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Documenting and testing 'do'

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This commit is contained in:
Jeremy Ashkenas
2010-12-24 09:22:27 -08:00
parent 094b876a38
commit 3be22bd43b
8 changed files with 45 additions and 56 deletions
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4
documentation/coffee/do.coffee Normal file
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@@ -0,0 +1,4 @@
for fileName in list
do (fileName) ->
fs.readFile fileName, (err, contents) ->
compile fileName, contents.toString()

4
documentation/coffee/scoped_loops.coffee
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@@ -1,4 +0,0 @@
funcs = []
for i in [0..3] ->
funcs.push (number) -> number + i

11
documentation/index.html.erb
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@@ -530,13 +530,12 @@ Expressions
<tt>for own key, value of object</tt>
</p>
<p>
In JavaScript, it's extremely common to run into trouble when trying to
generate functions within a loop &mdash; all of the created functions share
the final value of loop variables. CoffeeScript provides a "scoped loop"
syntax for loops that should have function scope, similar to a <tt>forEach</tt>.
Note how the body of the loop gets lifted into a cached function.
When using a JavaScript loop to generate functions, it's common to insert
a closure wrapper in order to ensure that loop variables are closed over,
and all the generated functions don't just share the final values. CoffeeScript
provides the <tt>do</tt> keyword, which immediately invokes a passed function.
</p>
<%= code_for('scoped_loops', 'funcs[3](2)') %>
<%= code_for('do') %>
<p>
<span id="slices" class="bookmark"></span>

10
documentation/js/do.js Normal file
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@@ -0,0 +1,10 @@
var fileName, _fn, _i, _len;
_fn = function(fileName) {
return fs.readFile(fileName, function(err, contents) {
return compile(fileName, contents.toString());
});
};
for (_i = 0, _len = list.length; _i < _len; _i++) {
fileName = list[_i];
_fn(fileName);
}

10
documentation/js/scoped_loops.js
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@@ -1,10 +0,0 @@
var funcs, i, _fn;
funcs = [];
_fn = function(i) {
funcs.push(function(number) {
return number + i;
});
};
for (i = 0; i <= 3; i++) {
_fn(i);
}

4
documentation/js/splices.js
View File

@@ -1,3 +1,3 @@
var numbers;
var numbers, _ref;
numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
[].splice.apply(numbers, [3, 4].concat([-3, -4, -5, -6]));
[].splice.apply(numbers, [3, 4].concat(_ref = [-3, -4, -5, -6])), _ref;

