use of constants in an interpreter environment

[Water Cooler v2]

what's the use of having constants in an interpreted language like
php, when there's no compile cycle?

Other than enforcing programmer discipline or affording a convinience
for the programmers, I don't see any.

php gurus tell.

[Rik]

On Tue, 14 Aug 2007 22:49:50 +0200, Water Cooler v2 <wt*****@yahoo.com>
wrote:

what's the use of having constants in an interpreted language like
php, when there's no compile cycle?

Other than enforcing programmer discipline or affording a convinience
for the programmers, I don't see any.

1. Constants cannot be changed, overwritten, or unset (either deliberately
or by accident). Certainly on projects with more programmers this really
pays off.

2. Constants are always in scope.

Then again, that's all about enforcing discipline and convenience
offcourse.
--
Rik Wasmus

[Water Cooler v2]

2. Constants are always in scope.

You mean I can't have a global constant? Hmm! There's no syntax for
it.

global define ("foo", "bar");

[Rik]

On Tue, 14 Aug 2007 23:01:54 +0200, Water Cooler v2 <wt*****@yahoo.com
wrote:

>2. Constants are always in scope.

You mean I can't have a global constant? Hmm! There's no syntax for
it.

No, exactly the opposite: constants are kind of 'superglobals': they are
always in scope, in every include, function, method etc. they can be used.

<?php
define('FOO','bar');
$foz = 'baz';
function test(){
echo FOO;
echo $foz;
}
test();
?>
--
Rik Wasmus

[Water Cooler v2]

<?php
define('FOO','bar');
$foz = 'baz';
function test(){
echo FOO;
echo $foz;}

test();
?>

I tried it on my machine. Shows a blank page. Is your argument that
variables are limited by scope whereas constants have global (and not
superglobal) scope?

[Rik]

On Tue, 14 Aug 2007 23:14:40 +0200, Water Cooler v2 <wt*****@yahoo.com
wrote:

>

><?php
define('FOO','bar');
$foz = 'baz';
function test(){
echo FOO;
echo $foz;}

test();
?>

I tried it on my machine. Shows a blank page.

There's something wrong with your machine. It should return 'bar',
followed by either nothing or an error message $foz is not defined,
depending on error settings.

Is your argument that
variables are limited by scope whereas constants have global (and not
superglobal) scope?

The term 'superglobal' indicates that a constant is automatically
global--i.e., automatically available in every scope, without the use of
either the global keyword or the $GLOBALS array. A variable can be global,
PHP has some variable superglobals (like $_SERVER,$_POST,$_GET, etc.), but
there is no way to make a normal user-defined variable a superglobal.
Putting variables in global scope (so not available in any scope, just the
global) it pretty easy, so easy it's done to death is scripts of starters.
--
Rik Wasmus

[gosha bine]

On 14.08.2007 22:49 Water Cooler v2 wrote:

what's the use of having constants in an interpreted language like
php, when there's no compile cycle?

php is not an interpreted language in a strict sense, it's first
compiled to bytecodes and then executed.

>
Other than enforcing programmer discipline or affording a convinience
for the programmers, I don't see any.

Programming languages are all about discipline and convenience.
Otherwise, we would be still programming in machine codes like 50 years ago.

--
gosha bine

makrell ~ http://www.tagarga.com/blok/makrell
php done right ;) http://code.google.com/p/pihipi

[Toby A Inkster]

Rik wrote:

there is no way to make a normal user-defined variable a superglobal.

Except the PHP runkit extension.

--
Toby A Inkster BSc (Hons) ARCS
[Geek of HTML/SQL/Perl/PHP/Python/Apache/Linux]
[OS: Linux 2.6.12-12mdksmp, up 55 days, 12:04.]

Fake Steve is Dead; Long Live Fake Bob!
http://tobyinkster.co.uk/blog/2007/08/13/fake-bob/