I got confronted with this "problem" several times already, I fix it the same way but I feel dirty just by thinking how I solved it.
Let's say I work with Drupal 8 and that I need to modify several select form's default value, "-Any-" by "Select...".
This is how I proceed each time :
if(isset($form['field_children_charge_value'])) {
$form['field_children_charge_value']['#options']['All'] = t('Select...');
}
if(isset($form['field_evolution_target_id'])) {
$form['field_evolution_target_id']['#options']['All'] = t('Select...');
}
// And so on
I feel bad writing like this, but, for my defense, I didn't have a lot of of PHP theory while learning, I directly got the practical courses.
an elseif expression would only work once since the first condition will match the pre requisite, and it won't bother checking if some other condition would work too.
I also got the problem once with javascript, and I did the same thing.
So, is there a better syntax, and if yes, what is it?
Been years since I coded in php, but this seems like a general "issue".
You can save all the fields in an array, and then use a for-each loop to execute the operation on each of them:
$fields = ["field1", "field2", "..."];
foreach($fields as $field) {
if(isset($form[$field])) {
$form[$field]['#options']['All'] = t('Select...');
}
}
Related
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Why should a function have only one exit-point?
As a CS student I have had it beaten into my head that there should only be one exit point in a function, at the end.
eg. This:
function foo()
{
//do stuff here
if($bar)
{
$out = FALSE;
}
else
{
$out = TRUE;
}
return $out;
}
Not:
function foo()
{
//do stuff here
if($bar)
{
return FALSE;
}
return TRUE;
}
However I have seen this second type of exiting used quite often in other peoples code in php, and even in core code for some frameworks (like Kohana which I have been using lately).
Is this method of exiting a function considered okay in php standards?
Edit: I can see why I have been told not to do it as it can be easier to track some problems in a function with one exit point, other times I can see why it should be allowed as other problems are better solved or tracked in functions with multiple exit points.
Edit 2: Added "do stuff here" comments to the code example to make people happy
I've always used the latter route, since you would have to declare $out and have one more variable in existence. But in retrospect, it's just a boolean -- it's not doing any harm. The first route could look cleaner, depending on the context of your code.
It all comes down to consistency. As long as you have a system, determining when it is time to use route 1 or route 2, you're doing great.
It's six of one, or half a dozen of another - happiness lies in consistency.
I've seen (good) code return values both ways. If you're using a framework/codebase that consistently uses one way, I would follow that. Otherwise, use what you're comfortable using. :D
2 short questions based on trying to make my code more efficient (I think my ultimate quest is to make my entire (fairly complex) website based on some sort of MVC framework, but not being a professional programmer, I think that's going to be a long and steep learning curve..)
In this code, is there a way to merge the if statement and for loop, to avoid the nesting:
if($fileatt['name']!=null)
{
$attachedFiles = "You uploaded the following file(s)\n";
for($i=0;$i<count($docNames);$i++)
{
$attachedFiles = $attachedFiles. " - " . $docNames[$i] . "\n";
}
}
At the moment, I do the fairly standard thing of splitting my $_POST array from a form submission, 'clean' the contents and store the elements in individual variables:
$name = cleanInput($_POST['name']);
$phone = cleanInput($_POST['phone']);
$message = cleanInput($_POST['message']);
...
(where cleanInput() contains striptags() and mysql_real_escape_string())
I had thought that keeping all the information in an array might my code more efficient, but is there a way to apply a function to all (or selected) elements of an array? For example, in R, this is what the apply() function does.
Alternatively, given that all my variables have the same name as in the $_POST array, is there a way to generate all the variables dynamically in a foreach loop? (I know the standard answer when people ask if they can dynamically generate variables is to use a hashmap or similar, but I was interested to see if there's a technique I've missed)
You can use extract and combine it with array_map
extract(array_map('cleanInput', $_POST), EXTR_SKIP);
echo $name; // outputs name
Be warned that $_POST could be anything and user can then submit anything to your server and it becomes a variable in your code, thus if you have things like
if(empty($varName)) { } // assumes $varName is empty initially
Could easily bypassed by user submitting $_POST['varName'] = 1
To avoid mishaps like this, you can have a whitelist of array and filter out only those you need:
$whitelist = array('name', 'phone', 'message');
$fields = array();
foreach($_POST as $k => $v) {
if(in_array($k, $whitelist)) $fields[$k] = $v;
}
extract(array_map('cleanInput', $fields));
1) To the first question, how to merge the if and the for loop:
Why would you want to merge this, it will only make the code more difficult to read. If your code requires an if and afterwards a for loop, then show this fact, there is nothing bad with that. If you want to make the code more readable, then you can write a function, with a fitting name, e.g. listAttachedFiles().
