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Re: Declaring an array necessary?

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On 2/21/14 9:56 AM, The Natural Philosopher wrote:
> I was just wondering. Php assumes a varibale exists as soon as it is
> assigned a value, but a function exists to create an array..
> Sop can one just say
>
> $arr['hello']='sexy';
>
> or should there be
>
> $arr=array();
>
> first?
>
>

Necessary, no, but it is still a best practice.  It helps with 
maintenance later, as well as it clearly states your intent.

Imagine this scenario: You start with

function createMyArray($someData) {

   $arr['theData'] = $someData->getX();
   $arr['theOtherData'] = $someData->getY();

   return $arr;
}


A few weeks later, you get a bug report that you need to only sometimes 
add getX().

function createMyArray($someData) {

   if ($someData->isFoo()) {
     $arr['theData'] = $someData->getX();
   }
   $arr['theOtherData'] = $someData->getY();

   return $arr;
}

Then, you (or someone else) finds out getY() is optional...


function createMyArray($someData) {

   if ($someData->isFoo()) {
     $arr['theData'] = $someData->getX();
   }
   if ($someData->isBar()) {
     $arr['theOtherData'] = $someData->getY();
   }

   return $arr;
}


Oh no! You've just introduced a bug where if isFoo and isBar returns 
true, then $arr is not set!


Now, if the original author had just added "$arr = []"; things would 
have never progressed to this state.  It's called defensive programming. 
Doing certain things you know aren't strictly necessary now, but might 
be necessary, or clear up possible confusion.

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Thread

Declaring an array necessary? The Natural Philosopher <tnp@invalid.invalid> - 2014-02-21 17:56 +0000
  Re: Declaring an array necessary? Christian Stadler <stadli@gmx.de> - 2014-02-21 21:04 +0100
    Re: Declaring an array necessary? Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-21 15:48 -0500
    Re: Declaring an array necessary? The Natural Philosopher <tnp@invalid.invalid> - 2014-02-21 21:32 +0000
      Re: Declaring an array necessary? Gregor Kofler <usenet@gregorkofler.com> - 2014-02-21 22:55 +0100
        Re: Declaring an array necessary? Tim Streater <timstreater@greenbee.net> - 2014-02-21 22:06 +0000
  Re: Declaring an array necessary? "M. Strobel" <sorry_no_mail_here@nowhere.dee> - 2014-02-21 22:58 +0100
  Re: Declaring an array necessary? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2014-02-21 14:03 -0800

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