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Manual Reference Pages  -  MAIL::BULKMAIL::OBJECT (3)

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Mail::Bulkmail::Object - used to create subclasses for Mail::Bulkmail.



Jim Thomason,


Older versions of this code used to be contained within the Mail::Bulkmail package itself, but since 3.00 now has all of the code compartmentalized, I couldn’t leave this in there. Well, technically I *could*, but I didn’t like that. It’s wasteful to make Mail::Bulkmail::Server a subclass of Mail::Bulkmail, for instance, since they don’t share any methods, attributes, whatever. Well, none beyond the standard object methods that I like to use. Hence this module was born.

Of course, you don’t have to use this to create subclasses, but you’ll run the risk of making something with an inconsistent interface vs. the rest of the system. That’ll confuse people and make them unhappy. So I recommend subclassing off of here to be consistent. Of course, you may not like these objects, but they do work well and are consistent. Consistency is very important in interface design, IMHO.


You’ll need to specify your conf files. There is the @conf_files array, toss in as many conf files as you’d like

 my @conf_files = qw(

It’ll just silently ignore any conf files that aren’t present, so don’t expect any errors. That’s to allow you to place multiple conf files in for use on multiple servers and then not worry about them.

Multiple conf files are in significance order. So if mail.bulkmail.cfg and mail.bulkmail.cf2 both define a value for ’foo’, then the one in mail.bulkmail.cfg is used. And so on, conf files listed earlier are more important. There is no way for a program to later look at a less significant conf value.


conf_files conf_files returns your conf_files array.

 my @conf_files = $class->conf_files();

You can also programmatically add a new conf_file this way.

 $class->conf_files(/path/to/new/conf.file, /path/to/other/conf.file);      #, etc

However, it’d be better to specify your conf file at use time.

 use Mail::Bulkmail::Object 3.00 "/path/to/conf.file";

This also (naturally) works in all subclasses.

 use Mail::Bulkmail 3.00 "/path/to/conf.file";
 use Mail::Bulkmail::Dynamic 3.00 "/path/to/conf/file";

and so on.

Note that adding on via ->conf_files or importing puts onto the FRONT of the @conf_files array, i.e., those conf files are more significant.


 @conf_files = qw(/path/to/file /path/to/file2);

 use Mail::Bulkmail::Object 3.00 "/path/to/file3" "/path/to/file4";

 Mail::Bulkmail::Object->conf_files("/path/to/file5", "/path/to/file6");

 print Mail::Bulkmail::Object->conf_files;
        #prints out /path/to/file5 /path/to/file6 /path/to/file3 /path/to/file4 /path/to/file path/to/file2

Note that you don’t *need* conf files, you can still specify all information at construction time, or via mutators, or whatever. But a conf file can make your life a lot easier.

add_attr add_attr adds object attributes to the class.

Okay, now we’re going to get into some philosophy. First of all, let me state that I *love* Perl’s OO implementation. I usually get smacked upside the head when I say that, but I find it really easy to use, work with, manipulate, and so on. And there are things that you can do in Perl’s OO that you can’t in Java or C++ or the like. Perl, for example, can have *totally* private values that are completely inaccessible (lexicals, natch). private vars in the other languages can be redefined or tweaked or subclassed or otherwise gotten around in some form. Not Perl.

And I obviously just adore Perl anyway. I get funny looks when I tell people that I like perl so much because it works the way I think. That bothers people for some reason.

Anyway, as much as I like how it works, I don’t like the fact that there’s no consistent object type. An object is, of course, a blessed ((thingie)) (scalar, array, code, hash, etc) reference. And there are merits to using any of those things, depending upon the situation. Hashes are easy to work with and most similar to traditional objects.

 $object->{$attribute} = $value;

And whatnot. Arrays are much faster (typically 33% in tests I’ve done), but they suck to work with.

 $object->[15] = $value;        #the hell is 15?

  by the way, you can make this easier with variables defined to return the value, i.e.
  $object->[$attribute] = $value;       #assuming $attribute == 15

Scalars are speciality and coderefs are left to the magicians. Don’t get me wrong, coderefs as objects are nifty, but they can be tricky to work with.

