Lazy instancing (?)

jezze

Lets say I have a simple string:

$name = "John";
$str = "Hello " . $name . "!";
/* code ......

$name = "Peter" // ??????

..... code */
echo($str);

Is it possible for me to change the $name variable into "Peter" somewhere within the code segment so when arriving at the echo it would print "Hello Peter!" instead?

bradgrafelman

Short answer is: no.

On the second line of your example code, $str is initialized with the vale "Hello John!" because it copies the value of $name into its value. The two variables are in no way linked to each other.

The quickest alternative I can think of would be to use a function instead:

function greet($name) {
    return "Hello $name!";
}

$name = "Peter";
echo greet($name);
$name = "John";
echo greet($name);

stevesweetland

yeah you could do that, but not with 'echo', with printf.

$name = "John";
$str = "Hello %s!";

printf($str,$name); // would output "Hello John!;

$name = "Peter";

printf($str,$name) // would output "Hello Peter!";

i figure..

laserlight

I do not think that really works out to what the OP requested, stevesweetland. After all, in your example $name is used in the printf() call, but for the OP's example $name is not used when printing. The equivalent code with echo for your example is:

$name = "John";
$str = "Hello ";

echo $str . $name; // would output "Hello John!;

$name = "Peter";

echo $str . $name; // would output "Hello Peter!";

jezze

Thanks for all the feedback!

Of course as you might guess the actual code I'm writing is alot more complicated than the example above which only works as an easier example of the actual problem I'm facing. But the %s gave me a few ideas and I think I might be able to solve my problem!

Thanx again

jezze

As a small note if anyone was interested:

I have a class DatabaseQuery which holds among other things the information associated to a specific SQL-query like what tables, columns, conditions et.c it should use.

I wanted a function, something like DatabaseQuery::getColumnValue($name), that would be placed a bit of everywhere in a PHP-file which would return the value of a particular column defined by the DatabaseQuery instance.

What I wanted was that instead of defining all the columns available in class DatabaseQuery beforehand I wanted the getColumn function to dynamically add itself to the list of columns that should be fetched from the database and fetch all of them in one go. The problem is that the columns' values can not be used because the values has not yet been fetched and therefor are empty. I just thought it would be cool to not have to fetch the information beforehand (before knowing which columns would actually be used) but instead only fetch the ones actually used. It's not really a problem it would just be a cool thing to do.

stevesweetland

laserlight wrote:
I do not think that really works out to what the OP requested, stevesweetland. After all, in your example $name is used in the printf() call, but for the OP's example $name is not used when printing. The equivalent code with echo for your example is:
$name = "John";
$str = "Hello ";

echo $str . $name; // would output "Hello John!;

$name = "Peter";

echo $str . $name; // would output "Hello Peter!";

im aware of that, but hed already shown he knows how to append variables together, in his code, so i figured id show him another option... pointless me showing him his code in a different order, right?

jezze... it sounds like you need to add a function to your class - you could presume in this function that the field supplied would be available and return all the values from that field - the only thing that would leave you to do would be to dump the whole mysql return into an array beforehand (perhaps?).

if... you're done with this post, can you mark it resolved... thanks