This is more or less a readability, maintainability and/or best practice type question.
I wanted to get the SO opinion on something. Is it bad practice to return from multiple points in a function? For example.
<?php
// $a is some object
$somereturnvariable = somefunction($a);
if ($somereturnvariable !== FALSE) {
// do something here like write to a file or something
}
function somefunction($a) {
if (isset($a->value)) {
if ($a->value > 2) {
return $a->value;
} else {
return FALSE;
} else {
// returning false because $a->value isn't set
return FALSE;
}
}
?>
or should it be something like:
<?php
// $a is some object
$somereturnvariable = somefunction($a);
if ($somereturnvariable !== false) {
// do something here like write to a file or something
}
function somefunction($a) {
if (isset($a->value)) {
if ($a->value > 2) {
return $a->value;
}
}
return FALSE
}
?>
As a matter of practice, I always try to return from ONE point in any function, which is usually the final point. I store it in a variable say $retVal and return it in the end of the function.It makes the code look more sane to me.
Having said that, there are circumstances where say, in your function as the first line you check if a var is null and if yes you are returning. In this case, there is no point in holdin on to that variable, then adding additional checks to skip all the function code to return that in the end.
So...in conclusion, both ways works. It always depends on what the situation is and what you are more comfortable with.
Related
im just learning php
Im trying to add a log with comments to my functions output.
Right now it looks like this:
//the function
function add1($x){
if($GLOBALS['logging'] === 'on'){ $log[] = 'Adding 1 to '.$x;};
$a = $x + 1;
if($GLOBALS['logging'] === 'on'){
$return[] = $a;
$return[] = $log;
return $return;
}else{ return $a; };
};
//calling the function
if($GLOBALS['logging'] === 'on'){
$return = add1($x);
$number = $return[0];
$log = $return[1];
}else{ $number = add1($x); };
Im kinda annoyed by the fact i need to retype this if statement.
So i made a seperate function for returning the function
which looks like this:
//function
function log_return($data = 'x', $log = 'x'){
if($GLOBALS['logging'] === 'on'){
if($data !== 'x') $return[] = $data;
if($log !== 'x') $return[] = $log;
return $return;
} return $data;
};//function end
And returning it with:
return $return = isset($log) ? log_return($data, $log) : log_return($data);
Now my quastion is: Is there a way to call a function with function..
like:
call_function(add1($x));
so i can return it either with log or without..
Given the answer https://stackoverflow.com/a/2700760/5387193 - this should work:
function add1($a)
{
// add1 code goes here
}
function call_function($name, $param)
{
$name($param);
}
call_function('add1', $x);
On a side note, your variable and function names aren't very intuitive. Perhaps you should study how to write good quality readable code. I recommend reading chapter 9 of Refactoring by Martin Fowler, it's quite good. You can find a PDF version on the web.
Another note, your return statement return $return = isset($log) ? log_return($data, $log) : log_return($data); has a unnecessary assignment to $return. The code should simply read
return isset($log) ? log_return($data, $log) : log_return($data);
Yes, it is possible. To simplify:
function first($x) {
return $x+1;
}
function second($y) {
return $y+1;
}
echo second(first(1)); // Returns 3, ie. 1+1+1
As gview said in his comment, don't use global variables. Argument lists exist for several reasons, included but not limited to making code easier to read, edit, and debug. The same goes for function and variable names.
Moreover, your code is very messy. It can be consolidated:
function addTo($currentValue, $valueToAdd, $logging = 0)
{
if ($logging) {
logWrite('addTo', "Adding $valueToAdd to $currentValue");
return $currentValue + $valueToAdd;
} else {
return $currentValue;
}
}
function logWrite($operation, $message)
{
$log = getLog(); // maybe it's a file, or DB record or something
// perform the write, depending on your implementation
}
$number = addTo($someStaringValue, $someOtherValue, 1);
All of this said, logging should not control program flow. In other words, whether something is logged by the system or not should have no bearing on what your code is trying to do. I really think you need to take a broader view of what you're trying to do and break it up into components.
At best, your code should tell a logger to log info, and the logger itself should determine if logging is actually turned on. If it is, the info is logged. If not, then the code that calls on the logger still works and goes about its business.
What should one use?
This, without else:
function($condition) {
if($condition) {
return true;
}
return false;
}
Or this, with an else:
function($condition) {
if($condition) {
return true;
} else {
return false;
}
}
What are potential drawbacks?
Note: I understand that right solution for this very example would be
function($condition) {
return (boolean)$condition;
}
I like this approach:
function($condition) {
$retValue = false;
if($condition) {
$retValue = true;
}
return $retValue;
}
This way you know where this function will return, (always at the end) which is good for later analyzing. You set a default value and only change it if the condition is right.
With else there is a better readability. However, both the functions are doing the same as the function is terminated by the return function. I find it also safer to use the else if in some cases you can forget using the return function which then go further to return the false.
I would use the else too, for these reasons:
Your code is better readable
In complex code, like when you use if/else within other if/else's, debugging will be much easier.
