I am graduating this June, so before that I want to prepare myself for working in the industry :)
My Question:
For example I want to list all the songs in the table using a list box and this is how I implemented it:
playlist.php
<tr id='' >
<td width="" class=""> <font color=#00000 />Select Songs</td>
<td width="" colspan="">
<select size='25'multiple='multiple' id="select_songs" name="playlist_songs[]">
<?php
display_songs_list();
?>
</select></td>
</tr>
and I have a seperate php_functions.php file where I have implemented all the php functions
function display_songs_list(){
$query = "select * from songs order by ID asc";
$result = mysql_query($query);
if(!$result)
echo "<script language = 'javascript'>alert('$result Sorry couldn't connect to the database...');</script>";
else{
$num_rows = mysql_num_rows($result);
if($num_rows > 0){
while($row = mysql_fetch_array($result)){
$ID = $row['ID'];
$title = $row['title'];
$value = $ID.'_'.$title;
echo "<option id=\"$ID\" value=\"$value\">$ID : $title</option>";
}
}
}
}
Is this way of implementation recommended. What else I can do to increace the scalability/maintainability/re-usability. please guide me on this. Is it recommended to follow any industry coding standards, if so what you perfer. Thank you.
Inline style attributes (color=#00000) are deprecated and kill kittens. Learn about CSS.
Tables are discouraged for anything except tabular data (think spreadsheets), use CSS for layout instead.
Hardcoding whitespace with is not desirable either if it doesn't add any meaning, learn to add spacing using CSS.
echoing either HTML or Javascript from the same function is bad. The Javascript alert will cause invalid HTML syntax at the point you're calling the function.
Mixing database calls and HTML so tightly is not good. Look into MVC separation.
Outputting a random, rather meaningless Javascript alert to the user in the middle of a half finished page is bad. You should display a dedicated error page instead. See MVC, which helps you accomplish this.
Mixing single quotes and double quotes for the attributes is inconsistent and makes the code more difficult to read. Stick to one type of quotes instead.
There is no form in your markup shown to submit the selected select options
Take my advice with a grain of salt, but first, you should really separate the code that talks with the database from the code that's given the user errors, they are two separate things. So an idea of how to achieve that in php might be a function that queries the database and returns an associate array with all the results that another function then prints. Also, you should have a more general database class that all your queries go through. The reason this would be preferred is that you can easily switch databases at a later point in time with minimal changes to your code, but if in every function you call mysql_query() it could become more complicated.
Its a reasonably good approach to take for php.
I normally split up my code into an Model/View/Controller type model.
The "controller" is the program which runs when the URL hits the server. It:-
grabs and checks any get/posted variables from the screen.
kicks of any requested actions such as database updates.
kicks of some "model" functions to get the data for the next screen.
formats the next screen using a "view" function or functions.
Note the controller doesn't itself emit any html.
The "model" functions do the database access and apply "business" rules.
The "view" functions emit html tags etc.
Apart from general neatness the big advantage of this is that you processing sequences isn't tied to the order the fields appear on the screen. So it really does make the programs more maintainable.
Related
So I'm importing ExpressionEngine fields into a php array. I want to display one field, called {gearboxx_body}, unless that field has more then 300 characters, in which case I want to display a field called {article_blurb}. I'm pretty sure there isn't a way to do this just in ExpressionEngine fields and conditionals, so I tried some PHP, which I'm just starting to learn:
<?php
$info = array('{gearboxx_body}','{article_blurb}');
if(mb_strlen($info[0]) <= 300)
echo($info[0]);
}
else {
echo($info[1]);
}
?>
So that works well, but there's a problem. If the tag includes any apostrophes or quote marks, it ends the string and the page won't load. So what can I do about this? I've tried to replace the quote marks in the string, but I have to have loaded the string from the fields first, and as soon as I do that the page is already broken.
Hopefully that made sense. Any suggestions?
I would recommend you handle this in an EE plugin rather than in the template:
Faster to render (because you don't need the overhead of PHP in the templates)
More secure and reliable
Faster to develop once you get the basics of EE development down which is a useful life skill
All around best-practice
The plugin I have in mind takes three parameters:
body, blurb and character limit.
Let's say you call your plugin "Blurby". In the template you would just have this:
{exp:blurby body="{gearboxx_body}" blurb="{article_blurb}" char_limit="300"}
It variably returns either of your fields based on the logic you define in the plugin itself.
See plugin developer documentation.