2) To the question about cleaning the user input:
There is a difference between input validation and escaping. It's a good thing to validate the input, e.g. if you expect a number, then only accept numbers as input. But escaping should not be done until you know the target system. So leave the input as it is and before writing to the db use the mysql_real_escape_string() function, before writing to an HTML page use the function htmlspecialchars().
Combining escape functions before needed, can lead to invalid data. It can become impossible to give it out correctly, on a certain target system.
Personally I think that the performance cost of using an "If" statement is worth the benefit of having easily readable code. Also you have to be sure that you actually use fewer cycles by combining, if there is such a way.
I'm not sure I follow your second question, but have you looked at extract() and array_walk() yet?
Point 1 is premature optimization. And you want get any better performance / readability by doing so. (similar for using arrays for everything).
Point 2 - AaaarrgghhH! You should only change the representation of data at the point where it leaves PHP, using a method approporiate to the destination - not where it arrives in PHP.
To make your for loop more efficient don't use Count() within the condition of your loops.
It's the first thing they teach in school. As the For loops are reevaluating the conditions at each iterations.
$nbOfDocs = count($docNames); //will be much faster
for($i=0;$i<$nbOfDocs;$i++)
{
$attachedFiles = $attachedFiles. " - " . $docNames[$i] . "\n";
}
Solution?
Apparently there isn't a faster way, I'm okay with that.
I am just learning php and I am trying to figure out some good tips and tricks so I don't get into a bad habit and waste time.
I am passing in values into a php script. I am using $_GET so the URL looks like this:
/poll_results.php?Sports=tennis&cat=Sports&question=Pick+your+favorite+sports
Now I know how to accept those values and place them into variables like so:
$sports = $_GET['Sports'];
$cat = $_GET['cat'];
$question = $_GET['question'];
Super simple yet if I am passing 5 - 6 things it can get bothersome and I don't like typing things out for every single variable, that's the only reason. I know there is a better way of doing this. I have tried list($var, $var, $var) = $_GET but that doesn't work with an associative array just indexed ones (i think).
I also tried variable variables like so:
foreach($_GET as $value) {
$$values = $value;
echo $$values;
}
But that gave me a Notice: Undefined variable: values in poll_results.php on line 14. Line 14 is the $$values = $value. I don't know if that's a big deal or not... but I'm not turning off error reporting as I am still in the process of building the script. It does do what I want it to do though...
Any answers will be copied and pasted into my question so the next person knows :D
Thanks guys!
Your second bit of code is wrong. It ought to be like
foreach ($_GET as $key => $value) {
$$key = $value;
}
if i understand your intent. However, you're basically reinventing register_globals, which....eh. That'll get ya hacked.
If you have certain variables you want to get, you could do like
foreach (array('Sports', 'cat', 'question') as $key)
{
$$key = $_GET[$key];
}
which is less likely to overwrite some important variable (whether by accident or because someone was messing around with URLs).
Use parse_url() to extract the query string from a URL you've got in a string, then parse_str() to extract the individual arguments of the query string.
If you want to pollute your script with the contents of the superglobals, then you can use extract(). however, be aware that this is basically replicating the hideous monstrosity known as "register_globals", and opens all kinds of security vulnerabilities.
For instant, what if one of the original query arguments was _GET=haha. You've now trashed the $_GET superglobal by overwriting it via extract().
I am just learning php and I am trying to figure out some good tips and tricks so I don't get into a bad habit and waste time.
If I am passing 5 - 6 things it can get bothersome and I don't like typing things out for every single variable, that's the only reason.
What you are trying to do will, unless curbed, become a bad habit and even before then is a waste of time.
