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;
.
$foo_output =foo();
echo "<br>value returnded by foo() ".$foooutput;
echo "<br>value $a after calling foo() but before calling bar() ".$a;
$bar_output=bar();
echo "<br>value returnded by bar() ".$bar_output;
.
.
echo "<br>value $a after calling bar() ".$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 ($lines <1)
{
do something if we have no records. Typicaly display error message
,repeat quyery with default values etc.....
}
if ($lines >1)
{
oops, database is inconsistent. exactly one line should be returned. Stop
script
die("database EXAMPLE TABLE have data inconsistency. contact server
admin now")
}
if ($lines=1)
{
$retval= pg_fetch_array($result,0); // we have what we are looking for...
}
}
else
{
die("No select from example_table")
}
//end of the validating code
return $retval;
}
function bar($data_1,$data_2,$data_3)
{
global $spojeni;
$sqlstring="select * from other_example_table where bla bla bla ...... some
thuing'";
// bla bla bla and similar as in foo()
}
?>
in traditional approach, it could be done better and flexibile only by few
and limited ways.
One of then is to use for example include "" like this:
<?
function foo($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 exactlz
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
include "database_code.php" ; // all validating code is moved inside
database_code.php3 , so it could be uset more frequently in more functions ;
//end of the validating code
return $retval;
}
?>
but it have several caveats. For example , database_code.php can be a big
fat file with lot of lines and tests and if function foo() is called
somewhere from loop, it will be included each itteration and it menas,
that in each iterration will be parsed for errors (fix me if i am wrong...)
etc etc and loop can have hunderds or thousends itteration and i iffraid, it
could have a serious performance impact.
The code rewriten for using my suggested "explicitly setiing of variable
scope inside function" language extension, exactly "var_scope caller;" will
look like this ( the following example uses "get_var_scope()" function, that
is part of the sugested extensions to examine WHAT variable scope we are
currently have and "local_vars $varname" (with list variables, that are
intendet to be LOCAL ONLY , it act like oposite of "globals") ) :
<?
$database="postgres";
.
.
.
.
do something
.
.
.
// now zou need a call subroutine
$something=foo('cats','dogs','horses');
.
$different=bar('mices','meat','gras');
.
.
.
.
function foo($data_1,$data_2,$data_3)
{
global $spojeni,$database;
.
.
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'"
$retval= db_execute_query($sqlsting);
return $retval;
}
function bar($data_1,$data_2,$data_3)
{
global $spojeni;
$sqlstring="select * from other_example_table where mouse_catching='$data1'
AND sniffing='$data_2' AND riding='$data_3'";
$retval= db_execute_query($sqlsting);
return $retval;
}
function db_execute_query($sqlstring)
{
// executing database query, making all tests that everything went good
etc... simple database abstraction layer included as bonus :o) ......
var_scope caller; // ve inherit variable scope from where we are called
global $database; // we need name of the database engine
local_vars $i,$j,$k,$partial_result,$retval,$sqlstring ; // good for loop
counters, like for($i=0;$i<something;$i++),parameters and retvals, to do
not harmly interfere with function from we are called .it has opposite
meaning to "globals"
$caller_name=get_var_scope(); // we need to know from where we are called
do construct error messages
if ($database=="postgres")
{
// database postgres specific code
$result=pg_exec($spojeni,$sqlstring);
if ($result)
{
$lines=pg_numrows($result);
if ($lines <1)
{
do something if we have no records. Typicaly display error message
}
if ($lines >1)
{
oops, database is inconsistent. Stop script
die("database inconsistency in function." .$caller_name." contact
server admin now")
}
if ($lines==1)
{
$retval= pg_fetch_array($result,0); // we have what we are looking
for...
}
}
else
{
die("No select from example_table in ".$caller_name)
}
}
if ($database=="mysql")
{
// mysql specific code
}
etc etc etc.......
return $retval;
}
?>
in the following example, simple and very "good readable" code is created,
with is smaller, flexibile and simple to underestand and i expect, it will
run faster.
I thing, that my sugested langue extension can lead to more flexibile coding
style, allow to bulid modular programs far better, increse readibility of
php code and may lead to smaller and faster php programs in some very
common situations. So may be useful to add it to php language.
Abstract:
Suggestion of adding capability "Explicit setting of variable scope inside
user defined functions".
adding "var_scope local", "var_scope global", and most useful "var_scope
caller" to explicitly set, what variable scope will be used inside user
defined function.Some supporting keywords and functions suggested too.
keyword "local_vars variable list" as oposite for "globals" to avoid
harm interference of private function varibles with variables of its
caller and function "get_var_scope()" to detect, witch variable scope is
currently used. I hope that this extension can lead to flexibile, shorter
and faster PHP code in common situations and is "worth of implementation"
Thanx for reading my letter and i appologize for wasting your time (if
any).And execuse my bed english;
NTPT
---
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