{"id":1370,"date":"2018-01-19T19:22:45","date_gmt":"2018-01-19T19:22:45","guid":{"rendered":"http:\/\/goofy-trucks.flywheelsites.com\/php-and-classes\/"},"modified":"2018-01-19T19:24:44","modified_gmt":"2018-01-19T19:24:44","slug":"php-and-classes","status":"publish","type":"post","link":"https:\/\/phpbuilder.com\/php-and-classes\/","title":{"rendered":"PHP and Classes"},"content":{"rendered":"
\n
\n
By Rod Kreisler<\/div>\n
on July 30, 2000<\/div>\n<\/p><\/div>\n
\n
\nThe hardest concept I’ve tried to understand since beginning to use PHP
\nwas that of classes. I’d never used a database engine but learning to
\nuse MySQL, at least for the more basic functions, was a breeze. Having
\nnever used OOP before, classes were novel as well, but understanding the
\ntheory and why it was useful escaped me. I knew they must be powerful
\nas “everything” is programmed using OOP, but for the life of me,
\nalthough I thought I understood the mechanics, I couldn’t see the
\nusefulness. Then, just a few days ago, while trying to figure out how
\nto do something with regular functions it hit me just how doing it with
\nobjects would make my job much simpler! I’m going to try to explain
\nabout them in plain English and hopefully help others like myself.<\/div>\n
\nClasses are nothing more than a collection of variables and functions
\nacting on those variables. They provide a means of thinking about
\nthings in real world terms. In other words they describe an object. An
\nobject, or instance, of a class is an actual “living, breathing”
\nstructure of that class. Let’s say we want to describe a bicycle. A
\nproper class of a bicycle might have the variables $pedals, $chain,
\n$front wheel, $rear wheel, $brakes<\/code>, and $handle_bars<\/code>. Functions of the
\nbicycle would include Stop(), Accelerate(), Coast(), TurnLeft()<\/code> and
\nTurnRight().<\/code> You can think of your script as the entity operating that
\nbike. The function Accelerate()<\/code> could be passed an argument such as
\n$Braking_Force<\/code> and use that information along with the defined instance
\nvariables (probably $brakes<\/code> and $wheels<\/code>)
\nand output some result back to your script.<\/div>\n
\nInteresting, but couldn’t all this be accomplished using regular
\nvariables and functions? Yes it could, and if you only had one bike in
\nyour script it probably wouldn’t make much sense to define a class just
\nfor it. But what if you needed several bicycles? It could become quite
\ncomplex keeping track of all those variables and making sure you pass
\nthe correct variables to the different functions, and using objects cuts
\ndown on the number of variables you need to pass because the function
\nautomatically has available to it all the variables describing the
\nobject the function is acting upon. Also, class definitions are easily
\nincluded in different scripts and you’ll be assured that a bicycle works
\nthe same way in each script! <\/div>\n
\nLet’s create a class that I actually use on almost every page on my site
\nand you might find useful, too.<\/div>\n
\nI don’t know about you, but when I’m writing a dynamic web page I hate
\nto have to stop thinking about the logical flow to worry about properly
\nformatting my HTML. As a consequence of this, I often end up with not so
\nattractive pages because I don’t want to worry about font faces and
\nsizes, or background and text colors. The solution: using a PHP class
\nto set HTML output attributes with functions to format the text!<\/div>\n
\nI call the class “Style”.<\/b> It contains the following variables that set
\nimportant HTML attributes for formatting the output:<\/div>\n
\n<\/p>\n

<?php<\/p>\n

<\/span>class\u00a0<\/span>Style\u00a0<\/span>{<\/p>\n

\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$text<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$alink<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$vlink<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$link<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$bgcol<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$face<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$size<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$align<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0var\u00a0<\/span>$valign<\/span>;<\/p>\n

}<\/p>\n

<\/span>?>
\n
<\/span>
\n<\/span>
\n<\/code><\/font><\/div>\n

\nI’m sure you’re familiar with HTML so the variables should be self-
\nexplanatory. Next I created a function for Style called Style:<\/div>\n
\n<\/p>\n

<?php<\/p>\n

<\/span>class\u00a0<\/span>Style\u00a0<\/span>{<\/p>\n

function\u00a0<\/span>Style\u00a0<\/span>(<\/span>$text<\/span>=<\/span>\"#000000\"<\/span>,<\/span>$alink<\/span>=<\/span>\"#AA00AA\"<\/span>,
\n
<\/span>$vlink<\/span>=<\/span>\"#AA00AA\"<\/span>,<\/span>$link<\/span>=<\/span>\"#3333FF\"<\/span>,
\n
<\/span>$bgcol<\/span>=<\/span>\"#999999\"<\/span>,<\/span>$face<\/span>=<\/span>\"Book\u00a0Antiqua\"<\/span>,<\/span>$size<\/span>=<\/span>3<\/span>,<\/span>$align<\/span>=<\/span>\"CENTER\"<\/span>,<\/span>$valign<\/span>=<\/span>\"TOP\"<\/span>)\u00a0{<\/p>\n

\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>text<\/span>=<\/span>$text<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>alink<\/span>=<\/span>$alink<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>vlink<\/span>=<\/span>$vlink<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>link<\/span>=<\/span>$link<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>bgcol<\/span>=<\/span>$bgcol<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>face<\/span>=<\/span>$face<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>size<\/span>=<\/span>$size<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>align<\/span>=<\/span>$align<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$this<\/span>-><\/span>valign<\/span>=<\/span>$valign<\/span>;<\/p>\n

}<\/p>\n

}
\n
<\/span>?>
\n
<\/span>
\n<\/span>
\n<\/code><\/font><\/div>\n<\/div>\n

<\/p>\n

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Next Page \u00bb<\/a><\/div>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"

The hardest concept I’ve tried to understand since beginning to use PHP was that of classes. I’d never used a database engine but learning to use<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-1370","post","type-post","status-publish","format-standard","hentry","category-tutorials"],"_links":{"self":[{"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/posts\/1370","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/comments?post=1370"}],"version-history":[{"count":1,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/posts\/1370\/revisions"}],"predecessor-version":[{"id":3245,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/posts\/1370\/revisions\/3245"}],"wp:attachment":[{"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/media?parent=1370"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/categories?post=1370"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/tags?post=1370"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}