Re: [PHP] Multiple return statements in a function.
Hi,
> your function could be condensed to this:
>
> function check($a)
> {
> return is_array($a) ? true : false;
> }
Or even better, this:
function check($a)
{
return is_array($a);
}
Not that I'd imagine it makes a great deal of difference.
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Re: [PHP] Multiple return statements in a function.
At 10:25 AM -0400 4/23/09, Robert Cummings wrote: On Thu, 2009-04-23 at 10:14 -0400, tedd wrote: > However, I am saying (after years of reading other people's code) it is generally much easier to read code that follows "Structured Programming" than it is to read code that doesn't. Actually I use an early return as much as possible also. If there are 5 conditions which disqualify the rest of the function from running then they'll all be listed one after the other at the top of the function. This way it's very easy to see exactly what doesn't qualify for evaluation. Additionally, it saves on the need for that many levels of indentation or making an overly complex conditional. I find it much more intuitive than mentally tracking several levels of indentation and scrolling to the bottom of the function. Cheers, Rob. Rob: Again, I'm not arguing the point -- we actually agree. I have functions where I do that as well. My only criteria is how easy my functions are to read and understand. If by placing function entry-criteria at the beginning of the function and then returning nulls (or whatever) makes it easier for someone to review your code and understand what it does, then by all means do it. But I am sure that both of you have reviewed functions that have multiple returns spread throughout where you thought "What the hell is this? Just what is this function returning?" That is what I am addressing. The OP asked which was the better practice and I replied that it is USUALLY good practice to have only one return and have it at the end of your function -- I stand by that. Cheers, tedd -- --- http://sperling.com http://ancientstones.com http://earthstones.com -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Multiple return statements in a function.
On Thu, Apr 23, 2009 at 10:14:28AM -0400, tedd wrote: > At 2:19 PM +0100 4/23/09, Tony Marston wrote: >> There is no such "rule", it is a matter of personal preference. As a >> previous poster has already said, if you want to leave a function early >> and >> ignore all subsequent processing it is easier to understand if you return >> immediately rather than have a mechanism to jump over the remaining code >> to >> a single return point. In the good old days we used to use the GOTO in >> COBOL >> to jump to the exit point, but then people found a way to abuse GOTO in >> very >> imaginatve ways. >> >>> The "benefit" is easier to read code. >> >> I think that an immediate return is easier to read, but what do I know - >> I've only been programming for 30 years. >> >> -- >> Tony Marston > > Tony: > > Don't get your panties in a knot. :-) I think in Tony's case, it would "knickers in a twist". ;-} Paul -- Paul M. Foster -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Multiple return statements in a function.
On Thu, 2009-04-23 at 10:14 -0400, tedd wrote: > At 2:19 PM +0100 4/23/09, Tony Marston wrote: > >"tedd" wrote in message > > > It's called "Structured programming" -- one way in and one way out of a > >> function. > >> > >> There are, of course, exceptions where it might help others reviewing your > >> code to see what's going on, such as returning a null value if the > >> argument(s) provided are not suitable. But normally the rule is, do not > >> provide an exit from a function in more than one place. > > > >There is no such "rule", it is a matter of personal preference. As a > >previous poster has already said, if you want to leave a function early and > >ignore all subsequent processing it is easier to understand if you return > >immediately rather than have a mechanism to jump over the remaining code to > >a single return point. In the good old days we used to use the GOTO in COBOL > >to jump to the exit point, but then people found a way to abuse GOTO in very > >imaginatve ways. > > > >> The "benefit" is easier to read code. > > > >I think that an immediate return is easier to read, but what do I know - > >I've only been programming for 30 years. > > > >-- > >Tony Marston > > Tony: > > Don't get your panties in a knot. :-) > > I have 44 years of programming under my belt, so what? However, I > wish I could remember everything I learned during that time. > > But what I do remember is there's a school of thought called > "Structured Programming" that has a doctrine in which every function > should have only one entry and exit point. > > Now maybe you want to argue with that concept, that's fine -- but the > point remains this is a "rule" under "Structured Programming". That's > history. > > Now, I usually follow that rule for I have learned from experience > that in most cases, it is easier to read what is going on in a > function if you only have one exit. > > As I said in my post, there are of course exceptions. There are times > that requiring a function to have a single exit point will > unnecessarily create code that's hard to read -- so doing it > differently is something to consider in those cases. If you want to > have an immediate exit point in your functions and that makes your > code more readable, then that's fine and I'm not arguing that point. > > However, I am saying (after years of reading other people's code) it > is generally much easier to read code that follows "Structured > Programming" than it is to read code that doesn't. Actually I use an early return as much as possible also. If there are 5 conditions which disqualify the rest of the function from running then they'll all be listed one after the other at the top of the function. This way it's very easy to see exactly what doesn't qualify for evaluation. Additionally, it saves on the need for that many levels of indentation or making an overly complex conditional. I find it much more intuitive than mentally tracking several levels of indentation and scrolling to the bottom of the function. Cheers, Rob. -- http://www.interjinn.com Application and Templating Framework for PHP -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Multiple return statements in a function.
