value: Convert from a getter to a method.

doc/API.md

@@ -6,7 +6,7 @@
   - [writeOnly() -> Channel](#writeonly---channel)
   - [Channel.select(promises) -> async channel](#channelselectpromises---async-channel)
     - [Examples](#examples)
-  - [value](#value)
+  - [value()](#value)
 - [Array-like Properties](#array-like-properties)
   - [Channel](#channel)
     - [Channel([bufferLength = 0]) -> Channel](#channelbufferlength--0---channel)
@@ -71,11 +71,11 @@ switch (await Channel.select([
   charlie.push(`Hi!`)
 ])) {
   case alice:
-    console.log(`Alice said ${alice.value}.`);
+    console.log(`Alice said ${alice.value()}.`);
     break;
 
   case bob:
-    console.log(`Bob said ${bob.value}.`);
+    console.log(`Bob said ${bob.value()}.`);
     break;
 
   case charlie:
@@ -108,11 +108,11 @@ closed.close();
 
 switch (await Channel.select([alice.shift(), bob.shift(), closed.shift())]) {
   case alice:
-    console.log(`Alice said ${alice.value}.`);
+    console.log(`Alice said ${alice.value()}.`);
     break;
 
   case bob:
-    console.log(`Bob said ${bob.value}.`);
+    console.log(`Bob said ${bob.value()}.`);
     break;
 
   default:
@@ -128,11 +128,11 @@ setTimeout(timeout.close, 1000);
 
 switch (await Channel.select([alice.shift(), bob.shift(), timeout.shift())]) {
   case alice:
-    console.log(`Alice said ${alice.value}.`);
+    console.log(`Alice said ${alice.value()}.`);
     break;
 
   case bob:
-    console.log(`Bob said ${bob.value}.`);
+    console.log(`Bob said ${bob.value()}.`);
     break;
 
   default:
@@ -140,9 +140,9 @@ switch (await Channel.select([alice.shift(), bob.shift(), timeout.shift())]) {
 }
 ```
 
-## value
+## value()
 
-Set to the most recently `shift`ed value.  This is useful when used in
+Return the most recently `shift`ed value.  This is useful when used in
 combination with `select`.
 
 # Array-like Properties

lib/index.js

@@ -36,7 +36,7 @@ const Order = channel => {
 
 const prototype = {};
 
-const Channel = function(bufferLength = 0) {
+const Channel = function(length = 0) {
   let buffered = 0;
   let closed = false;
   let lastValue;
@@ -70,7 +70,7 @@ const Channel = function(bufferLength = 0) {
     for (
       ;
       resolvedIndex < index.push ||
-      (resolvedIndex < pushes.length && buffered < bufferLength);
+      (resolvedIndex < pushes.length && buffered < length);
       resolvedIndex++
     ) {
       const { cancelled, resolve } = pushes[resolvedIndex];
@@ -80,7 +80,7 @@ const Channel = function(bufferLength = 0) {
           buffered++;
         }
 
-        resolve(bufferLength);
+        resolve(length);
       }
     }
 
@@ -101,7 +101,8 @@ const Channel = function(bufferLength = 0) {
     resolvedIndex -= index.push;
   };
 
-  const readOnly = Object.assign(Object.create(prototype), {
+  const readOnly = Object.freeze(
+    Object.assign(Object.create(prototype), {
       every: async (callbackfn, thisArg) => {
         for (;;) {
           const value = await readOnly.shift();
@@ -241,7 +242,9 @@ const Channel = function(bufferLength = 0) {
         }
       },
 
-    toString: () => `Channel(${bufferLength})`,
+      toString: () => `Channel(${length})`,
+
+      value: () => lastValue,
 
       values: async () => {
         const array = [];
@@ -252,16 +255,11 @@ const Channel = function(bufferLength = 0) {
 
         return array;
       }
-  });
+    })
+  );
 
-  Object.defineProperties(readOnly, {
-    length: { get: () => bufferLength },
-    value: { get: () => lastValue }
-  });
-
-  Object.freeze(readOnly);
-
-  const writeOnly = Object.freeze({
+  const writeOnly = Object.freeze(
+    Object.assign(Object.create(prototype), {
       close: () =>
         new Promise((resolve, reject) => {
           if (closed) {
@@ -275,6 +273,8 @@ const Channel = function(bufferLength = 0) {
           }
         }),
 
+      length,
+
       push: function(value) {
         const { order, promise } = Order(this);
         order.value = value;
@@ -283,7 +283,9 @@ const Channel = function(bufferLength = 0) {
           order.reject(new Error(`Can't push to closed channel.`));
         } else if (value === undefined) {
           order.reject(
-          new TypeError(`Can't push 'undefined' to channel, use close instead.`)
+            new TypeError(
+              `Can't push 'undefined' to channel, use close instead.`
+            )
           );
         } else if (arguments.length > 1) {
           order.reject(new Error(`Can't push more than one value at a time.`));
@@ -296,10 +298,12 @@ const Channel = function(bufferLength = 0) {
       },
 
       writeOnly: () => writeOnly
-  });
+    })
+  );
 
-  // Use Object.create because readOnly has a getter.
-  return Object.freeze(Object.assign(Object.create(readOnly), writeOnly));
+  return Object.freeze(
+    Object.assign(Object.create(prototype), readOnly, writeOnly)
+  );
 };
 
 Channel.from = values => {
@@ -384,7 +388,10 @@ Channel.select = methodPromises =>
 // Channel.slice(10)(Infinity)(channel)
 
 const channel = Channel();
-const methods = Object.keys(channel).concat(Object.keys(channel.readOnly()));
+
+const methods = Object.keys(channel).filter(
+  method => typeof channel[method] === `function`
+);
 
 methods.forEach(method => {
   const bound = function(...args) {

test/index.js

@@ -63,6 +63,8 @@ describe(`Channel`, function() {
   it(`isChannel`, function() {
     assert(Channel.isChannel(Channel.of(0, 1, 2)));
     assert(!Channel.isChannel(Array.of(0, 1, 2)));
+    assert(Channel.isChannel(Channel().readOnly()));
+    assert(Channel.isChannel(Channel().writeOnly()));
   });
 
   it(`of`, async function() {
@@ -80,7 +82,7 @@ describe(`Channel`, function() {
       })();
 
       assert.equal(await Channel.select([a.shift(), b.shift()]), b);
-      assert.equal(b.value, 0);
+      assert.equal(b.value(), 0);
       assert.equal(await a.shift(), 1);
       assert.equal(await Channel.select([a.push(0), b.shift()]), a);
     });
@@ -294,7 +296,7 @@ describe(`Channel object`, function() {
 
     assert.equal(readOnly.readOnly(), readOnly);
     assert.equal(await readOnly.shift(), 1);
-    assert.equal(readOnly.value, 1);
+    assert.equal(readOnly.value(), 1);
 
     assert.throws(() => {
       readOnly.frozen = false;
@@ -367,21 +369,13 @@ describe(`Channel object`, function() {
   });
 
   it(`value`, async function() {
-    const channel = Channel();
-    (async () => {
-      await channel.push(0);
-    })();
-
+    const channel = Channel(1);
+    await channel.push(null);
     await channel.shift();
-    assert.equal(channel.value, 0);
-
-    assert.throws(() => {
-      channel.value = 1;
-    });
-
+    assert.equal(channel.value(), null);
     channel.close();
     await channel.shift();
-    assert.equal(channel.value, undefined);
+    assert.equal(channel.value(), undefined);
   });
 
   it(`values`, async function() {