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PHP Basics

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Don't Repeat Yourself

3:35 with Alena Holligan

The DRY Principle is one of the tenets or key concepts of programing. DRY (D-R-Y) stands for Don't Repeat Yourself. If you see yourself repeating code in the same place, for example, writing the same string over and over again, it's a good sign you can improve your programming using DRY programming techniques.

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    Now that we know how to process a PHP file on the web, 0:00
    let's start putting PHP to good use. 0:03
    Remember, variables are a way to store data. 0:06
    One reason to store data in a variable 0:08
    is to use that data in multiple places in your code. 0:11
    This will also allow us to change the data in one place while 0:14
    affecting every line of code in which that data is used. 0:18
    This is one of the tenets, or key concepts, of programming. 0:23
    It's called the dry principle. 0:26
    Dry, D-R-Y, stands for don't repeat yourself. 0:28
    If you see yourself repeating code, for example writing the same string over and 0:33
    over again, It's a good sign that you can improve your programming 0:38
    by using DRY programming techniques. 0:41
    Let's go back to Workspaces and take a look at how to use the variables and 0:43
    the DRY programming principles in the name we've been using for our page. 0:49
    In the last video, I set up code block and echoed my name. 0:55
    Let's see how we can make this program more flexible using a variable. 0:59
    Instead of echoing out this string, let's change this to a variable display name. 1:03
    Before we can use the display name variable we have to give it a value. 1:13
    Let's set the value for display name at the top of our file so 1:17
    that we can use this anywhere. 1:20
    Before the opening HTML tags, and even before this doc type. 1:22
    let's add a new PHP block. 1:27
    Then we can set our variable display name equal to my name. 1:33
    We can add as many code blocks as we want throughout our page. 1:39
    Now we can save this file and refresh the browser. 1:43
    We see that nothing has changed but that's good it's working just as before. 1:47
    Now let me show you why variables are so useful. 1:51
    Let's use this display name variable in a few different places. 1:55
    Let's copy this whole code block. 2:00
    And up in the title, instead of saying PHP Basics at Treehouse, 2:04
    let's change this to PHP Basics by Alena Holligan. 2:08
    Using our display name. 2:12
    Let's add this in one more place, the copyright in the footer. 2:15
    Instead of saying Copyright 2016 Treehouse Island Inc, 2:19
    let's say Copyright 2016 Alena Holligan using our display name variable. 2:23
    We'll replace Treehouse Island Inc with our display name variable. 2:29
    Now let's save the file and refresh the browser. 2:34
    Now I have Alena Holligan in three places, the title, the left bar, and the footer. 2:37
    That makes this a little more useful. 2:43
    But now what happens if I want to change the way my name is displayed? 2:45
    Let's go back to work spaces and the first code block at the very top. 2:49
    Instead of saying Alena Holligan let's change this to Alena A Holligan. 2:53
    We'll save the file and refresh the browser. 2:59
    Now everywhere that uses the display name variable is updated to this new value. 3:02
    You're doing a fantastic job 3:06
    learning foundational programming concepts and building your first PHP driven page. 3:10
    By storing and retrieving information in a variable, 3:15
    we are able to quickly update our page when requirements change. 3:18
    Wouldn't it be nice to have changes update without us having to change anything? 3:23
    Okay so this isn't always possible but 3:28
    there are some things that we can set up and let PHP do all the work. 3:30

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