Object Oriented CSS: Catchy Buzz-phrase or Legitim

问题:

It seems there is a new catch-phrase emerging in the web development field: object-oriented CSS.

On the face of it, this strikes me as simply being best-practice packaged up in a catchy slogan. I understand and fully respect the intentions behind the movement, but is there any more to it?

Does anyone have any further insight that sets this approach apart as something more credible or should I just take it as a reminder to make sure I inherit and cascade my classes correctly?

回答1:

I would say it's more of a catchy buzz-phrase for something already present in CSS. Of course, before we start talking about what is OO and what is not and how CSS is object-oriented, we would have to define what it actually is - which is something others have struggled with before and is subject to heated debates. But if we assume that the basic principles of OO are:

• Class
• Object
• Instance
• Method
• Message passing
• Inheritance
• Abstraction
• Encapsulation
• Polymorphism
• Decoupling

we can say, that Cascading Style Sheets are somewhat object-oriented, because they allow classes to be defined, instances/objects created (by assigning a class to an element), inheritance of classes (even multiple inheritance), abstraction (e.g. by defining styles for the plain elements) and polymorphism (by defining the same class name for different elements). Of course methods/message passing is not possible, because of the static nature of CSS.

So in general I would say its a valid approach to develop CSS in an object-oriented manner, but I would not really call it Object Oriented CSS, because at least to me, it is something deeply inherent to CSS. It would be somewhat like saying "I am doing Object Oriented Java..."

回答2:

Catchy buzz-phrase AND legitimate design approach.

Though I think some of the ideas there are a bit naive in that they tend to forget the "client changes eveything as it goes" web development paradigm.

回答3:

I think the buzzwordiness of calling it "Object-oriented CSS" is actually detracting from its usefulness and the wider adoption of the concept.

When I read up on it, I think the claim that it was OO actually slowed my understanding of what it really was.

People who know what "object-oriented" means in programming will be skeptical, because it's not really OO, is it? It's just an attempt to apply some OO principles to CSS to improve its efficiency. And on the other side, most client-side developers will not understand the concept at all if they're not programmers, and so they'll just be baffled or embarrassed.

So, great concept, needs rebranding. Maximum CSS! Power CSS! CSS Reborn! CSS Squared! CSS Prime! Something like that.

回答4:

I've been saying this for years.

CSS selectors are based on instance IDs and classes. It even supports multiple inheritance. How much more obvious could that be?

The beauty of thinking of CSS in object terms is that it becomes very straightforward to start "casting" your mark-up elements. Need that div to suddenly become INotRenderedAnymore? Just let JS extend it's class attribute to match .removed, don't mess around with style properties.

Obviously that's a fairly trite example, but the benefits should be clear - especially in the context of JS manipulation. You can decouple the JS from the actual styles it has to modify, which is both a maintenance and abstraction bonus, but also has fringe benefits like not setting very high-specificity styles directly (which CSS cannot override).

回答5:

Writing this answer all these years later for posterity. All the answers above have clearly never heard serious talk of object-oriented CSS. When the OP asked if it was a buzzword, that should have been an indication that the expression referred to a subject that merited conversation (more so than "What do we mean by object-oriented?").

Objected-Oriented CSS is a term I believe was coined by Yahoo front-end tech evangelist Nicole Sullivan, after she consulted for Facebook in refactoring their presentational front-end code into something slimmer and more manageable that could yet be extended and modified easily as time went on. The term 'object-oriented' refers not to the nature of CSS itself (as such), but to an approach to writing CSS and affected markup that lends to conciseness and extensibility.

Some example principles of OO CSS include:

• Avoid using IDs as selectors: the fact that an object is unique does not necessarily mean that its key properties should be defined in such a way that they override all others.
• Avoid long selectors based on nested markup: defining an element's appearance based on its incidental location in document structure is often a logical fallacy, and moving it to a new location will force you to re-write the selector. As with the aforementioned, this bad practice also gives cause for conditional overrides or extensions to need extra strength and specificity in their selectors, which is rarely helpful.
• Use non-semantic markup to create elements with distinct presentational purposes, rather than trying to overload all the specifics of an individual element's appearance into one rule. This leads to less verbose CSS.

Ultimately the goal of OOCSS is DRY. You shouldn't be writing thousands of lines of CSS when you're essentially creating variations of similar things.

Nicole has given some good talks on the subject – she's also written a few articles expanding on some useful techniques to employ and bad practices to avoid.

'OOCSS' is also the name of the framework she's written that gives some boilerplate code for extensible CSS layouts. How and why this framework is so good (the grids module is something I use virtually everywhere) isn't completely self-evident from the code itself, and reading up on her blog posts on the ideas behind will definitely help make better use of it and CSS in general.

回答6:

I have been embarrassing both OOCSS and the B.E.M. naming conventions for quite some time and will NEVER look back. For those who are claiming that it's just a "catchy buzz-word" or "CSS already does this stuff", do not understand the potential of writing css using both of these methodologies.

Let's look at the simplest of objects, a list with links. It comes in many different flavors:

1. Menus

2. Toolbars

3. Tabs

4. Panels (Bootstrap)

In OOCSS, we find the common properties of each of these and create a base object. I usually call it nav.

