Re: [PHP-DEV] Idea to extend language: Explicitly setting variablescope inside user defined function (longer)
Personally, I think that variable scope handling works great the way it
is--particularly if you turn on error reporting. This way you have to
explicitly declare that you will be accessing a global variable and
don't run the risk of messing things up without thinking about it.
You could argue that a bit of discipline could solve this problem--but
then again a bit of discipline also makes you use the scoping the way it
is and come away clean without any major problems!
--Mt.
On Mon, 2002-10-21 at 21:19, Hans Zaunere wrote:
--- Marco Tabini [EMAIL PROTECTED] wrote:
Well, you have to admit that the issue of variable scope is the first
thing that hits someone who approaches PHP for the first time and
comes from other backgrounds, like C or ASP!
Still, after one adapts to this apparent weirdness of scoping, it
tends to grow on you. I find that no scope inheritance gives me one
less thing to worry about when writing code...
While some of the scoping tricks proposed seem like potential overkill,
I've yearned for a way to explicitly declare a variable a
super-global. Sure, I can stick it in one of the predefined
super-globals, but that just seems wrong.
Something like:
super $avar;
would be very useful for large projects and wouldn't cause a lot of
harm otherwise.
Hans
Marco
On Sun, 2002-10-20 at 22:41, Rasmus Lerdorf wrote:
How in the world do you know that code will run faster ?
Implementing your suggestion would take quite a lot of changes to
the
internals of PHP. Instead of just a global and a current symbol
table, we
would now need basically an unlimited number of symbol tables and
every
variable lookup would become more complex. Ergo it would slow
things
down.
-Rasmus
On Mon, 21 Oct 2002, NTPT wrote:
Hi.
I have some idea and suggestion how to extend PHP language a bit
in some
way. That may probably lead to increasing of php flexibility,
allow more
modular coding to be done etc
My sugestion is simple:
Allow PHP programmer to explicitelly told , WHAT variable scope
will be
used inside user defined functions.
In the traditional approach (afaik , i use php 4.2.2 ), as is
described in
the manual of php there a diferent varable scopes for each
functions , only
syntax global $valuename ; can lead to use variables global.
This aproach
is traditional and well known and is sufficient for most tasks.(I
say
sufficient, not effective...). My idea is going a bit behind it.
I suggest to introduce new keyword(s) or function(s) into the
PHP language
definiton
(i suggest syntax like var_scope scope or var_scope(scope)
)
That keywords SHOULD be used in user defined functions to
EXPLICITLY
define, WHAT kind of variable scope will be used inside this
function.
scope can be either
'local' = it means, that all variables used in this function
have a local
scope only.(it means like traditional behavior of php and its
variable
scopes until now )
'global' = each variable used in the function is from global
scope. Similar
to global $variable_1,$variable_2... $each variable used
in the
main execution line of the script
'caller' or 'inherit' This is MOST USEFUL part of the idea .
Function
variable scope is the SAME as from where the function was called.
(if
functino bar(),with have var_scope set to 'caller', is called
from function
foo() it have the same variable scope as function foo(), almost
like the
code of function bar() was included (by include something )
somewhere
inside foo() )
A little example code for demonstrating idea of the syntax and
how it should
work:
*/
?
$a=10;
echo Varaible $a.$a;
.
$foo_output =foo();
echo brvalue returnded by foo() .$foooutput;
echo brvalue $a after calling foo() but before calling bar()
.$a;
$bar_output=bar();
echo brvalue returnded by bar() .$bar_output;
.
.
echo brvalue $a after calling bar() .$a;
function foo()
{
$a=20;
echo $a inside function foo() = .$a
/* $bar_inside foo = bar();
echo Variable $a inside function foo() after calling bar().$a;
*/
.
.
return $a;
}
function bar()
{
var_scope caller // we have the SAME variable scope as from
where we are
called
$a=100;
.
.
.
return $a;
}
?
this should return : (with comments behind // )
Varaible $a 10
$a inside function foo() = 20
value returnded by foo() 20
value $a after calling foo() but before calling bar() 10
value returnded by bar() 100
value $a after calling bar() 100 // var_scope is set to
'caller', so $a
in global scope is modified inside bar() the some
Re: [PHP-DEV] Idea to extend language: Explicitly setting variablescope inside user defined function (longer)
How in the world do you know that code will run faster ?
Implementing your suggestion would take quite a lot of changes to the
internals of PHP. Instead of just a global and a current symbol table, we
would now need basically an unlimited number of symbol tables and every
variable lookup would become more complex. Ergo it would slow things
down.
-Rasmus
On Mon, 21 Oct 2002, NTPT wrote:
Hi.
I have some idea and suggestion how to extend PHP language a bit in some
way. That may probably lead to increasing of php flexibility, allow more
modular coding to be done etc
My sugestion is simple:
Allow PHP programmer to explicitelly told , WHAT variable scope will be
used inside user defined functions.
In the traditional approach (afaik , i use php 4.2.2 ), as is described in
the manual of php there a diferent varable scopes for each functions , only
syntax global $valuename ; can lead to use variables global. This aproach
is traditional and well known and is sufficient for most tasks.(I say
sufficient, not effective...). My idea is going a bit behind it.