Alternatively you could use the dreaded HEREDOC syntax to set variables before passing them into your array:
$body = <<<EOT
{gearboxx_body}
EOT;
$blurb = <<<EOT
{article_blurb}
EOT;
I'm rather new to programming and i know how to separate PHP from HTML, but i would like to know if there is any difference in doing
this:
<?php $rand="I love apples" ?>
<h1>This is a title</h1>
<div>
<p>This is a paragraph</p>
<?php echo"The variable contains the string $rand"; ?>
</div>
?>
compared to doing this:
<?php
echo "<h1>This is a title</h1>";
echo "<div>";
echo "<p>This is a paragraph</p>";
echo "The variable contains the string $rand";
echo "</div>";
?>
Is there any difference between in performance etc, between splitting the PHP code from the HTML code and just echoing the whole page in php?
The best practice is not to seperate PHP from HTML, the best practice is to seperate logic from markup.
Also important is coding style. Proper line indentions. Using echo "</div>"; instead of echo"</div>";, valid HTML, not putting variables into quotations:
echo "The variable contains the string $rand";
better (why? see my comment below):
echo "The variable contains the string ",
$rand,
" :-)";
Your whole project gains much quality and worthness just by improving the code, writing clean, readable, maintainable. Imagine you want to change the Text, you would have to add or change lots of echoes.
Code Style Guides > Pear,
PSR, Zend <
encourage developers to keep their code readable, valid and cross-browser compatible
The problem is not performance, it's about readability and more importantly, maintainability.
Doing all the processing in one place, and all of the output in another (i.e. Logic and Presentation), would mean you will have an easier time altering one without affecting the other too drastically.
To your specific question, the top method is preferable by far, for the reasons listed above.
Taking your question at face value, there are two reasons that come to mind immediately:
Assuming you're using a smart editor, echoing all your HTML will cause you to lose syntax highlighting for it, so you're less likely to catch errors.
Because everything is inside a PHP string, now you have to worry about escaping all your other special characters. Try spitting out some Javascript with a string in it and let us know how fun that is.
However, when most people say something like "separating PHP from HTML" they are referring to the concept of separating your logic from your views. It means don't put complex business logic, computations, and database calls inside your html pages. Keep that all in pure PHP files, and have your html files contain minimal PHP that's only used to spit out your data.
<?php $rand="I love apples" ?>
<h1>This is a title</h1>
<div>
<p>This is a paragraph</p>
<?php echo"The variable contains the string $rand"; ?>
</div>
?>
The above looks poorly separated. This is what php/html separation should look like:
<?php
$rand="I love apples";
?>
<h1>This is a title</h1>
<div>
<p>This is a paragraph</p>
<p>The variable contains the string <?=$rand ?></p>
</div>
Performance-wise, that's not an issue but it would do much favor for programmers to be able to read the code easily, hence the need for HTML/PHP separation practices. Ideally, if you're going to do just one script, keep all your PHP code at top. Also, other reason for the separation is that IDE editors can easily format HTML nicely. If there's a HTML tag inside the PHP tag that is ending with a HTML tag outside of PHP, then HTML cannot be formatted correctly. For example:
<div><p>And it offers so much <?php echo "$features</p>
<h2>Proven Ideas";?></h2>
<p>More details ahead</p>
</div>
The above will run just fine but the IDE html formatter will likely be confused with missing end tags and won't format making it more difficult for programmers to read them.
I think you example is not a good one that makes it very clear why you should separate it.
The reason why you should separate not just HTML but the presentation, rendering or UI part of your application is clean coding and separation of concerns. This will make sure your get clean, easy to read code and makes your application maintable.
Take Wordpress for example, it is an extremely fugly mix of php and HTML. They even do SQL queries in the presentation layer of the application, if you can even draw a borderline between presentation and other logic in this thing.
You'll always have to output some dynamic content in your HTML but really try to reduce it to echoing variables and having some output formatting helper objects there. All business logic should be somewhere else, just not in the "templates" or whatever else you'll call the files that contain the output.
Have a look at the MVC pattern for example, it gives you a good idea of how and why you want to separate things.
In my opinion, it depends on the level of HTML formatting that is being done versus PHP logic. Nothing more & nothing less. It’s simply easier to read pure HTML as pure HTML or PHP as straight PHP. When it is all jummbled together—the way some templating systems handle it—it becomes a logical headache to read & debug. So I err on the side of placing HTML in PHP for my own sanity’s sake.
Unclear on the performance pluses or minuses if there are any. But can assure you that in 20+ years I have never had a server slow down because of too much HTML embedded in PHP
Personally, I would format your code example like this:
<?php
echo "<h1>This is a title</h1>"
. "<div>"
. "<p>This is a paragraph</p>"
. "The variable contains the string $rand"
. "</div>"
;
?>
I like this method since there is one echo—which makes it clear what is happening—and the rest of the HTML is just concatenated via . characters.
Also, remember all formatting in programming benefits HUMANS more than anything. A computer only needs to see the commands, so if you want to be pitch perfect for a machine, just code without any spaces or formatting. Heck, stop using full words & just use 1 letter variables! Oh wait, that is how it was done in ye olden days.