/*  Nav
    =================================================*/

    /*  B
        ---------------------------------------------*/

        .nav
        {
            margin-left:            0;

            padding-left:           0;

            list-style:             none;
        }

    /*  E
        ---------------------------------------------*/

        .nav__item
        {
            float:                  left;
        }

        .nav__link
        {
            display:                block;

            color:                  inherit;

            text-decoration:        none;
        }

    /*  M
        ---------------------------------------------*/

        .nav--right
        {
            float:                  right;
        }

        .nav--stack .nav__item
        {
            float:                  none;
        }

You will notice a few things:

1. Nav is the base object that gets applied to the block element

2. Child elements are prefixed with nav_

3. Modifiers are prefixed with nav--

4. A modifier is an option that changes behavior. For example --right floats nav right.

Once I have my base object witten, I create skins that will change the appearance of the object. This will turn it into toolbars, tabs, etc. Microsoft has Pivot tabs on their phones. It is an easier skin to create fpr now.

/*  Nav
    =================================================*/

    /*  E
        ---------------------------------------------*/

        .pivot .nav__item
        {
            margin-left:            24px;

            color:                  #aaa;

            font-size:          36px;
        }

        .pivot .nav__item--active, .pivot .nav__item:hover
        {
            color:                  #000;
        }

To use this object and skin, you would write

<ul class="pivot nav">

   <li class="nav__item">

        <a class="nav__link"> Item 1 </a>

    </li>

   <li class="nav__item">

        <a class="nav__link"> Item 2 </a>

    </li>

</ul>

Because of its location independence, you can also write it as

<nav class="pivot nav">

   <div class="nav__item">

        <a class="nav__link"> Item 1 </a>

    </li>

   <div class="nav__item">

        <a class="nav__link"> Item 2 </a>

    </div>

</nav>

Ultimately, you are separating the container from the skin. I would suggest start smaller with Nicole Sullivans Media Object. Take a look at Twiter Bootstrap and Inuit.css for more inspiration.

回答7:

The term "Object-oriented CSS" is a misnomer.

"Object-oriented CSS" is really just a design pattern for how to get most out of your CSS and is basicly the same approach Jonathan Snooks calls SMACSS.

Whether you call it OOCSS or SMACSS, the key to the approach is that you create generic UI elements like the nav abstraction. These UI elements can then be enhanced with more specific features by adding extra classes to the element and/or a container element. Or, as an alternative, you can add your own custom CSS rules using the element's ID or semantic classes.

Cascade Framework is a brand new CSS framework based on this approach. It gives you optimal performance, optimal flexibility and optimal modularity with just a tiny footprint.

回答8:

CSS is similar to OO languages in many ways: write

p { color: red }
p span { color: blue }

and you have essentially the inheritance. Here's more complicated example with having terrier extend dog extend animal classes:

.animal { font-weight:bold; color: blue; } 
.dog:before, .terrier:before { content: "GRRR"; }
.animal, .dog, .terrier { color: brown } 

Now you can use classes animal, dog and terrier in an OO manner.

It is important to remember that CSS very good in solving the problem it's been made for: specifying the styles for elements in a transparent way. Could it be better with more OO concepts? I'm not sure. Let's say somebody says: the CSS file would be simpler if it looked like:

@class dog @derives_from animal /* the syntax i just invented */
@class terrier @derives_from dog

.animal { font-weight:bold; color: blue; } 
.dog:before { content: "GRRR"; }
.terrier { color: brown } 

This does look simpler, but an even simpler solution is to drop @class thing while adding 'dog' to any 'terrier' and 'animal' to any 'dog' server-side (trivial replace statement) or with javascript.

The best thing about CSS is that it's simple and it falls back easily, meaning browsers don't need to interpret CSS they don't understand and things works out reasonably fine. Since you'll have to break this backward compatibility with major new CSS structures, I think this makes object-oriented CSS more of a buzz phrase.

回答9:

its really one of those debatable things like tables vs divs etc etc.

In my opinion, theres a lot of developers so entrenched in OO that they try to stick it on everything, first Javascript and now CSS. Dont get me wrong JavaScript has elements of OO as well, but i digress.

Since CSS is already a buzzword in itself (all the employers want the web 2.0 CSS approach) a lot of new developers are discovering it. This is not a bad thing, however as developers they did what they do best and tried to improve on CSS. In a developers mind (I'm a developer) organizing CSS according to the OO principles makes perfect sense - hence the new buzzword.

Ultimately what I am trying to say is that OO CSS is just an approach that certain people take, since it seems more logical. If you are writing CSS that is going to be maintained by developers then this approach will suit well. It really comes down to you how you write your CSS and your own personal style...

Personally I don't care how people write their CSS - if it falls on me to maintain it, Firebug makes the job trivial anyway.

回答10:

There's not much to it, i believe.

OOCSS Object Oriented Cascading stylesheet

It reduces the code to repeat over and over again and you can set a global css for foocontainer once and reuse everywhere and have custom style for header body and footer.

<div class="foocontainer header"> Your header </div> <!-- two classes -->
<div class="foocontainer body"> Your body </div>  <!-- two classes -->
<div class="foocontainer footer> Some footer </div> <!-- two classes -->

---

BEM Block--Element__Modifier

It keeps the code easy to read but ugly to write and you can easily identify the children with their parents.

<div class="foocontainer--header"> Your header </div> <!-- one class -->
<div class="foocontainer--body"> Your body </div> <!-- one class -->
<div class="foocontainer--footer> Some footer </div> <!-- one class -->