Force type for function?

[Hugh Oxford]

I know I can force a variable passed to a function to be an object of
class bar

eg

function foo(bar $bar_object)
{
//code
}

but can I force a variable to be of a certain type?

eg

function foo(int $bar_int)
{
//code
}

[Erwin Moller]

Hugh Oxford schreef:

I know I can force a variable passed to a function to be an object of
class bar

eg

function foo(bar $bar_object)
{
//code
}

but can I force a variable to be of a certain type?

eg

function foo(int $bar_int)
{
//code
}

Hi Hugh,

I am not aware of such a languageconstru ct.

You can of course test yourself what is passed:
function foo($bar_int){
if (!is_integer($b ar_int)){
trigger_error(" function foo accepts only integers.");
}
// code
}

For a list of all is_* checks:
http://nl3.php.net/manual/en/function.is-array.php
On the left pane you'll see them all: is_double, is_bool, etc.
is_double, is_real, is_float are all the same. ;-)

Regards,
Erwin Moller
--
=============== =============
Erwin Moller
Now dropping all postings from googlegroups.
Why? http://improve-usenet.org/
=============== =============

[Jerry Stuckle]

Hugh Oxford wrote:

I know I can force a variable passed to a function to be an object of
class bar

eg

function foo(bar $bar_object)
{
//code
}

but can I force a variable to be of a certain type?

eg

function foo(int $bar_int)
{
//code
}

You really can't. If you're using classes, you can require it to be an
object of a specific class, but not any of the basic types. PHP doesn't
support function overloading.

--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attgl obal.net
=============== ===

[Sjoerd]

On Aug 5, 12:23*pm, Hugh Oxford <[e-mail] mwrote:

but can I force a variable to be of a certain type?

Of course you have tried
function bla(int $i)
and found that it did not work. The manual says about this:
"Type Hints can only be of the object and array (since PHP 5.1) type.
Traditional type hinting with int and string isn't supported." (http://
nl.php.net/manual/en/language.oop5.t ypehinting.php)

However, you can do the following:

function bla($i) {
assert(is_numer ic($i));
...
}

[Gordon]

On Aug 5, 11:56 am, Sjoerd <sjoer...@gmail .comwrote:

On Aug 5, 12:23 pm, Hugh Oxford <[e-mail] mwrote:

but can I force a variable to be of a certain type?

Of course you have tried
function bla(int $i)
and found that it did not work. The manual says about this:
"Type Hints can only be of the object and array (since PHP 5.1) type.
Traditional type hinting with int and string isn't supported." (http://
nl.php.net/manual/en/language.oop5.t ypehinting.php)

However, you can do the following:

function bla($i) {
assert(is_numer ic($i));
...

}

From the PHP manual:

Assertions should be used as a debugging feature only. You may use
them for sanity-checks that test for conditions that should always be
TRUE and that indicate some programming errors if not or to check for
the presence of certain features like extension functions or certain
system limits and features.

Assertions should not be used for normal runtime operations like input
parameter checks. As a rule of thumb your code should always be able
to work correctly if assertion checking is not activated.

A better approach would be:

function bla($i) {
if (is_numeric($i) )
{
...
}
}

[C. (http://symcbean.blogspot.com/)]

On Aug 5, 5:17 pm, Gordon <gordon.mc...@n tlworld.comwrot e:

On Aug 5, 11:56 am, Sjoerd <sjoer...@gmail .comwrote:

On Aug 5, 12:23 pm, Hugh Oxford <[e-mail] mwrote:

but can I force a variable to be of a certain type?

Of course you have tried
function bla(int $i)
and found that it did not work. The manual says about this:
"Type Hints can only be of the object and array (since PHP 5.1) type.
Traditional type hinting with int and string isn't supported." (http://
nl.php.net/manual/en/language.oop5.t ypehinting.php)

However, you can do the following:

function bla($i) {
assert(is_numer ic($i));
...

}

From the PHP manual:

Assertions should be used as a debugging feature only. You may use
them for sanity-checks that test for conditions that should always be
TRUE and that indicate some programming errors if not or to check for
the presence of certain features like extension functions or certain
system limits and features.

Assertions should not be used for normal runtime operations like input
parameter checks. As a rule of thumb your code should always be able
to work correctly if assertion checking is not activated.

A better approach would be:

function bla($i) {
if (is_numeric($i) )
{
...
}

}

Yes - this rather looks like you are creating errors instead of
handling them. If you really want your PHP to behave like a strongly
typed language then have a look at PHPlint, but really the solution is
to understand how dynamic typing works and apply that as part of the
validation at the point where data enters and leaves your code.

C.

