The OpenERP Web open-source project¶

Getting involved¶

Translations¶

Bug reporting¶

Source code repository¶

Merge proposals¶

Coding issues and coding conventions¶

Javascript coding¶

These are a number of guidelines for javascript code. More than coding conventions, these are warnings against potentially harmful or sub-par constructs.

Ideally, you should be able to configure your editor or IDE to warn you against these kinds of issues.

Use `var` for all declarations¶

In javascript (as opposed to Python), assigning to a variable which does not already exist and is not explicitly declared (via var) will implicitly create a global variable. This is bad for a number of reasons:

It leaks information outside function scopes
It keeps memory of previous run, with potentially buggy behaviors
It may conflict with other functions with the same issue
It makes code harder to statically check (via e.g. IDE inspectors)

Note

It is perfectly possible to use var in for loops:

for (var i = 0; i < some_array.length; ++i) {
    // code here
}

this is not an issue

All local and global variables should be declared via var.

Note

generally speaking, you should not need globals in OpenERP Web: you can just declare a variable local to your top-level function. This way, if your widget/addon is instantiated several times on the same page (because it’s used in embedded mode) each instance will have its own internal but global-to-its-objects data.

Do not leave trailing commas in object literals¶

While it is legal to leave trailing commas in Python dictionaries, e.g.

foo = {
    'a': 1,
    'b': 2,
}

and it’s valid in ECMAScript 5 and most browsers support it in Javascript, you should never use trailing commas in Javascript object literals:

Internet Explorer does not support trailing commas (at least until and including Internet Explorer 8), and trailing comma will cause hard-to-debug errors in it
JSON does not accept trailing comma (it is a syntax error), and using them in object literals puts you at risks of using them in literal JSON strings as well (though there are few reasons to write JSON by hand)

Never use `for … in` to iterate on arrays¶

Iterating over an object with for…in is a bit tricky already, it is far more complex than in Python (where it Just Works™) due to the interaction of various Javascript features, but to iterate on arrays it becomes downright deadly and errorneous: for…in really iterates over an object‘s properties.

With an array, this has the following consequences:

It does not necessarily iterate in numerical order, nor does it iterate in any kind of set order. The order is implementation-dependent and may vary from one run to the next depending on a number of reasons and implementation details.
If properties are added to an array, to Array.prototype or to Object.prototype (the latter two should not happen in well-behaved javascript code, but you never know...) those properties will be iterated over by for…in. While Object.hasOwnProperty will guard against iterating prototype properties, they will not guard against properties set on the array instance itself (as memoizers for instance).

Note that this includes setting negative keys on arrays.

For this reason, for…in should never be used on array objects. Instead, you should use either a normal for or (even better, unless you have profiled the code and found a hotspot) one of Underscore’s array iteration methods (_.each, _.map, _.filter, etc...).

Underscore is guaranteed to be bundled and available in OpenERP Web scopes.

Use `hasOwnProperty` when iterating on an object with `for … in`¶

for…in is Javascript’s built-in facility for iterating over and object’s properties.

It is also fairly tricky to use: it iterates over all non-builtin properties of your objects [1], which includes methods of an object’s class.

As a result, when iterating over an object with for…in the first line of the body should generally be a call to Object.hasOwnProperty. This call will check whether the property was set directly on the object or comes from the object’s class:

for(var key in ob) {
    if (!ob.hasOwnProperty(key)) {
        // comes from ob's class
        continue;
    }
    // do stuff with key
}

Since properties can be added directly to e.g. Object.prototype (even though it’s usually considered bad style), you should not assume you ever know which properties for…in is going to iterate over.

An alternative is to use Underscore’s iteration methods, which generally work over objects as well as arrays:

Instead of

for (var key in ob) {
    if (!ob.hasOwnProperty(key)) { continue; }
    var value = ob[key];
    // Do stuff with key and value
}

you could write:

_.each(ob, function (value, key) {
    // do stuff with key and value
});

and not worry about the details of the iteration: underscore should do the right thing for you on its own [2].

Writing documentation¶

The OpenERP Web project documentation uses Sphinx for the literate documentation (this document for instance), the development guides (for Python and Javascript alike) and the Python API documentation (via autodoc).

For the Javascript API, documentation should be written using the JsDoc Toolkit.

Guides and main documentation¶

The meat and most important part of all documentation. Should be written in plain English, using reStructuredText and taking advantage of Sphinx’s extensions, especially cross-references.

Python API Documentation¶

All public objects in Python code should have a docstring written in RST, using Sphinx’s Python domain [3]:

Functions and methods documentation should be in their own docstring, using Sphinx’s info fields

For parameters types, built-in and stdlib types should be using the combined syntax:
```
:param dict foo: what the purpose of foo is
```
unless a more extensive explanation needs to be given (e.g. the specification that the input should be a list of 3-tuple needs to use :type: even though all types involved are built-ins). Any other type should be specified in full using the :type: field
```
:param foo: what the purpose of foo is
:type foo: some.addon.Class
```
Mentions of other methods (including within the same class), modules or types in descriptions (of anything, including parameters) should be cross-referenced.
Classes should likewise be documented using their own docstring, and should include the documentation of their construction (__init__ and __new__), using the info fields as well.
Attributes (class and instance) should be documented in their class’s docstring via the .. attribute:: directive, following the class’s own documentation.
The relation between modules and module-level attributes is similar: modules should be documented in their own docstring, public module attributes should be documented in the module’s docstring using the .. data:: directive.