Type out the variables: your digits like exercise and your brain can take it easy when it doesn't have to figure out which variables are available (or not, or maybe; which would be the case when you use variable variables).
You can use
foreach($_GET as $key => $value)
To preserve the key and value associativity.
Variable variables (the $$value) are a bad idea. With your loop above say you had a variable named $password that is already defined from some other source. Now I can send $_GET['password'] and overwrite your variable! All sorts of nastiness can result from this. It's the same reason why PHP abandoned register_globals which essentially does the same thing.
My advice: use $_POST when possible. It keeps your URLs much cleaner for one thing. Secondly there's no real reason to assign the array to variables anyway, just use them where you need them in the program.
One good reason for this, especially in a large program, is that you'll instantly know where they came from, and that their data should not be trusted.
I'm creating a simple application using the Kohana PHP framework, just FYI. This is my first time with the framework.
While developing classes or functions I'm commenting my code using DocBlock. How should I comment my code while using the framework? I meant to code some parts of the code, not whole controllers.
Basically, I'm using following methods:
// Check if variable_name is greater than zero
if($this->var > 0) {
// do something
} else {
// do something
}
if( $result ) {
// display confirmation message
} else {
// display errors
}
Am I doing it right way? Is there a standard for inserting comments in the code?
I'm not using comments like "check if variable is greater than zero". I'm just wondering if is it good practice to put comments into the code.
Not related to visual style of the comments, but a comment like "Check if variable_name is greater than zero" is a bad comment in and by itself. All it does is duplicate the information on the line below. The code should contain names on variables, functions and other things that can be read to know what's going on.
Other than that, I see nothing wrong with the double-slash-comment types.
// Check if variable_name is greater than zero
Such comments are worthless. I only know little PHP, and even if I didn't knew anything about it, I could immediately tell (or at least, very confidently guess) that after looking at the line.
As a general (language-agnostic) rule of thumb, write code that is mostly self-documenting (by using descriptive names, avoiding non-obvious shortcuts, etc.) and only comment why you do something which looks wrong/strange.
Personally, I document inline sparingly (I do religiously put doc-blocks in for methods, classes and member variables though). I believe that code itself should be as self documenting as possible.
There will be times where you need to do something non-obvious or possibly even counter-intuitive. That's the time for inline comments. Try to explain not what the block of code does, but why it does it that way.
There's a great example in Phing's CodeCoverageReportTask class:
// Strange PHP5 reflection bug,
// classes without parent class or implemented interfaces
// seem to start one line off
if ($reflection->getParentClass() == NULL
&& count($reflection->getInterfaces()) == 0)
{
unset($coverageInformation[$classStartLine + 1]);
}
else
{
unset($coverageInformation[$classStartLine]);
}
And another good one just a few lines down from that:
// PHP5 reflection considers methods of a parent class to be part
// of a subclass, we don't
if ($method->getDeclaringClass()->getName() != $reflection->getName())
{
continue;
}
I completely agree that comments should never explain what the code does, only why. But, it is definitely good practice to put necessary comments into the code. When I go back and look over some of my code (PHP or other), I wish I had commented more clearly.
But, the only standard with comments is consistency! Be consistent and you don't have to worry so much about confusing comments (only about when to use them).
Some (if not most) PHP programmers use the double-slash method (//) for commenting their code. There really is no standard, and I've seen people who comment using the pound symbol (#) at the beginning of a line, and others who comment out blocks with /* and */.
Comments are liars!
The problem with comments is that you have to update them as you update your code. If you don't, you end up with code looking like this:
// sum $a and $b
$x = $a * $a - $b;
So the best way to document your code is to make it really clear! I would write your code like this:
if ( isPositive(3) ) {
doA();
} else {
doB();
}
if( $result ) {
displayConfirmationMsg();
} else {
displayErrors();
}
This code doesn't need comments at all, because it's very simple to understand it!
Well, anyway, when I do have to write comments (almost never), I go with the // notation, but I think it doesn't really matter.
By the way, check out this awesome video of Uncle Bob.