So, I wanted a consistent interface. I’m not going to claim credit for this idea, since I think I originally read it in Object Oriented Programming in Perl (Damien’s book). In fact, I think the error reporting method I use was also originally detailed in there. Anyway, I liked it a lot and decided I’d implement my own version of it.

Basically, attributes are accessed and mutated via methods.


For all attributes. This way, the internal object can be whatever you’d like. I used to use mainly arrays for the speed boost, but lately I use hashes a lot because of the ease of dumping and reading the structure for debugging purposes. But, with this consistent interface of using methods to wrapper the attributes, I can change the implementation of the object (scalar, array, hash, code, whatever) up in this module and *nothing* else needs to change.

Say you implemented a giant system in OO perl. And you chose hashrefs as your object. But then you needed a big speed boost later, which you could easily get by going to arrays. You’d have to go through your code and change all instances of $object->{$attribute} to $object->[15] or whatever. That’s an awful lot of work.

With everything wrappered up this way, changes can be made in the super object class and then automagically populate out everywhere with no code changes. Spiffy stuff.

There are some disadvantages, there is a little more overhead for doing the additional method call, but it’s usually negligible. And you can’t do nice things like:

 youd have to do
 $object->attribute($object->attribute + 1);

Which is annoying. But I think it’s offset by the consistent interface regardless of what your underlying object is.

Enough with the philosophy, though. You need to know how this works.

It’s easy enough:

 package Some::Class;


Now your Some::Class objects have a foo attribute, which can be accessed as above. If called with a value, it’s the mutator which sets the attribute to the new value and returns the new value. If called without one, it’s the accessor which returns the value.

 my $obj = Some::Class->new();
 print $obj->foo();                     #prints bar
 print $obj->foo(boo);        #prints boo
 print $obj->foo();                     #prints boo

add_attr calls should only be in your module. <B>Never in your programB>. And they really should be defined up at the top.

Internally, an add_attr call creates a function inside your package of the name of the attribute which reflects through to the internal _accessor method which handles the mutating and accessing.

There is another syntax for add_attr, to define a different internal accessor:

 Some::Class->add_attr([foo, other_accessor]);

This creates method called ’foo’ which talks to a separate accessor, in this case other_accessor instead of going to _accessor. This is useful if you want to create a validating method on your attribute.

Additionally, it creates a normal method going to _accessor called ’_foo’, which is assumed to be the internal attribute slot your other accessor with use. In generall, for a given attribute, _attribute will be created for internal use.

other_accessor will get the object as the first arg (as always) and the name of the internal method as the second.


 Some::Class->add_attr([foo, other_accessor]);


 sub other_accessor {
        my $self        = shift;
        my $method      = shift;        # "_foo", in this example

        if (@_){
                my $val = shift;        # "bee", in this example
                if ($val == 7){
                        return $self->$method($val);
                else {
                        return $self->error("Cannot store must be 7!");
        else {
                return $self->$method();

And, finally, you can also pass in additional arguments as static args if desired.

 Some::Class->add_attr([foo, other_accessor], bar);


 sub other_accessor {
        my $self        = shift;
        my $method      = shift;
        my $static      = shift;        #bar in our example

        my $value       = shift;        #bee in our example

 All easy enough. Refer to any subclasses of this class for further examples.

add_class_attr This is similar to add_attr, but instead of adding object attributes, it adds class attributes. You <B>cannotB> have object and class attributes with the same name. This is by design. (error is a special case)

 Some::Class->add_attr(foo);                  #object attribute foo
 Some::Class->add_class_attr(bar):    #class attribute bar

 print $obj->foo();
 print Some::Class->bar();

Behaves the same as an object method added with add_attr, mutating with a value, accessing without one. Note that add_class_attr does not have the capability for additional internal methods or static values. If you want those on a class method, you’ll have to wrapper the class attribute yourself on a per case basis.

