sub Func1 {
    do we have a num_var;
    do we have a name_var;
    do we have params (optional)

    is the num_var of number format
    is the name_var of name format

    ....

    other code
}

Func1($num_var, $name_var, %params);
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I know this is a little generic, but lets say most subroutines can take a generic number style argument and others take a generic string type argument I want to make sure thats all they are.
This will no doubt take the form of a reg exp checking its just a string (i.e. no :;"' etc. in it) and similarly for the number.
I'm sure there are *many* well written modules that take care of boundary conditions so what I'm wanting is the 'standard' code for doing these 'generic' tests so to speak i.e. the best practice bit of code for doing this? Do people generally generally just go;

Func1 {
    is number of args correct?

    check arg1 is a number and only a number with reg exp?
    check arg2 is a string and only a string with reg exp?
    ...

    other code
}
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or are there more elegant solutions that are generally used...something like?

sub CheckArgs {
    get number of args
    get args to check
    
    check we have the right number of args
    foreach arg check the type with the appropriate reg exp.

    return status.
}

sub Func1 {
    CheckArgs (2, @_, "NUM", "STRING");

    ....

    other code
}
sub Func2 {
    CheckArgs (3, @_, "STRING", "NUM", "STRING");

    ....

    other code
}
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Is the second sort of approach considered to weighty if you are wanting the code to be quite fast or is just checking each argument individually in each subroutine generally the practice as in there are no 'generic' inputs? I would appreciate any insights or code snippits on how others have satisfied boundary conditions.

Regards Paul.
Update: If you want an example subroutine to write something around here is one...
In this case it would just be $name that would need to be checked, and that we have a name...I'm just trying to think generically though.

sub add_output {
    #Create an unconnected named output
        my $self = shift;
    my $graph = $self->{graph};
    my $name = shift;
    my %params = @_;

    #Check for valid options
    foreach my $p ( keys %params ) {
        if ( !exists $valid_userconfigurable_vertex_params->{$p} ) {
            Carp::confess(sprintf "Unknown Option : $p");
        }
    }

    #Set the activation function
    my $activation;
    if ( exists $params{activation} ) {
        $activation = $params{activation};
    } else {
        $activation = "SIGMOID";
    }

    #Create the vertex
        $graph->set_vertex_attributes($name, {  id => GetNewVertexNumb
+er($self),
                        added_a_vertex => 1,
                                                allow_inputs => "Yes",
                                                allow_outputs => "No",
                                                activation => $activat
+ion,
                                                value => 0 });

    #Connect vertex to the bias vertex
    $graph->add_edge("BIAS", $name);

    #An update to the layout is required
    $graph->set_graph_attribute("update_layout", 1);
}
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2005-03-30 Janitored by Arunbear - added readmore tags, as per Monastery guidelines