Javascript API documentation¶

Javascript API documentation uses JsDoc, a javascript documentation toolkit with a syntax similar to (and inspired by) JavaDoc’s.

Due to limitations of JsDoc, the coding patterns in OpenERP Web and the Sphinx integration, there are a few peculiarities to be aware of when writing javascript API documentation:

Namespaces and classes must be explicitly marked up even if they are not documented, or JsDoc will not understand what they are and will not generate documentation for their content.

As a result, the bare minimum for a namespace is:
```
/** @namespace */
foo.bar.baz = {};
```
while for a class it is:
```
/** @class */
foo.bar.baz.Qux = [...]
```
Because the OpenERP Web project uses John Resig’s Class implementation instead of direct prototypal inheritance [4], JsDoc fails to infer class scopes (and constructors or super classes, for that matter) and has to be told explicitly.

See Documenting a Class for the complete rundown.
Much like the JavaDoc, JsDoc does not include a full markup language. Instead, comments are simply marked up in HTML.

This has a number of inconvenients:
- Complex documentation comments become nigh-unreadable to read in text editors (as opposed to IDEs, which may handle rendering documentation comments on the fly)
- Though cross-references are supported by JsDoc (via @link and @see), they only work within the JsDoc
- More general impossibility to integrate correctly with Sphinx, and e.g. reference JavaScript objects from a tutorial, or have all the documentation live at the same place.
As a result, JsDoc comments should be marked up using RST, not HTML. They may use Sphinx’s cross-references as well.

Documenting a Class¶

The first task when documenting a class using JsDoc is to mark that class, so JsDoc knows it can be used to instantiate objects (and, more importantly as far as it’s concerned, should be documented with methods and attributes and stuff).

This is generally done through the @class tag, but this tag has a significant limitation: it “believes” the constructor and the class are one and the same [5]. This will work for constructor-less classes, but because OpenERP Web uses Resig’s class the constructor is not the class itself but its init() method.

Because this pattern is common in modern javascript code bases, JsDoc supports it: it is possible to mark an arbitrary instance method as the class specification by using the @constructs tag.

Warning

@constructs is a class specification in and of itself, it completely replaces the class documentation.

Using both a class documentation (even without @class itself) and a constructor documentation is an error in JsDoc and will result in incorrect behavior and broken documentation.

The second issue is that Resig’s class uses an object literal to specify instance methods, and because JsDoc does not know anything about Resig’s class, it does not know about the role of the object literal.

As with constructors, though, JsDoc provides a pluggable way to tell it about methods: the @lends tag. It specifies that the object literal “lends” its properties to the class being built.

@lends must be specified right before the opening brace of the object literal (between the opening paren of the #extend call and the brace), and takes the full qualified name of the class being created as a parameter, followed by the character # or by .prototype. This latter part tells JsDoc these are instance methods, not class (static) methods..

Finally, specifying a class’s superclass is done through the @extends tag, which takes a fully qualified class name as a parameter.

Here are a class without a constructor, and a class with one, so that everything is clear (these are straight from the OpenERP Web source, with the descriptions and irrelevant atttributes stripped):

/**
 * <Insert description here, not below>
 *
 * @class
 * @extends openerp.base.search.Field
 */
openerp.base.search.CharField = openerp.base.search.Field.extend(
    /** @lends openerp.base.search.CharField# */ {
        // methods here
});

openerp.base.search.Widget = openerp.base.Controller.extend(
    /** @lends openerp.base.search.Widget# */{
    /**
     * <Insert description here, not below>
     *
     * @constructs
     * @extends openerp.base.Controller
     *
     * @param view the ancestor view of this widget
     */
    init: function (view) {
        // construction of the instance
    },
    // bunch of other methods
});

OpenERP Web over time¶

Release process¶

OpenSUSE packaging: http://blog.lowkster.com/2011/04/packaging-python-packages-in-opensuse.html

Roadmap¶

Release notes¶

[1]

More precisely, it iterates over all enumerable properties. It just happens that built-in properties (such as String.indexOf or Object.toString) are set to non-enumerable.

The enumerability of a property can be checked using Object.propertyIsEnumeable.

Before ECMAScript 5, it was not possible for user-defined properties to be non-enumerable in a portable manner. ECMAScript 5 introduced Object.defineProperty which lets user code create non-enumerable properties (and more, read-only properties for instance, or implicit getters and setters). However, support for these is not fully complete at this point, and they are not being used in OpenERP Web code anyway.

[2]

While using underscore is generally the preferred method (simpler, more reliable and easier to write than a correct for…in iteration), it is also probably slower (due to the overhead of calling a bunch of functions).

As a result, if you profile some code and find out that an underscore method adds unacceptable overhead in a tight loop, you may want to replace it with a for…in (or a regular for statement for arrays).

[3]	Because Python is the default domain, the `py:` markup prefix is optional and should be left out.

[4]	Resig’s Class still uses prototypes under the hood, it doesn’t reimplement its own object system although it does add several helpers such as the `_super()` instance method.

[5]	Which is the case in normal Javascript semantics. Likewise, the `.prototype` / `#` pattern we will see later on is due to JsDoc defaulting to the only behavior it can rely on: “normal” Javascript prototype-based type creation.