Note that you can access class attributes via an object (as expected), but it’s frowned upon since it may be confusing.

class attributes are automatically initialized to any values in the conf file upon adding, if present.

add_tricke_class_attr It’s things like this why I really love Perl.

add_trickle_class_attr behaves the same as add_class_attr with the addition that it will trickle the attribute down into any class as it is called. This is useful for subclasses.


 package SuperClass;


 package SubClass;
 @ISA = qw(SuperClass);

 print SubClass->foo();                 #prints bar
 print SuperClass->foo();               #prints bar

 print SuperClass->foo(baz);  #prints baz
 print SubClass->foo();                 #prints baz

 print SubClass->foo(dee);    #prints dee
 print SuperClass->foo();               #prints dee

See? The attribute is still stored in the super class, so changing it in a subclass changes it in the super class as well. Usually, this behavior is fine, but sometimes you don’t want that to happen. That’s where add_trickle_class_attr comes in. Its first call will snag the value from the SuperClass, but then it will have its own attribute that’s separate.

Again, watch:

 package SuperClass;


 package SubClass;
 @ISA = qw(SuperClass);

 print SubClass->foo();                 #prints bar
 print SuperClass->foo();               #prints bar

 print SuperClass->foo(baz);  #prints baz
 print SubClass->foo();                 #prints bar

 print SubClass->foo(dee);    #prints dee
 print SuperClass->foo();               #prints baz

This is useful if you have an attribute that should be unique to a class and all subclasses. These are equivalent:

 package SuperClass;

 package SubClass


 package SuperClass;

You’ll usually just use add_class_attr. Only use trickle_class_attr if you know you need to, since you rarely would. There is a *slight* bit of additional processing required for trickled accessors.

trickled class attributes are automatically initialized to any values in the conf file upon adding, if present.

error and errcode error rocks. All error reporting is set and relayed through error. It’s a standard accessor, and an *almost* standard mutator. The difference is that when used as a mutator, it returns undef (or an empty list) instead of the value mutated to.

If a method fails, it is expected to return undef (or an empty list) and set error.


 sub someMethod {
        my $self = shift;
        my $value = shift;

        if ($value > 10){
                return 1;               #success
        else {
                return $self->error("Values must be greater than 10");

 $object->someMethod(15) || die $object->error; #succeeds
 $object->someMethod(5)  || die $object->error; #dies with an error..."Values must be greater than 10"

Be warned if your method can return ’0’, this is a valid successful return and shouldn’t give an error. But most of the time, you’re fine with true is success, false is failure

As you can see in the example, we mutate the error attribute to the value passed, but it returns undef.

However, error messages can change and can be difficult to parse. So we also have an error code, accessed by errcode. This is expected to be consistent and machine parseable. It is mutated by the second argument to ->error


 sub someMethod {
        my $self = shift;
        my $value = shift;

        if ($value > 10){
                return 1;               #success
        else {
                return $self->error("Values must be greater than 10", "ERR77");

 $object->someMethod(15) || die $object->error;         #succeeds
 $object->someMethod(5)  || die $object->errcode;       #dies with an error code ... "ERR77"

If your code is looking for an error, read the errcode. if a human is looking at it, display the error. Easy as pie.

Both classes and objects have error methods.

 my $obj = Some::Class->new() || die Some::Class->error();
 $obj->foo() || die $obj->error();

Note that error is a special method, and not just a normal accessor or class attribute. As such:

 my $obj = Some::Class->new();
 print $obj->error();                   #prints undef
 print Some::Class->error();    #prints foo

i.e., you will <B>notB> get a class error message by calling ->error on an object.

There is also an optional third paramenter...not logged, which sounds horribly ugly, I know. But it is a bit of an after-market hack, so it’s to be expected. The third argument does what you’d think, it prevents the error message from being logged.

 $self->error("This is an error message", "code", "not logged");

Any true value may be passed for the 3rd argument, but something that makes it obvious what it’s doing is recommended, hence my use of ’not logged’. This is useful for bubbling up errors.

