note
broquaint
<i>> how exactly do I define (rather than declare) a global variable in Perl</i><br>
The closest thing to a global variable are either "magical" variables or punctuation variables. Check out [id://141331|this node] for more info on globals.<p>
<i>> is there any kind of "super" use strict, which helps me catch typos that my programs may have?</i><br>
One of the reasons for using strict is to encourage the use of lexical variables and to move away from globals, which are can be a large cause of confusion to [perlman:perltrap|the unwary].<p>
<i>> is there any way of defining a variable like C's static (i.e., a global variable with local scope)</i><br>
Not really. You can use a global variable in a local scope using the <tt>[perlfunc:local|local()]</tt> function.
<code>
# use strict;
$foo = "a string";
sub bar {
local $foo;
print qq(foo is now localized and empty "$foo"\n);
}
</code>
Or you could use a [closure] to create the imitation of a static variable
<code>
{ # creates a new lexical scope
my $foo = "add text here - ";
sub add_text {
my $args = join '', @_;
$foo .= $args;
return $foo;
}
} # $foo now only referenced by &add_text
</code>
<i>> In fact, I have trouble understanding the difference between our ($i); and use vars qw($i);</i><br>
The difference is that <tt>[perldoc://our|our()]</tt> declares the variable into the current package and is visible for the rest of the lexical scope (in my opinion this is very icky and kinda anti-DWIM). Whereas <tt>use vars qw($x @y %z)</tt> just declares it's arguments into the current package, and doesn't mess with the lexical scope.
<br>
HTH
<p>
broquaint
<p>
<small>Update: changed explanation of <tt>[perldoc://our|our()]</tt> vs <tt>use vars qw($x @y %z)</tt> per [rob_au|rob_au's] [id://149326|note]. Also realised why [tilly] has been knocking <tt>[perldoc://our|our()]</tt> for so long ;-)</small><br>
<small>Update 2: also changed explanation of global variables per [shotgunefx|shotgunefx's] [id://149327|note]. /me thinks more research before posting might be an idea ...</small>
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