local - perl to php

[rebecca]

Good Morning all,

in my perl script, I have a number of variables that are localised within a function - as in:

local($file);

so that a global variable will have a localised value - after the local is executed but before the scope is exited, any subroutines and executed formats will use the local value but then reverts to the original global value once the scope is exited (straight out of the manual).

Is there anything in php that will work in the same way. Any suggestion?

Thanks everybody,
Rebecca

[marcel]

by default all vars within a function are local'.
If you want to acces aglobal' var inside a function you have to declare it as `global'

function your_f()
{
global $a_global_var;

$other_var = 'something'; // this is local
...
}

PM

[rebecca]

um yes, thanks

but that's not /quite/ what I meant. I don't want a local variable . . . I want to locally act on a global variable, temporarily change the value of the global variable and then have it return to the original global variable value once this segment of code is finished.

This way (in perl) when a function containing this 'local (var1, var2)' is called within the main script, the global variables are changed for the main script but only until that part of the script and it's other subfunctions are ended.

more input? I'm can't find a function in php that does this and I'm sure the answer is really simple just the more I think about it the more confused I get.

thank-you for helping,
rebecca

[marcel]

now, i'm confused 🙂
i've try next perl script:

  1 #!/usr/bin/perl
  2 $\="\n";
  3 $b=1;
  4 sub sub_
  5 {
  6         local($b);
  7         print $b;
  8         $b=5;
  9         print $b;
 10 }
 11
 12 sub_();
 13 print $b;

the output is:

#########
[EMPTY LINE]
5
1
########
looks like in line 7 the value of `$b' is NULL

may be you have something like:
local ($var1, $var2) = @_;
in this case ($var1, $var2) are the parameters passed to the subrutine

in php you have to do just:
function fun_($var1, $var2)
{
...
// use $var1 , $var2
...
}

PM

[rebecca]

thank-you, that's very helpful :-)

so in perl I have:

sub do_file {
local($FILE) = @_;
local(@FILE);

. . .
@FILE = cdopenfile($FILE);
. . .
}

which would mean in php that I have:

function do_file($file){}
and then within the function I can create an array to hold cdopenfile($file).

Is that right?
Sorry, just graduated, new to perl, new to php and the first job I get is making me learn both at once. Which is good, but a bit stressful. I really appreciate the help :-)

[marcel]

almost right 🙂

in this case, in php you can not create an array in one statement

you should use
$fp=fopen($file);
and
$array_line[$i] = fgets($fp, $max_length)
in a loop
to get lines from the file, one by one..

other way is:
$all_content = fread ($fd, filesize ($file));
it's just one string...

good luck!

PM

[Anon]

IMO the best thing to do is just forget about 'local' entirely (it's one of the really nutso features of perl, and one you can easily do without.) Although PHP has a unique way of dealing with global vs local variables, it's fairly straightforward compared to Perl: if you need to access a global variable, you need to know its name--if you then want a private copy of that value, then just use a different name inside your function, e.g.:

$global = 1;

function sample()
{
global $global;
$private = $global + 77;
...
}

For what it's worth, the real justification for 'local' in Perl is all those magic/built-in variables, and PHP doesn't do that so the need for 'local' to act the same way as in Perl is non-existent.

[Anon]

One further FWIW--all that automatic/magic variable stuff in Perl is primarily there in support of terseness, which I guess helps you if you spend all your time writing quick little throwaway programs. But for code that really has to last (and be maintainable) readability is vastly more important than saving a few keystrokes.