Convert Slicer to take constructor options.

Author: Dan Bornstein

README.md

@@ -156,10 +156,9 @@ encodings specified by those. This includes:
 Common Options
 --------------
 
-Some of the classes (as of this writing, most but not all of them)
-take an optional `options` constructor parameter. If not `undefined`,
-this must be a map from option names to values as specified by the
-class.
+All of the classes in this module take an optional `options`
+constructor parameter. If not `undefined`, this must be a map from
+option names to values as specified by the class.
 
 The following are three commonly-accepted options. Classes all accept
 whichever of these make sense.
@@ -517,12 +516,16 @@ The ordering and meaning of the callback arguments are meant to be (a)
 compatible with callbacks used with `fs.read()` and (b) somewhat more
 informative and unambiguous.
 
-### var slicer = new Slicer(source, [incomingEncoding])
+### var slicer = new Slicer(source, [options])
+
+Constructs a new slicer, which listens to the given source.
+
+Of the common options, the only one recognized by this class is
+`incomingEncoding`. The class accepts no other options.
+
+This class recognizes all three of the common options (see above), and
+no others.
 
-Constructs a new slicer, which listens to the given source. The optional
-`incomingEncoding` indicates the initial encoding to use when `data`
-events are received with string payloads (defaults to `undefined`; see
-`setIncomingEncoding()`).
 
 ### slicer.readable => boolean
 
@@ -723,10 +726,7 @@ containing a string payload.
 To Do
 -----
 
-* Use `options` arguments consistently on construction.
-
-* Make `encoding`, `incomingEncoding`, and `paused` all be available
-  as constructor options.
+* Figure out something to do!
 
 
 Contributing

lib/slicer.js

@@ -17,10 +17,21 @@ var typ = require("typ");
 var consts = require("./consts");
 var Codec = require("./codec").Codec;
 var errors = require("./errors");
+var opts = require("./opts");
 var sealer = require("./sealer");
 var sourcesanity = require("./sourcesanity");
 
 
+/*
+ * Module variables
+ */
+
+/** Options spec */
+var OPTIONS = {
+  incomingEncoding: {}
+};
+
+
 /*
  * Helper functions
  */
@@ -152,14 +163,14 @@ Object.freeze(PendingRead.prototype);
 /**
  * Constructs a Slicer state object.
  */
-function State(source, incomingEncoding) {
+function State(source) {
   sourcesanity.validate(source);
 
   /** upstream source (must be stream-like, if not actually a Stream) */
   this.source = source;
 
   /** event receipt encoding handler */
-  this.encoder = new Codec(incomingEncoding);
+  this.encoder = new Codec();
 
   /** queue of pending read operations */
   this.pendingReads = [];
@@ -341,8 +352,10 @@ Object.freeze(State.prototype);
  * `read(..., callback)` interface for consuming the so-collected
  * data.
  */
-function Slicer(source, incomingEncoding) {
-  this.slicer = sealer.seal(new State(source, incomingEncoding));
+function Slicer(source, options) {
+  options = opts.validate(options, OPTIONS);
+  this.slicer = sealer.seal(new State(source));
+  opts.handleCommon(options, this);
 }
 
 /**

test/slicer.js

@@ -23,8 +23,11 @@ var emit = require("./emit").emit;
  * Makes sure the constructor doesn't fail off the bat.
  */
 function constructor() {
-  new Slicer(new events.EventEmitter());
-  new Slicer(new events.EventEmitter(), "hex");
+  var emitter = new events.EventEmitter();
+
+  new Slicer(emitter);
+  new Slicer(emitter, {});
+  new Slicer(emitter, { incomingEncoding: "hex" });
 }
 
 /**
@@ -42,9 +45,14 @@ function constructorFailures() {
   assert.throws(f2, /Source not an EventEmitter/);
 
   function f3() {
-    new Slicer(new events.EventEmitter(), "bad-encoding");
+    new Slicer(new events.EventEmitter(), { incomingEncoding: "bad-encoding" });
+  }
+  assert.throws(f3, /Bad value for option: incomingEncoding/);
+
+  function f4() {
+    new Slicer(new events.EventEmitter(), { frobnitz: "fizmo" });
   }
-  assert.throws(f3, /Invalid encoding name/);
+  assert.throws(f4, /Unknown option: frobnitz/);
 }
 
 /**
@@ -480,7 +488,7 @@ function constructorEncodings() {
 
   function tryWith(encodingName, dataString) {
     var source = new events.EventEmitter();
-    var slicer = new Slicer(source, encodingName);
+    var slicer = new Slicer(source, { incomingEncoding: encodingName });
     var coll = new CallbackCollector();
 
     if (encodingName === "utf16le") {