... Is that possible too? returning the variable if my was declared in that subroutine? and still keeping that attribute?
Yes, it's possible to return a value from a subroutine. I'll assume you do want to retain the "strict" pragma, and I'll work on the short testcases. Hopefully, you'll find it easy to extend it to your script.
Note the rules -
(1) "my" variable inside an if block is local to that if block and you cannot access it outside the block.
(2) "my" variable inside a subroutine will be local to that subroutine, and you cannot access it outside the subroutine.
(3) If your subroutine has a "my" variable $x, then you can declare a variable $x outside the subroutine, but its scope will be different. Which means, it is not the same variable as the one inside the function. You will have to: return the value from the subroutine, assign the value to the outer variable and then you'll have the same value.
Use the "return" statement to return a value from a Perl subroutine:
Code:
$
$
$ cat -n blub8.pl
1 #!/usr/bin/perl
2 use strict;
3 my $x = Config_Loader();
4 print "Outside the function: $x\n";
5 sub Config_Loader {
6 $_ = "ABC123XYZ";
7 if (/ABC(123)XYZ/){
8 my $x = $1;
9 print "Inside the function: $x\n";
10 return $x;
11 }
12 }
$
$ perl blub8.pl
Inside the function: 123
Outside the function: 123
$
$
Note the scope above. I used "return" inside the if block because "my" variable was inside the if block, and I could access it over there.
Note what happens if "return" is outside the if block -
Code:
$
$
$ cat -n blub9.pl
1 #!/usr/bin/perl
2 use strict;
3 my $x = Config_Loader();
4 print "Outside the function: $x\n";
5 sub Config_Loader {
6 $_ = "ABC123XYZ";
7 if (/ABC(123)XYZ/){
8 my $x = $1;
9 print "Inside the function: $x\n";
10 }
11 return $x;
12 # won't work because $x is local to if block
13 # and was discarded at the closing brace at line 10
14 # BUT, "strict" won't complain because a GLOBAL $x
15 # has already been declared, so $x at line 11 isn't
16 # "without scope".
17 }
$
$ perl blub9.pl
Inside the function: 123
Outside the function:
$
$
So, if you declare "my" local to the subroutine, rather than the if block, then you can also return from outside the if block -
Code:
$
$
$ cat -n blub10.pl
1 #!/usr/bin/perl
2 use strict;
3 my $x = Config_Loader();
4 print "Outside the function: $x\n";
5 sub Config_Loader {
6 my $x;
7 $_ = "ABC123XYZ";
8 if (/ABC(123)XYZ/){
9 $x = $1;
10 print "Inside the function: $x\n";
11 }
12 return $x;
13 # works because $x is local to subroutine
14 # and not the if block; it's available at line 12
15 }
$
$ perl blub10.pl
Inside the function: 123
Outside the function: 123
$
$
Using the same variable name inside and outside the function may not be easy on the maintainers of your code though. Use different names thusly -
Code:
$
$
$ cat -n blub11.pl
1 #!/usr/bin/perl
2 use strict;
3 my $y = Config_Loader();
4 print "Outside the function: $y\n";
5 sub Config_Loader {
6 my $x;
7 $_ = "ABC123XYZ";
8 if (/ABC(123)XYZ/){
9 $x = $1;
10 print "Inside the function: $x\n";
11 }
12 return $x;
13 # works because $x is local to subroutine
14 # and not the if block; it's available at line 12
15 }
$
$ perl blub11.pl
Inside the function: 123
Outside the function: 123
$
$
Note that if you do not add "use strict" pragma, you can still use "my" for the variable inside the subroutine, and return its value to a similarly named variable outside the subroutine -
Code:
$
$
$ cat -n blub12.pl
1 #!/usr/bin/perl
2 $x = Config_Loader();
3 print "Outside the function: $x\n";
4 sub Config_Loader {
5 my $x;
6 $_ = "ABC123XYZ";
7 if (/ABC(123)XYZ/){
8 $x = $1;
9 print "Inside the function: $x\n";
10 }
11 return $x;
12 }
$
$ perl blub12.pl
Inside the function: 123
Outside the function: 123
$
$
Once again, note that the variable declared at line 2 is not the same as the variable declared at line 5.
It just happens to have the same name. The reason I am able to display the value "123" at line 3 is because the "outer" $x was assigned the value of the "inner" $x at line 2.
So, what happens if the "outer" $x is not assigned the value at line 2 ? Can you still access the value of the "inner" $x ?
If you've understood everything till here, you'll know that it won't work.
Code:
$
$
$ cat -n blub13.pl
1 #!/usr/bin/perl
2 Config_Loader(); # function was invoked, but return value was not assigned
3 print "Outside the function: $x\n"; # Sorry, $x is unknown here because $x of the subroutine was discarded at line 12
4 sub Config_Loader {
5 my $x;
6 $_ = "ABC123XYZ";
7 if (/ABC(123)XYZ/){
8 $x = $1;
9 print "Inside the function: $x\n";
10 }
11 return $x;
12 }
$
$ perl blub13.pl
Inside the function: 123
Outside the function:
$
$
HTH,
tyler_durden
---------- Post updated at 03:49 PM ---------- Previous update was at 02:41 PM ----------
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