In some cases it is possible to increase readability by setting "else" aside. Two examples below are eqiuvalent. Second produces less code, though it will suit only when we return values without complex calculations in that block, but again, we can utilize functions to make it usable.
function($a, $b) {
if($a) {
if($a > $b) {
return true;
} else {
return false;
}
} else {
return false;
}
}
function($a, $b) {
if($a) {
if($a > $b) {
return true;
}
}
return false;
}
Note: if not speaking about general cases with more complex conditions assumption, this should fold to:
function($a, $b) {
return ($a and $a > $b);
}
In the first one both true and false will be returned, as when the if statement finishes, it will go and do the very next thing, return false. In the second one, one true OR false will be returned, depending on the condition. Draw backs for the first one would be that you get both true and false returned, which could confuse a function that's only asking for one parameter, and receiving two instead. This is assuming that you include this inside a larger function. I'm not sure why you would want to use the first one though. Hopefully this helps!
What are the best usages of functions that end with "return;" and what are the advantages of writing a function that ends this way?
Example:
function MyFunction() {
// (do something)
return;
}
Thank you
You shouldn't, I would always use return null; so that it is an explicit declaration of what is returned (even if it is null). I'm sure this is also in one of the PSR specs as well, but I don't know them well. To confirm that return; === return null;:
function test() {
return;
}
var_dump(test());
// NULL
As to when you would want to return null;..any function that returns something, should always return something. So maybe if you have a function that gathers and returns a value from a DB, and an error occurs:
public function retrieveData()
{
$data = DB::retrieve();
if(!$data) {
return null;
}
return $data;
}
However, a lot of functions that may have errors just return true/false on success or failure so you won't necessarily use this often.
My main point to drive home: if you don't want/need to return anything, don't return anything.
A return; says only "thats the end". Mostly useful in following examples:
function test($string) {
if(empty($string)) {
return; // If the variable is empty, then stop to work!
}
echo $string;
}
A simple example is that you can write a PHP function that spits out formatted HTML:
function printHeader($value)
{
echo "<h1>$value</h1>";
return;
}
However, since you are not returning anything, the return statement is unnecessary and can be left out.
If you are talking about a empty return;, I can think of one example, if you have code that should be executed under a condition, and more code that should be executed if that condition is not met.
function MyFunction() {
if(a < 1) {
// (do something)
return;
}
// If a >= 0 it executes the code above and the code below
// Do something else
}
I have checked a few other questions but they don't really give me the answer I expect..
My code is a like this..
private function handle()
{
if()
{
if(!condition)
{
if(!condition)
{
if(!condition)
{
if(!condition))
{
if(!condition)
{
if(!condition)
{
if(!condition)
{
if(!condition)
{
if(!condition)
{
code
}
return;
}
return;
}
return;
}
return;
}
return;
}
return;
}
return;
}
return;
}
return;
}
}
In my opinion it is readable but messy, sadly I haven't found really a way of making it look 'pretty'. Any ideas?
EDIT: Each return is different.
EDIT2: Gave an answer of my own, thanks everybody!
Conditions can be merged by a && operator..It works form left to right, which means, as soon as the any one starting from left fails, it stops evaluating the condition..
if($a) {
if($b) {
}
}
can be replaced by
if($a && $b) {
}
Use a variable check, or combine the conditions into fewer IF statements.
Variable check like so:
$execute = TRUE;
// Opposite of what you want, e.g. if you want $a only to be TRUE, do $a !== TRUE
if (condition) {
$execute = FALSE;
}
...
// If all the conditions were met, then everything is OK
if($execute === TRUE) {
// code
}else {
// return
}
Edit:
Variable check can be preferably to combining IF statements if you want more control on what returns, e.g. something specific happens if a certain condition fails, which combining conditions can not always allow for.
Like already posted use
if(condition1&&condition2){}
or if this will not work, you can also use function which stops as soon as a condition is true
function some(){
if(!conditon 1){return 0;}
if(condition 2) {return 1;}
}
this provides more power as second if works only if first doesn't satisfy.
You must choose based on your requirements. Sometimes though nested loops are unavoidable.
I thought it out and have found a nice way of doing it, basically I'll make a method for each basic condition, and I'll call them in an if statement with the bitwise AND operator (&), which don't short-circuit.
/**
* nonsql_condition - It means it doesn't check with the database
*
* sql_condition - It means it does check with the database.
*/
if(!$this->nonsql_condition() & !$this->nonsql_condition() & !$this->nonsql_condition() & !$this->nonsql_condition())
{
if(!$this->sql_condition())
{
return error;
}
if(!$this->sql_condition())
{
return error;
}
code;
}
This allows me to use fewer lines of code in my method, plus also not doing unnecessary queries to my database.
Quick question to do with php functions, it may sound silly to some of you but I dont want to get in to bad habits. Is there anything wrong with doing the following?
function do_something($val)
{
$a = 1;
if ($val==$a)
{
return true;
}
return false;
}
Instead of;
function do_something($val)
{
$a = 1;
if ($val==$a)
{
return true;
}
else
{
return false;
}
}
Sorry guys I think my example isn't great. Basically the function could insert data into a database or send an email etc. With these functions I may only need to now whether it was successful or not by returning true or false. I wanted to know whether its suitable that I can use the shorter method instead of the if-else block.
I hope that makes it clearer.
Not really. Both works the same. However, it would be much cleaner to write it like this:
function do_something($val)
{
$a = 1;
return ($val==$a) ? true : false;
}
That's totally cool, because when returning a value, the function is left and it doesn't matter what follows.
But you could shorten this with
function do_something($val)
{
$a = 1;
return $val == $a; // this condition will be evaluated to true/false
}
The shortest way to do it:
function do_something($val)
{
return ($val==1) ;
}
No, that is perfectly fine, and in fact advised in multiple cases. :)