Nowadays compilers & caching systems are designed to take human readable code & make it machine optimized.
Which is all to say: You should code towards readability & logic on your part. Nothing more & nothing less.
This question is about optimizing a part of a program that I use to add in many projects as a common tool.
This 'templates parser' is designed to use a kind of text pattern containing html code or anything else with several specific tags, and to replace these by developer given values when rendered.
The few classes involved do a great job and work as expected, it allows when needed to isolate design elements and easily adapt / replace design blocks.
The patterns I use look like this (nothing exceptional I admit) :
<table class="{class}" id="{id}">
<block_row>
<tr>
<block_cell>
<td>{content}</td>
</block_cell>
</tr>
</block_row>
</table>
(Example code below are adapted extracts)
The parsing does things like that :
// Variables are sorted by position in pattern string
// Position is read once and stored in cache to avoid
// multiple calls to str_pos or str_replace
foreach ($this->aVars as $oVar) {
$sString = substr($sString, 0, $oVar->start) .
$oVar->value .
substr($sString, $oVar->end);
}
// Once pattern loaded, blocks look like --¤(<block_name>)¤--
foreach ($this->aBlocks as $sName=>$oBlock) {
$sBlockData = $oBlock->parse();
$sString = str_replace('--¤(' . $sName . ')¤--', $sBlockData, $sString);
}
By using the class instance I use methods like 'addBlock' or 'setVar' to fill my pattern with data.
This system has several disadvantages, among them the multiple objects in memory (one for each instance of block) and the fact that there are many calls to string manipulation functions during the parsing process (preg_replace in the past, now just a bunch of substr and pals).
The program on which I'm working is making a large use of these templates and they are just about to show their limits.
My question is the following (No need for code, just ideas or a lead to follow) :
Should I consider I've abused of this and should try to manage so that I don't need to make so many calls to these templates (for instance improving cache, using only simple view scripts...)
Do you know a technical solution to feed a structure with data that would not be that mad resource consumer I wrote ? While I'm writing I'm thinking about XSLT, would it be suitable, if yes could it improve performances ?
Thanks in advance for your advices
Use the XDebug extension to profile your code and find out exactly which parts of the code are taking the most time.
Is there an standard output library that "knows" that php outputs to html?
For instance:
var_dump - this should be wrapped in <pre> or maybe in a table if the variable is an array
a version of echo that adds a "<br/>\n" in the end
Somewhere in the middle of PHPcode I want to add an H3 title:
.
?><h3><?= $title ?></h3><?
Out of php and then back in. I'd rather write:
tag_wrap($title, 'h3');
or
h3($title);
Obviously I can write a library myself, but I would prefer to use a conventional way if there is one.
Edit
3 Might not be a good example - I don't get much for using alternative syntax and I could have made it shorter.
1 and 2 are useful for debugging and quick testing.
I doubt that anyone would murder me for using some high-level html emitting functions of my own making when it saves a lot of writing.
In regards to #1, try xdebug's var_dump override, if you control your server and can install PHP extensions. The remote debugger and performance tools provided by xdebug are great additions to your arsenal. If you're looking only for pure PHP code, consider Kint or dBug to supplement var_dump.
In regards to #2 and #3, you don't need to do this. Rather, you probably shouldn't do this.
PHP makes a fine HTML templating language. Trying to create functions to emit HTML is going to lead you down a horrible road of basically implementing the DOM in a horribly awkward and backwards way. Considering how horribly awkward the DOM already is, that'll be quite an accomplishment. The future maintainers of your code are going to want to murder you for it.
There is no shame in escaping out of PHP to emit large blocks of HTML. Escaping out to emit a single tag, though, is completely silly. Don't do that, and don't create functions that do that. There are better ways.
First, don't forget that print and echo aren't functions, they're built in to the language parser. Because they're special snowflakes, they can take a list without parens. This can make some awkward HTML construction far less awkward. For example:
echo '<select name="', htmlspecialchars($select_name), '</select>';
foreach($list as $key => $value) {
echo '<option value="',
htmlspecialchars($key),
'">',
htmlspecialchars($value),
'</option>'
}
echo '</select>';
Next, PHP supports heredocs, a method of creating a double-quoted string without the double-quotes:
$snippet = <<<HERE
<h1>$heading</h1>
<p>
<span class="aside">$aside_content</span>
$actual_content
</p>
HERE;
With these two tools in your arsenal, you may find yourself breaking out of PHP far less frequently.
While there is a case for helper functions (there are only so many ways you can build a <select>, for example), you want to use these carefully and create them to reduce copy and paste, not simply to create them. The people that will be taking care of the code you're writing five years from now will appreciate you for it.