50
index.html
View File

@@ -908,36 +908,26 @@ ages = (function() {
<tt>for own key, value of object</tt>
</p>
<p>
In JavaScript, it's extremely common to run into trouble when trying to
generate functions within a loop &mdash; all of the created functions share
the final value of loop variables. CoffeeScript provides a "scoped loop"
syntax for loops that should have function scope, similar to a <tt>forEach</tt>.
Note how the body of the loop gets lifted into a cached function.
When using a JavaScript loop to generate functions, it's common to insert
a closure wrapper in order to ensure that loop variables are closed over,
and all the generated functions don't just share the final values. CoffeeScript
provides the <tt>do</tt> keyword, which immediately invokes a passed function.
</p>
<div class='code'><pre class="idle">funcs <span class="Keyword">=</span> []
<span class="Keyword">for</span> i <span class="Keyword">in</span> [<span class="Number">0</span>..<span class="Number">3</span>] <span class="Keyword">-</span><span class="Keyword">&gt;</span>
funcs.push <span class="FunctionArgument">(number)</span> <span class="Storage">-&gt;</span> number <span class="Keyword">+</span> i
</pre><pre class="idle"><span class="Storage">var</span> funcs, i, _fn;
funcs <span class="Keyword">=</span> [];
<span class="FunctionName">_fn</span> = <span class="Storage">function</span>(<span class="FunctionArgument">i</span>) {
funcs.<span class="LibraryFunction">push</span>(<span class="Storage">function</span>(number) {
<span class="Keyword">return</span> number <span class="Keyword">+</span> i;
<div class='code'><pre class="idle"><span class="Keyword">for</span> fileName <span class="Keyword">in</span> list
do <span class="FunctionArgument">(fileName)</span> <span class="Storage">-&gt;</span>
fs.readFile fileName, <span class="FunctionArgument">(err, contents)</span> <span class="Storage">-&gt;</span>
compile fileName, contents.toString()
</pre><pre class="idle"><span class="Storage">var</span> fileName, _fn, _i, _len;
<span class="FunctionName">_fn</span> = <span class="Storage">function</span>(<span class="FunctionArgument">fileName</span>) {
<span class="Keyword">return</span> fs.readFile(fileName, <span class="Storage">function</span>(err, contents) {
<span class="Keyword">return</span> <span class="LibraryFunction">compile</span>(fileName, contents.<span class="LibraryFunction">toString</span>());
});
};
<span class="Keyword">for</span> (i <span class="Keyword">=</span> <span class="Number">0</span>; i <span class="Keyword">&lt;=</span> <span class="Number">3</span>; i<span class="Keyword">++</span>) {
_fn(i);
<span class="Keyword">for</span> (_i <span class="Keyword">=</span> <span class="Number">0</span>, _len <span class="Keyword">=</span> list.<span class="LibraryConstant">length</span>; _i <span class="Keyword">&lt;</span> _len; _i<span class="Keyword">++</span>) {
fileName <span class="Keyword">=</span> list[_i];
_fn(fileName);
}
</pre><script>window.example13 = "funcs = []\n\nfor i in [0..3] ->\n funcs.push (number) -> number + i\n\nalert funcs[3](2)"</script><div class='minibutton load' onclick='javascript: loadConsole(example13);'>load</div><div class='minibutton ok' onclick='javascript: var funcs, i, _fn;
funcs = [];
_fn = function(i) {
funcs.push(function(number) {
return number + i;
});
};
for (i = 0; i <= 3; i++) {
_fn(i);
};alert(funcs[3](2));'>run: funcs[3](2)</div><br class='clear' /></div>
</pre><script>window.example13 = "for fileName in list\n do (fileName) ->\n fs.readFile fileName, (err, contents) ->\n compile fileName, contents.toString()"</script><div class='minibutton load' onclick='javascript: loadConsole(example13);'>load</div><br class='clear' /></div>
<p>
<span id="slices" class="bookmark"></span>
@@ -970,12 +960,12 @@ middle = copy.slice(3, 7);;alert(middle);'>run: middle</div><br class='clear' />
numbers[<span class="Number">3</span>..<span class="Number">6</span>] <span class="Keyword">=</span> [<span class="Keyword">-</span><span class="Number">3</span>, <span class="Keyword">-</span><span class="Number">4</span>, <span class="Keyword">-</span><span class="Number">5</span>, <span class="Keyword">-</span><span class="Number">6</span>]
</pre><pre class="idle"><span class="Storage">var</span> numbers;
</pre><pre class="idle"><span class="Storage">var</span> numbers, _ref;
numbers <span class="Keyword">=</span> [<span class="Number">0</span>, <span class="Number">1</span>, <span class="Number">2</span>, <span class="Number">3</span>, <span class="Number">4</span>, <span class="Number">5</span>, <span class="Number">6</span>, <span class="Number">7</span>, <span class="Number">8</span>, <span class="Number">9</span>];
[].splice.<span class="LibraryFunction">apply</span>(numbers, [<span class="Number">3</span>, <span class="Number">4</span>].<span class="LibraryFunction">concat</span>([<span class="Keyword">-</span><span class="Number">3</span>, <span class="Keyword">-</span><span class="Number">4</span>, <span class="Keyword">-</span><span class="Number">5</span>, <span class="Keyword">-</span><span class="Number">6</span>]));
</pre><script>window.example15 = "numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]\n\nnumbers[3..6] = [-3, -4, -5, -6]\n\nalert numbers"</script><div class='minibutton load' onclick='javascript: loadConsole(example15);'>load</div><div class='minibutton ok' onclick='javascript: var numbers;
[].splice.<span class="LibraryFunction">apply</span>(numbers, [<span class="Number">3</span>, <span class="Number">4</span>].<span class="LibraryFunction">concat</span>(_ref <span class="Keyword">=</span> [<span class="Keyword">-</span><span class="Number">3</span>, <span class="Keyword">-</span><span class="Number">4</span>, <span class="Keyword">-</span><span class="Number">5</span>, <span class="Keyword">-</span><span class="Number">6</span>])), _ref;
</pre><script>window.example15 = "numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]\n\nnumbers[3..6] = [-3, -4, -5, -6]\n\nalert numbers"</script><div class='minibutton load' onclick='javascript: loadConsole(example15);'>load</div><div class='minibutton ok' onclick='javascript: var numbers, _ref;
numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
[].splice.apply(numbers, [3, 4].concat([-3, -4, -5, -6]));;alert(numbers);'>run: numbers</div><br class='clear' /></div>
[].splice.apply(numbers, [3, 4].concat(_ref = [-3, -4, -5, -6])), _ref;;alert(numbers);'>run: numbers</div><br class='clear' /></div>
<p>
Note that JavaScript strings are immutable, and can't be spliced.
</p>

8
test/test_functions.coffee
View File

@@ -22,18 +22,18 @@ obj = {
name: 'Fred'
bound: ->
(=> eq this, obj)()
do (=> eq this, obj)
unbound: ->
(-> ok this isnt obj)()
do (-> ok this isnt obj)
nested: ->
(=>
(=>
do (=>
(=>
eq this, obj
)()
)()
)
)()
}