I suggest to introduce new keyword(s) or function(s) into the PHP language
definiton
(i suggest syntax like var_scope scope or var_scope(scope) )
That keywords SHOULD be used in user defined functions to EXPLICITLY
define, WHAT kind of variable scope will be used inside this function.
scope can be either
'local' = it means, that all variables used in this function have a local
scope only.(it means like traditional behavior of php and its variable
scopes until now )
'global' = each variable used in the function is from global scope. Similar
to global $variable_1,$variable_2... $each variable used in the
main execution line of the script
'caller' or 'inherit' This is MOST USEFUL part of the idea . Function
variable scope is the SAME as from where the function was called. (if
functino bar(),with have var_scope set to 'caller', is called from function
foo() it have the same variable scope as function foo(), almost like the
code of function bar() was included (by include something ) somewhere
inside foo() )
A little example code for demonstrating idea of the syntax and how it should
work:
*/
?
$a=10;
echo Varaible $a.$a;
.
$foo_output =foo();
echo brvalue returnded by foo() .$foooutput;
echo brvalue $a after calling foo() but before calling bar() .$a;
$bar_output=bar();
echo brvalue returnded by bar() .$bar_output;
.
.
echo brvalue $a after calling bar() .$a;
function foo()
{
$a=20;
echo $a inside function foo() = .$a
/* $bar_inside foo = bar();
echo Variable $a inside function foo() after calling bar().$a;
*/
.
.
return $a;
}
function bar()
{
var_scope caller // we have the SAME variable scope as from where we are
called
$a=100;
.
.
.
return $a;
}
?
this should return : (with comments behind // )
Varaible $a 10
$a inside function foo() = 20
value returnded by foo() 20
value $a after calling foo() but before calling bar() 10
value returnded by bar() 100
value $a after calling bar() 100 // var_scope is set to 'caller', so $a
in global scope is modified inside bar() the some way, as if global $a was
used )
if you uncomment lines in bar()
Varaible $a 10
$a inside function foo() = 20
Variable $a inside function foo() after calling bar() 100 // var_scope in
function bar() is set to caller, so $a IN SCOPE of foo() ONLY is modified
inside bar().
value returnded by foo() 100
value $a after calling foo() but before calling bar() 10 // var_scope in
function bar() is set to caller, so $a IN GLOBAL SCOPE is NOT modified
inside bar().
value returnded by bar() 100
value $a after calling bar() 100 // var_scope is set to caller, so $a in
global scope is modified inside bar() the some waz, as if global $a was used
For WHAT it could be useful ??
for example for writing a databaze extraction layer of any aplication.
common real life situations are similar like in this example code
(simplified and abstracted from real life code of PHP application I
currently write )
?
.
.
.
.
do something
.
.
.
// now you need a call subroutine
$something=foo('cats','dogs','horses');
.
$different=bar('mices','meat','gras');
.
.
.
.
function foo($data_1,$data_2,$data_3)
{
global $spojeni;
.
.
do something here with $data_1,$data_2,$data_3.
.
.
.
$sqlstring=select * from example_table where mouse_catching='$data1' AND
sniffing='$data_2' AND riding='$data_3'
$result=pg_exec($spojeni,$sqlstring);
// code, that validate if db done that we want, if select return exactly
one line or if there is a some data inconsistrency etc etc. The following
code (wery simplified snipplet from real life situation) is almost the same
inside many of the functions
if ($result)
{
$lines=pg_numrows($result);
if ($lines 1)
{
do something if we have
Re: [PHP-DEV] Idea to extend language: Explicitly setting variablescope inside user defined function (longer)
At 04:31 AM 10/21/2002 +0200, NTPT wrote: Hi. I have some idea and suggestion how to extend PHP language a bit in some way. That may probably lead to increasing of php flexibility, allow more modular coding to be done etc My sugestion is simple: Allow PHP programmer to explicitelly told , WHAT variable scope will be used inside user defined functions. In the traditional approach (afaik , i use php 4.2.2 ), as is described in the manual of php there a diferent varable scopes for each functions , only syntax global $valuename ; can lead to use variables global. This aproach is traditional and well known and is sufficient for most tasks.(I say sufficient, not effective...). My idea is going a bit behind it. I suggest to introduce new keyword(s) or function(s) into the PHP language definiton (i suggest syntax like var_scope scope or var_scope(scope) ) That keywords SHOULD be used in user defined functions to EXPLICITLY define, WHAT kind of variable scope will be used inside this function. scope can be either 'local' = it means, that all variables used in this function have a local scope only.(it means like traditional behavior of php and its variable scopes until now ) 'global' = each variable used in the function is from global scope. Similar to global $variable_1,$variable_2... $each variable used in the main execution line of the script 'caller' or 'inherit' This is MOST USEFUL part of the idea . Function variable scope is the SAME as from where the function was called. (if functino bar(),with have var_scope set to 'caller', is called from function foo() it have the same variable scope as function foo(), almost like the code of function bar() was included (by include something ) somewhere inside foo() ) I think having something like caller is very bad. It would mean that functions don't have any contracts anymore as they can start messing around with the callers symbol table. Andi -- PHP Development Mailing List http://www.php.net/ To unsubscribe, visit: http://www.php.net/unsub.php