At 2:19 PM +0100 4/23/09, Tony Marston wrote: "tedd" wrote in message > It's called "Structured programming" -- one way in and one way out of a function. There are, of course, exceptions where it might help others reviewing your code to see what's going on, such as returning a null value if the argument(s) provided are not suitable. But normally the rule is, do not provide an exit from a function in more than one place. There is no such "rule", it is a matter of personal preference. As a previous poster has already said, if you want to leave a function early and ignore all subsequent processing it is easier to understand if you return immediately rather than have a mechanism to jump over the remaining code to a single return point. In the good old days we used to use the GOTO in COBOL to jump to the exit point, but then people found a way to abuse GOTO in very imaginatve ways. The "benefit" is easier to read code. I think that an immediate return is easier to read, but what do I know - I've only been programming for 30 years. -- Tony Marston Tony: Don't get your panties in a knot. :-) I have 44 years of programming under my belt, so what? However, I wish I could remember everything I learned during that time. But what I do remember is there's a school of thought called "Structured Programming" that has a doctrine in which every function should have only one entry and exit point. Now maybe you want to argue with that concept, that's fine -- but the point remains this is a "rule" under "Structured Programming". That's history. Now, I usually follow that rule for I have learned from experience that in most cases, it is easier to read what is going on in a function if you only have one exit. As I said in my post, there are of course exceptions. There are times that requiring a function to have a single exit point will unnecessarily create code that's hard to read -- so doing it differently is something to consider in those cases. If you want to have an immediate exit point in your functions and that makes your code more readable, then that's fine and I'm not arguing that point. However, I am saying (after years of reading other people's code) it is generally much easier to read code that follows "Structured Programming" than it is to read code that doesn't. Cheers, tedd -- --- http://sperling.com http://ancientstones.com http://earthstones.com -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Multiple return statements in a function.
Richard Heyes wrote:
> Hi,
>
>> while(true){
>
> Yikes.
>
> Personally, I'd put the return value wherever it will make the code
> easier to read. If you're checking what has been passed as arguments,
> and one of them is wrong, I think there's little point in continuing,
> so an immediate return is the order of the day.
Well, I usually use that construct where I can have a number of
different error-conditions - e.g. if I have a sequence of socket
create, DNS lookup, bind, connect etc.
/Per
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Re: [PHP] Multiple return statements in a function.
2009/4/23 Tony Marston :
>
> "tedd" wrote in message
> news:p06240805c6161613a...@[192.168.1.101]...
>> At 8:12 AM -0400 4/23/09, Peter van der Does wrote:
>>>I tend to put my return value in a variable and at the end of the
>>>function I have 1 return statement.
>>>I have seen others doing returns in the middle of the function.
>>>
>>>-snip-
>>>
>>>What is your take? And is there any benefit to either method?
>>>
>>>Peter van der Does
>>
>> Peter:
>>
>> It's called "Structured programming" -- one way in and one way out of a
>> function.
>>
>> There are, of course, exceptions where it might help others reviewing your
>> code to see what's going on, such as returning a null value if the
>> argument(s) provided are not suitable. But normally the rule is, do not
>> provide an exit from a function in more than one place.
