Classes and functions

flipis

Now, this must be a VERY stupid question, but i would like it answered if possible.

Can i make a function that returns a class?

Probably not, but...

I am VERY used to C structs, and for multiple results from a database query, i would like the functions to return a struct. But there are no structs in PHP, aren't they?

The other way is to return a bi-dimensional array, but i have to "cut" it in smaller arrays, and i CAN'T make a function to cut them all and then return them ALL at once.

The other alternative was to pass the arrays by reference in the functions, instead of passing by value, but it seems that passing arguments by reference will soon be deprecated in PHP.

So, any solution to my problem? I only need a function to return a class, a struct or an union.

Well, i said it was a stupid question. Nonetheless, i would like it answered.

Thanks very much in advance.

fLIPIS

"Do it or don't. But don't just try"

                -- Yoda --

[deleted]

You can create objects and pass them to a function as arguments, and functions can return objects.
You can even create an object inside a function and return that.

But more to the point: what on earth are you trying to do exactly? (besides doing things the way you are used to in C)

And where did you read that passing by reference will be depricated?

flipis

Thanks very much for the support. I'll try to explain myself a bit better.

Say we have this query:

$Query=mysql_query("SELECT a,b,c FROM d", $Connection);

So, i want 3 fields, but each field will return more than one result.

So i can do this following things:

A) Return 3 unidimensional arrays (i CAN'T do that from a function) containing the results. Functions can only have ONE return instruction (or so i think)

😎 Return 1 bidimensional array and then cut it into 3 unidimensional arrays.

C) Create a STRUCT with three arrays in it and make the function return that.

D) Create a data-only class, whose properties would be three arrays, and return it from the function.

E) Pass the three unidimensional arrays by reference and make the function modify them.

I don't know how to do the pass C, D, or E.

That is what i wanted someone to explain me.

And about the deprecation of reference passing, when i used &$whatever as an argument for a function, it gave me back a warning saying that passing by reference will soon be deprecated.

Maybe i have to declare the function like this:

function A(&$whatever){
.........
}

But i have ANOTHER problem. If i declare ONE argument as an agument passed by reference to the function, how can i declare more than one dynamically?

I'll explain this:

$Query=mysql_query("SELECT a,b,c FROM d", $Connection);

So i know i need three arrays.
I could declare the function like this:

function A(&$field_1, &$field_2, &$field_3){
............
}

where $field_1, $field_2, and $field_3 would be the arrays that would contain the results from the query.

But, if say i need FOUR arrays, how can i make the function declaration so it knows how many arguments i'm going to pass?

Maybe using some global PHP variable?

That is my problem.

Excuse my bad english, but i am spanish and this is not my native language.

And thanks very much for your support.

fLIPIS

[deleted]

A-E: a query returns rows, not columns.

Instead of working with three columns, you should work with X rows that have three values each. You can access these values directly from the resultset.

If you want you can create a function that will generate an array containing one array for each row.

About passing dynamic parameters: that is very very VERY bad programming, don't do it.

About passing by reference: adding the & in the function call is depricated, you must now add the & in the function definition, but the result is the same.

About your english: it's just fine.

flipis

A-E: a query returns rows, not columns.

Working 9 hours a day with PHP and MySQL makes my head dizzy. You're right.

Instead of working with three columns, you should work with X rows that have three values each. You can access these values directly from the resultset.

Brb.Ok.

About passing dynamic parameters: that is very very VERY bad programming, don't do it.

Why is that so bad?

About passing by reference: adding the & in the function call is depricated, you must now add the & in the function definition, but the result is the same.

Oh. Didn't know.

About your english: it's just fine

Well, thanks.

[deleted]

About passing dynamic parameters: that is very very VERY bad programming, don't do it.

Why is that so bad?

In your particular case it might not be so bad because you just give X times the same type of data. But for 'normal' parameters it is very very bad.

Many people use 'variable parameters' because they are lazy and they don't want to add all the parameters in every function call.

But the problem is that you can only leave parameters out at the end of the argument list.

if you define a function as

myfunc(a,b,c,d);

you can call it as
myfunc(a,b)
and
myfunc(a,b,c);
but not as
myfunc(a,c,d)
because that will be interpreted as
myfunc(a,b,c)

So all the 'optional' arguments must be on the right, and all the 'required' arguments on the left.

Now what do you do if you want to use
myfunc(a,d)?

well you must give all the parameters between a and d, so you end up giving all the parameters.

And then, there is no point in leaving out parameters anymore.

Plus, if you allow variable parameters, you script must not only check to see wether the parameters contain valid data (data that the function can work with) but it must also check to see which parameters it received.
So all the time you saved by typing less arguments is lost 100x by a slower script.

And ofcourse, if you read the script and you see 5 calls to the same function with a different number of arguments every time... how are you going to understand any of it?

A forum, a FAQ, what else do you need?