I feel dirty every time I "break" out of a for-each construct (PHP/Javascript)
So something like this:
// Javascript example
for (object in objectList)
{
if (object.test == true)
{
//do some process on object
break;
}
}
For large objectLists I would go through the hassle building a more elegant solution. But for small lists there is no noticeable performance issue and hence "why not?" It's quick and more importantly easy to understand and follow.
But it just "feels wrong". Kind of like a goto statement.
How do you handle this kind of situation?
I use a break. It's a perfectly cromulent solution.
It's quick and more importantly easy to understand and follow.
Don't feel bad about break. Goto is frowned upon because it's quick and more importantly not easy to understand and follow.
See, the break doesn't bug me at all. Programming is built on goto, and for-break - like all control structures - is merely a special-purpose form of goto meant to improve the readability of your code. Don't ever feel bad about writing readable code!
Now, I do feel dirty about direct comparisons to true, especially when using the type-converting equality operator... Oh yeah. What you've written - if (object.test == true) - is equivalent to writing if (object.test), but requires more thought. If you really want that comparison to only succeed if object.test is both a boolean value and true, then you'd use the strict equality operator (===)... Otherwise, skip it.
For small lists, there's no issue with doing this.
As you mention, you may want to think about a more 'elegant' solution for large lists (especially lists with unknown sizes).
Sometimes it feels wrong, but it's all right. You'll learn to love break in time.
Like you said ""why not?" It's quick and more importantly easy to understand and follow."
Why feel dirty, I see nothing wrong with this.
I think is is easier to read and hence easier to maintain.
It is meant to be like it. Break is designed to jump out of a loop. If you have found what you need in a loop why keep the loop going?
Breaks and continues are not gotos. They are there for a reason. As soon as you're done with a loop structure, get out of the loop.
Now, what I would avoid is very, very deep nesting (a.k.a. the arrowhead design anti-pattern).
if (someCondition)
{
for (thing in collection)
{
if (someOtherCondition)
{
break;
}
}
}
If you are going to do a break, then make sure that you've structure your code so that it's only ever one level deep. Use function calls to keep the iteration as shallow as possible.
if (someCondition)
{
loopThroughCollection(collection);
}
function loopThroughCollection(collection)
{
for (thing in collection)
{
if (someOtherCondition)
{
doSomethingToObject(thing);
break;
}
}
}
function doSomethingToObject(thing)
{
// etc.
}
I really don't see anythign wrong with breaking out of a for loop. Unless you have some sort of hash table, dictionary where you have some sort of key to obtain a value there really is no other way.
I'd use a break statement.
In general there is nothing wrong with the break statement. However your code can become a problem if blocks like these appear in different places of your code base. In this case the break statements are code small for duplicated code.
You can easily extract the search into a reusable function:
function findFirst(objectList, test)
{
for (var key in objectList) {
var value = objectList[key];
if (test(value)) return value;
}
return null;
}
var first = findFirst(objectList, function(object) {
return object.test == true;
}
if (first) {
//do some process on object
}
If you always process the found element in some way you can simplify your code further:
function processFirstMatch(objectList, test, processor) {
var first = findFirst(objectList, test);
if (first) processor(first);
}
processFirst(
objectList,
function(object) {
return object.test == true;
},
function(object) {
//do some process on object
}
}
So you can use the power of the functional features in JavaScript to make your original code much more expressive. As a side effect this will push the break statement out of your regular code base into a helper function.
Perhaps I'm misunderstanding your use-case, but why break at all? I'm assuming you're expecting the test to be true for at most one element in the list?
If there's no performance issue and you want to clean up the code you could always skip the test and the break.
for (object in objectList)
{
//do some process on object
}
That way if you do need to do the process on more than one element your code won't break (pun intended).
Use a
Object object;
int index = 0;
do
{
object = objectList[index];
index++;
}
while (object.test == false)
if breaking from a for loop makes you feel uneasy.
My preference is to simply use a break. It's quick and typically doesn't complicate things.
If you use a for, while, or do while loop, you can use a variable to determine whether or not to continue:
for ($i = 0, $c = true; ($i < 10) && $c; $i++) {
// do stuff
if ($condition) {
$c= false;
}
}
The only way to break from a foreach loop is to break or return.