Well, taking your question literally, it's simply:
$class_name = "Calvin::Hobbes"; # from some value above
my $new_object = $class_name->new;
There's no magic involved in using a string as a classname.
But perhaps you also intend to dynamically load a require file. In which case,
I'd do something like this:
if (grep $class_name eq $_, qw(Calvin::Hobbes Peter::Gabriel Dog::Day:
+:Afternoon)) {
# must validate the name, or security holes will run rampant
eval "require $class_name"; die $@ if $@;
$object = $class_name->new;
}
Notice the validation there. Essential. Without that, damage will result. Use whatever mechanism you want, but it must match one of the names you are expecting, and certainly not one of the names you are not.
Also, this approach presumes a constant constructor called new. That's
not necessarily the case, since Perl doesn't require any constructor called new to be defined. In that case, you'll want a table, like:
my %make_a = qw(
Calvin::Hobbes new
Peter::Gabriel play
Dog::Day::Afternoon watch
);
...
if (my $constructor = $make_a{$class_name}) {
unless ($INC{$class_name}) {
eval "require $class_name"; die $@ if $@;
}
$object = $class_name->$constructor();
}
The nice thing about this approach is that the table of "how" is automatically
the validation table for "permitted".
-- Randal L. Schwartz, Perl hacker
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.