lect09a-includes-http-headers
multiple pages, multiple files

From PHP Visual Quickstart Guide by Larry Ullman
Based on notes by Jack Davis (jcdavis@radford.edu)

External Files
- include('file.php');
  Generates a warning (but not an error) if the include fails (e.g. the file can't be found).
- require('file.php');
  Generates a fatal error (stopping entire execution) if the include fails (e.g. the file can't be found).
- In either case, the included file should also have its own <?php tags.

PHP Templates : Use included files to generate a coherent identity across all pages of a site:

home page — lect09a-includes--ch08-full-page.php
another page — lect09a-includes--ch08-albums.php
The source code of all the included files: homepage source code

Tip: end file names with “-inc.php” if they aren't standalone html files, but just fragments of a page meant to be included by others.

Tip: Minimize unmatched tags within an included file — it makes the fragments more re-usable in more contexts. Also, editing tools, parsers, etc. will be better able to work with those files. (For example, my editor's keyword-coloring and auto-indenting gets goofed up if I'm working with a inc file which has unmatched tags.)

So rather than:

<?php require('header-inc.php'); // This file includes '<html><head>..</head><body>', with dangling '<body>') ?>

<p>
  My page-specific content.
</p>

<?php require('footer-inc.php'); // This file ends with '<body><html>') ?>

use something like:

<?php require('doctype-inc.php'); ?>
<html>
  <?php require('header-inc.php'); // This file includes <head>...</head>') ?>
  <body>
    <?php require('page-top.php'); // This file includes a banner.) ?>

    <p>
      My page-specific content.
    </p>

  <?php require('footer-inc.php'); // This file includes contact-info ?>
  <body>
<html>

This practice is arguable, though; there is a price to shattering one page into too many included files. (E.g. for a high-performance site like amazon, you might be willing to trade-off poor design for efficiency.)

Also, it's nice to have the file for each page containing nothing more than one header/closer file without presuming any sort of page structure.

Though even in this case, consider using some framework to keep your page-source well organized/separated, and then write scripts to transform this into an efficient, optimized server arrangment. For example, each page's content might be entirely standalone frame, and the build system creates end files which combines that with header/footer/navigation files appropriately.

What if you want/need to nest requires?

Constants

define('CURRENCY','euros');

print CURRENCY;
print "468 CURRENCY";   # Just a string literal — won't print the value of the constant
print '468 ' . CURRENCY; # Will print the value of CURRENCY.

Sending e-mail from a php script at RU
mail(to, subject, body); php program that can send an email
- ob_start() — starts output buffering: Rather than echo/print statements going to stdout, they are stored in a buffer. Call this method before doing a bunch of printing.
- ob_get_clean() — Returns the current output buffer (one big string), and clears it.
- A typical use:
  At the start of your php file (in an included header?), you ob_start();.
  Then at the end of your entire file (in an included footer?), you echo ob_get_clean();.
- Fortunately, output buffers nest correctly (so if you call a function that uses ob_start() a new buffer gets created, and does't interfere with any buffering already happening; when that function does an ob_get_clean(), then it the buffering is “restored” to the dynamically-surrounding function.)
HTTP Headers
- header: create the http header.
- E.g. header('Location:page.php'); creates an http header to be returned to client, which will cause the client to redirect to page.php
- Must be called before anything is written to the php output file
- Header Function Example (Note: header instructs to forward after 10s.)
  One can also use the html header to specify the cache-expiration date of a page. (Helpful when appropriate — it lets browsers use cache in response to 'back' button.)

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©2012, Ian Barland, Radford University
Last modified 2012.Oct.12 (Fri) Please mail any suggestions
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lect09a-includes-http-headers multiple pages, multiple files

lect09a-includes-http-headers
multiple pages, multiple files