You should use a php template engine and just separate the entire presentation and logic. It make no sense for a educated programmer to try to create a library like that.
What is more efficient and/or what is better practice, to echo the HTML or have many open and close php tags?
Obviously for big areas of HTML it is sensible to open and close the php tags. What about when dealing with something like generating XML? Should you open and close the php tags with a single echo for each piece of data or use a single echo with the XML tags included in quotations?
From a maintenance perspective, one should have the HTML / XML as separate from the code as possible IMO, so that minor changes can be made easily even by a non-technical person.
The more a homogeneous block the markup is, the cleaner the work.
One way to achieve this is to prepare as much as possible in variables, and using the heredoc syntax:
// Preparation
$var1 = get_value("yxyz");
$var2 = get_url ("abc");
$var3 = ($count = 0 ? "Count is zero" : "Count is not zero");
$var4 = htmlentities(get_value("def"));
// Output
echo <<<EOT
<fieldset title="$var4">
<ul class="$var1">
<li>
$var2
</li>
</ul>
</fieldset>
EOT;
You will want to use more sensible variable names, of course.
Edit: The link pointed out by #stesch in the comments provides some good arguments towards using a serializer when producing XML, and by extension, even HTML, instead of printing it out as shown above. I don't think a serializer is necessary in every situation, especially from a maintenance standpoint where templates are so much more easy to edit, but the link is well worth a read. HOWTO Avoid Being Called a Bozo When Producing XML
Another big advantage of the separation between logic and content is that if transition to a templating engine, or the introduction of caching becomes necessary one day, it's almost painless to implement because logic and code are already separated.
PHP solves this problem by what is known as heredocs. Check it out please.
Example:
echo <<<EOD
<td class="itemname">{$k}s</td>
<td class="price">{$v}/kg</td>
EOD;
Note: The heredoc identifer (EOD in this example) must not have any spaces or indentation.
Whichever makes sense to you. The performance difference is marginal, even if a large echo is faster.
But an echo of a big string is hard to read and more <?php echo $this->that; ?> tell a story :)
echo sends its argument further down the request processing chain, and eventually this string is sent to the client through a say, network socket. Depending on how the echo works in conjunction with underlying software layers (e.g. webserver), sometimes your script may be able to execute faster than it can push data to the client. Without output buffering, that is. With output buffering, you trade memory to gain speed - you echos are faster because they accumulate in a memory buffer. But only if there is no implicit buffering going on. One'll have to inspect Apache source code to see how does it treat PHPs stdout data.
That said, anything below is true for output buffering enabled scripts only, since without it the more data you attempt to push at once the longer you have to wait (the client has to receive and acknowledge it, by ways of TCP!).
It is more efficient to send a large string at once than do N echos concatenating output. By similar logic, it is more efficient for the interpreter to enter the PHP code block (PHP processing instruction in SGML/XML markup) once than enter and exit it many times.
As for me, I assemble my markup not with echo, but using XML DOM API. This is also in accordance with the article linked above. (I reprint the link: http://hsivonen.iki.fi/producing-xml/) This also answers the question whether to use one or many PHP tags. Use one tag which is your entire script, let it assemble the resulting markup and send it to the client.
Personally I tend to prefer what looks the best as code readability is very important, particularly in a team environment. In terms of best practice I'm afraid I'm not certain however it is usually best practice to optimize last meaning that you should write it for readability first and then if you encounter speed issues do some refactoring.
Any issues you have with efficiency are likely to be elsewhere in your code unless you are doing millions of echo's.
Another thing to consider is the use of an MVC to separate your "views" from all of your business logic which is a very clean way to code. Using a template framework such as smarty can take this one step further leading to epic win.
Whatever you do, don't print XML!
See HOWTO Avoid Being Called a Bozo When Producing XML
I've made myself the same question long time ago and came up with the same answer, it's not a considerable difference. I deduct this answer with this test:
<?
header('content-type:text/plain');
for ($i=0; $i<10; $i++) {
$r = benchmark_functions(
array('output_embeed','output_single_quote','output_double_quote'),
10000);
var_dump($r);
}
function output_embeed($i) {
?>test <?php echo $i; ?> :)<?
}
function output_single_quote($i) {
echo 'test '.$i.' :)';
}
function output_double_quote($i) {
echo "test $i :)";
}
function benchmark_functions($functions, $amount=1000) {
if (!is_array($functions)||!$functions)
return(false);
$result = array();
foreach ($functions as $function)
if (!function_exists($function))
return(false);
ob_start();
foreach ($functions as $idx=>$function) {
$start = microtime(true);
for ($i=0;$i<$amount;$i++) {
$function($idx);
}
$time = microtime(true) - $start;
$result[$idx.'_'.$function] = $time;
}
ob_end_clean();
return($result);
}
?>