>
> There is no such "rule", it is a matter of personal preference. As a
> previous poster has already said, if you want to leave a function early and
> ignore all subsequent processing it is easier to understand if you return
> immediately rather than have a mechanism to jump over the remaining code to
> a single return point. In the good old days we used to use the GOTO in COBOL
> to jump to the exit point, but then people found a way to abuse GOTO in very
> imaginatve ways.
>
>> The "benefit" is easier to read code.
>
> I think that an immediate return is easier to read, but what do I know -
> I've only been programming for 30 years.
>
> --
> Tony Marston
> http://www.tonymarston.net
> http://www.radicore.org
>
>> Cheers,
>>
>> tedd
>>
>> --
>> ---
>> http://sperling.com http://ancientstones.com http://earthstones.com
>
>
>
> --
> PHP General Mailing List (http://www.php.net/)
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>
As someone's who been playing this game for only 29 years, I like a
single exit point.
One of the issues I found with multiple exit points is that you have
to work a little harder to guarantee a return.
I always write my code so that if the function did nothing, then null
or false are the return values ...
function foo() {
$result = False;
// ... code which may or may nor affect $result
return $result;
}
If your code is heavily nested (maybe an indicator that some
refactoring is worth undertaking) and you introduce yet more code,
keeping track of multiple exit points can be a little problematic.
I suppose if you are the only developer then create a style and stick with it.
Don't be afraid of refactoring your code if you feel that a different
style is easier to work with.
If you work in a team, then once the team has determined its style,
stick with it. Even if it hurts. The hassle you'll get when your code
doesn't "fit" is far more than the learning curve you'll go through
getting the style.
Richard.
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Re: [PHP] Multiple return statements in a function.
Hi,
> while(true){
Yikes.
Personally, I'd put the return value wherever it will make the code
easier to read. If you're checking what has been passed as arguments,
and one of them is wrong, I think there's little point in continuing,
so an immediate return is the order of the day. Though with
exceptions, this could be mitigated (IIRC). BTW there's also something
to be said for code conciseness, which I think is loosely related. Eg
your function could be condensed to this:
function check($a)
{
return is_array($a) ? true : false;
}
But then the question is nullified somewhat.
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Re: [PHP] Multiple return statements in a function.
George Larson wrote:
> That's an interesting subject that I've never considered.
>
> I usually return immediately. For me, it makes the code easier to
> read. I work with a number of other coders here and, if the result
> isn't returned then I have to keep reading through the code to make
> sure nothing else is done with it. However, when I see the 'return'
> then I know we're done there.
I tend to try to have just one return point, but I will occasionally
have more, typically when a function returns more than just true or
false.
If it's a true or false outcome, but I still have multiple failure
points, I'll sometimes use a construct like this:
rc=0;
while(true){
if ( cond1 ) { errormsg; rc=1; break; }
if ( cond2 ) { errormsg; rc=1; break; }
if ( cond3 ) { errormsg; rc=1; break; }
if ( cond4 ) { errormsg; rc=1; break; }
if ( cond5 ) { errormsg; rc=1; break; }
if ( cond6 ) { errormsg; rc=1; break; }
if ( cond7 ) { errormsg; rc=1; break; }
break;
}
return rc;
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Re: [PHP] Multiple return statements in a function.
"tedd" wrote in message news:p06240805c6161613a...@[192.168.1.101]... > At 8:12 AM -0400 4/23/09, Peter van der Does wrote: >>I tend to put my return value in a variable and at the end of the >>function I have 1 return statement. >>I have seen others doing returns in the middle of the function. >> >>-snip- >> >>What is your take? And is there any benefit to either method? >> >>Peter van der Does > > Peter: > > It's called "Structured programming" -- one way in and one way out of a > function. > > There are, of course, exceptions where it might help others reviewing your > code to see what's going on, such as returning a null value if the > argument(s) provided are not suitable. But normally the rule is, do not > provide an exit from a function in more than one place. There is no such "rule", it is a matter of personal preference. As a previous poster has already said, if you want to leave a function early and ignore all subsequent processing it is easier to understand if you return immediately rather than have a mechanism to jump over the remaining code to a single return point. In the good old days we used to use the GOTO in COBOL to jump to the exit point, but then people found a way to abuse GOTO in very imaginatve ways. > The "benefit" is easier to read code. I think that an immediate return is easier to read, but what do I know - I've only been programming for 30 years. -- Tony Marston http://www.tonymarston.net http://www.radicore.org > Cheers, > > tedd > > -- > --- > http://sperling.com http://ancientstones.com http://earthstones.com -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Multiple return statements in a function.
