessageReaction() was called without an \"@me\" `userID` argument");
             this.emit("warn", "[DEPRECATED] addMessageReaction() was called without an \"@me\" `userID` argument");
         }
         if(reaction === decodeURI(reaction)) {
@@ -418,12 +420,14 @@ class Client extends EventEmitter {
     */
     createChannel(guildID, name, type, reason, options = {}) {
         if(typeof options === "string") { // This used to be parentID, back-compat
+            emitDeprecation("eris:2", "createChannel() was called with a string `options` argument");
             this.emit("warn", "[DEPRECATED] createChannel() was called with a string `options` argument");
             options = {
                 parentID: options
             };
         }
         if(typeof reason === "string") { // Reason is deprecated, will be folded into options
+            emitDeprecation("eris:3", "createChannel() was called with a string `reason` argument");
             this.emit("warn", "[DEPRECATED] createChannel() was called with a string `reason` argument");
             options.reason = reason;
             reason = undefined;
@@ -623,6 +627,7 @@ class Client extends EventEmitter {
             } else if(content.content !== undefined && typeof content.content !== "string") {
                 content.content = "" + content.content;
             } else if(content.embed && !content.embeds) {
+                emitDeprecation("eris:4", "content.embed is deprecated. Use content.embeds instead");
                 this.emit("warn", "[DEPRECATED] content.embed is deprecated. Use content.embeds instead");
                 content.embeds = [content.embed];
             }
@@ -647,6 +652,7 @@ class Client extends EventEmitter {
                     content.messageReference.failIfNotExists = undefined;
                 }
             } else if(content.messageReferenceID) {
+                emitDeprecation("eris:5", "content.messageReferenceID is deprecated. Use content.messageReference instead");
                 this.emit("warn", "[DEPRECATED] content.messageReferenceID is deprecated. Use content.messageReference instead");
                 content.message_reference = {message_id: content.messageReferenceID};
             }
@@ -1280,6 +1286,7 @@ class Client extends EventEmitter {
             } else if(content.content !== undefined && typeof content.content !== "string") {
                 content.content = "" + content.content;
             } else if(content.embed && !content.embeds) {
+                emitDeprecation("eris:6", "content.embed is deprecated. Use content.embeds instead");
                 this.emit("warn", "[DEPRECATED] content.embed is deprecated. Use content.embeds instead");
                 content.embeds = [content.embed];
             }
@@ -1968,6 +1975,7 @@ class Client extends EventEmitter {
             options.after = after;
         }
         if(options.before) {
+            emitDeprecation("eris:7", "getMessageReaction() was called with a `before` parameter. Discord no longer supports this parameter");
             this.emit("warn", "[DEPRECATED] getMessageReaction() was called with a `before` parameter. Discord no longer supports this parameter");
         }
         return this.requestHandler.request("GET", Endpoints.CHANNEL_MESSAGE_REACTION(channelID, messageID, reaction), true, options).then((users) => users.map((user) => new User(user, this)));

lib/structures/Member.js

@@ -1,6 +1,7 @@
 "use strict";
 
 const Base = require("./Base");
+const emitDeprecation = require("../util/emitDeprecation");
 const Endpoints = require("../rest/Endpoints");
 const User = require("./User");
 const VoiceState = require("./VoiceState");
@@ -133,6 +134,7 @@ class Member extends Base {
     }
 
     get permission() {
+        emitDeprecation("eris:8", "Member#permission is deprecated. Use Member#permissions instead");
         this.guild.shard.client.emit("warn", "[DEPRECATED] Member#permission is deprecated. Use Member#permissions instead");
         return this.permissions;
     }

lib/structures/PrivateChannel.js

@@ -2,6 +2,7 @@
 
 const Channel = require("./Channel");
 const Collection = require("../util/Collection");
+const emitDeprecation = require("../util/emitDeprecation");
 const Endpoints = require("../rest/Endpoints");
 const Message = require("./Message");
 const {GatewayOPCodes, ChannelTypes} = require("../Constants");
@@ -203,6 +204,7 @@ class PrivateChannel extends Channel {
     */
     removeMessageReaction(messageID, reaction, userID) {
         if(userID !== undefined) {
+            emitDeprecation("eris:9", "removeMessageReaction() was called on a PrivateChannel with a `userID` argument");
             this.emit("warn", "[DEPRECATED] removeMessageReaction() was called on a PrivateChannel with a `userID` argument");
         }
         return this.client.removeMessageReaction.call(this.client, this.id, messageID, reaction, userID);

lib/util/emitDeprecation.js

@@ -0,0 +1,9 @@
+const emittedCodes = new Set();
+
+module.exports = function emitDeprecation(code, description) {
+    if(emittedCodes.has(code) ) {
+        return;
+    }
+    emittedCodes.add(code);
+    process.emitWarning(description, "DeprecationWarning", code);
+};