[Lawrence Krubner]

Gordon wrote:

On Aug 5, 11:56 am, Sjoerd <sjoer...@gmail .comwrote:

>On Aug 5, 12:23 pm, Hugh Oxford <[e-mail] mwrote:

>>but can I force a variable to be of a certain type?

Of course you have tried
function bla(int $i)
and found that it did not work. The manual says about this:
"Type Hints can only be of the object and array (since PHP 5.1) type.
Traditional type hinting with int and string isn't supported." (http://
nl.php.net/manual/en/language.oop5.t ypehinting.php)

However, you can do the following:

function bla($i) {
assert(is_numer ic($i));
...

}

From the PHP manual:

Assertions should be used as a debugging feature only. You may use
them for sanity-checks that test for conditions that should always be
TRUE and that indicate some programming errors if not or to check for
the presence of certain features like extension functions or certain
system limits and features.

Assertions should not be used for normal runtime operations like input
parameter checks. As a rule of thumb your code should always be able
to work correctly if assertion checking is not activated.

A better approach would be:

function bla($i) {
if (is_numeric($i) )
{
...
}
}

Gordon,

What is the URL of the quote above from the manual?

Before I started doing unit tests, my code was full of such assertions,
used for error checking. I'm wondering what the argument against using
them was?

I mean, yes, they are for debugging, but at least for the projects I was
working on, we were forever debugging.
-- lawrence

[Jerry Stuckle]

Lawrence Krubner wrote:

Gordon wrote:

>On Aug 5, 11:56 am, Sjoerd <sjoer...@gmail .comwrote:

>>On Aug 5, 12:23 pm, Hugh Oxford <[e-mail] mwrote:

but can I force a variable to be of a certain type?
Of course you have tried
function bla(int $i)
and found that it did not work. The manual says about this:
"Type Hints can only be of the object and array (since PHP 5.1) type.
Traditional type hinting with int and string isn't supported." (http://
nl.php.net/manual/en/language.oop5.t ypehinting.php)

However, you can do the following:

function bla($i) {
assert(is_numer ic($i));
...

}

From the PHP manual:

Assertions should be used as a debugging feature only. You may use
them for sanity-checks that test for conditions that should always be
TRUE and that indicate some programming errors if not or to check for
the presence of certain features like extension functions or certain
system limits and features.

Assertions should not be used for normal runtime operations like input
parameter checks. As a rule of thumb your code should always be able
to work correctly if assertion checking is not activated.

A better approach would be:

function bla($i) {
if (is_numeric($i) )
{
...
}
}

Gordon,

What is the URL of the quote above from the manual?

Before I started doing unit tests, my code was full of such assertions,
used for error checking. I'm wondering what the argument against using
them was?

I mean, yes, they are for debugging, but at least for the projects I was
working on, we were forever debugging.
-- lawrence

Did you even look at the manual - like maybe under assert()?

And no, it's not a good idea to leave such code in the system. It
causes unnecessary overhead during normal operation. Also, depending on
the assert_options( ) setting, the script could terminate prematurely -
ok in a test environment but not a live one.

And if you have a good design and quality code to start with, you won't
be "forever debugging". But too many projects don't even have a design
to start - just some nebulous idea of what they want. So you don't
stand a chance, even if you have good programmers.

--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attgl obal.net
=============== ===

[Gordon]

On Aug 7, 8:06 am, Lawrence Krubner <lawre...@krubn er.comwrote:

Gordon wrote:

On Aug 5, 11:56 am, Sjoerd <sjoer...@gmail .comwrote:

On Aug 5, 12:23 pm, Hugh Oxford <[e-mail] mwrote:

>but can I force a variable to be of a certain type?
Of course you have tried
function bla(int $i)
and found that it did not work. The manual says about this:
"Type Hints can only be of the object and array (since PHP 5.1) type.
Traditional type hinting with int and string isn't supported." (http://
nl.php.net/manual/en/language.oop5.t ypehinting.php)

However, you can do the following:

function bla($i) {
assert(is_numer ic($i));
...

}

From the PHP manual:

Assertions should be used as a debugging feature only. You may use
them for sanity-checks that test for conditions that should always be
TRUE and that indicate some programming errors if not or to check for
the presence of certain features like extension functions or certain
system limits and features.

Assertions should not be used for normal runtime operations like input
parameter checks. As a rule of thumb your code should always be able
to work correctly if assertion checking is not activated.

A better approach would be:

function bla($i) {
if (is_numeric($i) )
{
...
}
}

Gordon,

What is the URL of the quote above from the manual?

Before I started doing unit tests, my code was full of such assertions,
used for error checking. I'm wondering what the argument against using
them was?

I mean, yes, they are for debugging, but at least for the projects I was
working on, we were forever debugging.

-- lawrence

http://www.php.net/assert