On Thu, Apr 23, 2009 at 08:12:47AM -0400, Peter van der Does wrote:
> I tend to put my return value in a variable and at the end of the
> function I have 1 return statement.
> I have seen others doing returns in the middle of the function.
>
> Example how I do it:
> function check($a) {
> $return='';
> if ( is_array( $a ) ) {
> $return='Array';
> } else {
> $return='Not Array';
> }
> return $return;
> }
>
> Example of the other method:
> function check($a) {
>
> if ( is_array( $a ) ) {
> return ('Array');
> } else {
> return ('Not Array');
> }
> }
>
> What is your take? And is there any benefit to either method?
As mentioned, this is a matter of style. However, in a lot of cases, in
order to get the return at the very end, it's necessary to put endless
if/else pairs in the function. That makes it hard to read the source.
I'm sure there are purists out there who would insist the single return
go at the end. But expediency and readability may dictate otherwise.
Paul
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Re: [PHP] Multiple return statements in a function.
At 8:12 AM -0400 4/23/09, Peter van der Does wrote: I tend to put my return value in a variable and at the end of the function I have 1 return statement. I have seen others doing returns in the middle of the function. -snip- What is your take? And is there any benefit to either method? Peter van der Does Peter: It's called "Structured programming" -- one way in and one way out of a function. There are, of course, exceptions where it might help others reviewing your code to see what's going on, such as returning a null value if the argument(s) provided are not suitable. But normally the rule is, do not provide an exit from a function in more than one place. The "benefit" is easier to read code. Cheers, tedd -- --- http://sperling.com http://ancientstones.com http://earthstones.com -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Multiple return statements in a function.
On Thu, Apr 23, 2009 at 8:25 AM, Per Jessen wrote:
> Peter van der Does wrote:
>
>> I tend to put my return value in a variable and at the end of the
>> function I have 1 return statement.
>> I have seen others doing returns in the middle of the function.
>>
>> Example how I do it:
>> function check($a) {
>> $return='';
>> if ( is_array( $a ) ) {
>> $return='Array';
>> } else {
>> $return='Not Array';
>> }
>> return $return;
>> }
>>
>> Example of the other method:
>> function check($a) {
>>
>> if ( is_array( $a ) ) {
>> return ('Array');
>> } else {
>> return ('Not Array');
>> }
>> }
>>
>> What is your take? And is there any benefit to either method?
>
> It's only about style and coding logic. In essence, all the return does
> is pop the previous IP off the stack and adjust the stack pointer. It
> doesn't matter where you do that.
>
>
> /Per
>
>
> --
> Per Jessen, Zürich (16.2°C)
>
>
> --
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>
>
That's an interesting subject that I've never considered.
I usually return immediately. For me, it makes the code easier to
read. I work with a number of other coders here and, if the result
isn't returned then I have to keep reading through the code to make
sure nothing else is done with it. However, when I see the 'return'
then I know we're done there.
That said, I often see questionable coding practices in use at work.
I follow this list (and try to read books about the technologies I
use) because I intend to develop good practices for myself. That in
mind, if anybody feels strongly about doing it the other way, I'd be
interested in understanding its benefits.
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Re: [PHP] Multiple return statements in a function.
Peter van der Does wrote:
> I tend to put my return value in a variable and at the end of the
> function I have 1 return statement.
> I have seen others doing returns in the middle of the function.
>
> Example how I do it:
> function check($a) {
> $return='';
> if ( is_array( $a ) ) {
> $return='Array';
> } else {
> $return='Not Array';
> }
> return $return;
> }
>
> Example of the other method:
> function check($a) {
>
> if ( is_array( $a ) ) {
> return ('Array');
> } else {
> return ('Not Array');
> }
> }
>
> What is your take? And is there any benefit to either method?
It's only about style and coding logic. In essence, all the return does
is pop the previous IP off the stack and adjust the stack pointer. It
doesn't matter where you do that.
/Per
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