 $class->error($self->error, $self->errcode, not logged);

The reason is that the error was already logged when it was stored in $self. So you’d end up logging it twice in your error file, which is very confusing. So it’s recommended to use the three argument form for errors that are bubbling up, but not elsewhere.

As of 3.06, if an error is returned in a list context, an empty list will be returned instead of undef. undef is still returned in a scalar context.

errcode errcode is an accessor ONLY. You can only mutate the errcode via error, see above.

 print $obj->errcode;

Both objects and classes have errcode methods.

 my $obj = Some::Class->new() || die Some::Class->errcode();
 $obj->foo() || die $obj->errcode();

Where possible, the pod will note errors that a method is known to be able to return. Please note that this will <B>neverB> be an all inclusive list of all error codes that may possibly ever be returned by this method. Only error codes generated by a particular method will be listed.

errstring errstring is just a quick alias for:

 $bulk->error . ": " . $bulk->errcode;

Nothing more.

errvals similar to errstring, but returns the error and errcode in an array. This is great for bubbling up error messages.

 $attribute = $obj->foo() || return $self->error($obj->errvals);

read_conf_file read_conf_file will read in the conf files specified in the @conf_files array up at the top.

You can also pass in a list of conf files to read, in most to least significant order, same as the @conf_files array.

 my $conf = Mail::Bulkmail::Object->read_conf_file();
 my $conf = Mail::Bulkmail::Object->read_conf_file(/other/conf.file);

If you pass in a list of conf files, then the internal @conf_files array is bypassed.

$conf is a hashref of hashrefs. the main keys are the package names, the values are the hashes of the values for that object.


 #conf file
 define package Mail::Bulkmail

 use_envelope = 1
 Trusting @= duplicates

 define package Mail::Bulkmail::Server

 Smtp =
 Port = 25

 $conf = {
        Mail::Bulkmail => {
                use_envelope => 1,
                Trusting => [duplicates]
        Mail::Bulkmail::Server => {
                Smtp =>,
                Port => 25

read_conf_file is called at object initialization. Any defaults for your object are read in at this time. You’ll rarely need to read the conf file yourself, since at object creation it is read and parsed and the values passed on.

<B>Be sure to read up on the conf file structure, belowB>

The conf file is only re-read if it has been modified since the last time it was read.

this method is known to be able to return MBO002 - Invalid conf file

gen_handle returns a filehandle in a different package. Useful for when you need to open filehandles and pass ’em around.

 my $handle = Mail::Bulkmail->gen_handle();
 open ($handle, "/path/to/my/list");

 my $bulk = Mail::Bulkmail->new(
        LIST => $handle

You never need to use gen_handle if you don’t want to. It’s used extensively internally, though.

new Finally! The <B>constructorB>. It’s very easy, for a minimalist object, do this:

 my $obj = Class->new() || die Class->error();

Ta da! You have an object. Any attributes specified in the conf file will be loaded into your object. So if your conf file defines ’foo’ as ’bar’, then $obj->foo will now equal ’bar’.

If you’d like, you can also pass in method/value pairs to the constructor.

 my $obj = Class->new(
        attribute => 17,
        foo           => baz,
        method        => 88
 ) || die Class->error();

This is (roughly) the same as:

 my $obj = Class->new() || die Class->error();

 $obj->attribute(17) || die $obj->error();
 $obj->foo(baz) || die $obj->error();
 $obj->method(88) || die $obj->error();

Any accessors or methods you’d like may be passed to the constructor. Any unknown pairs will be silently ignored. If you pass a method/value pair to the constructor, it will override any equivalent method/value pair in the conf file.

Additionally, if you need to set up values in your object, this is the place to do it. Note that setting default values should probably be done in the conf file, but if you need to populate a data structure into a method, do it here.

 package SubClass;
 @ISA = qw(SuperClass);

 sub new {
        return shift->new(
                servers               => [],
                connections   => {},

This will cause your SubClass to use the normal constructor, but get default values of the empty data structures specified.

init The object initializer. Arguably more important than the constructor, but not something you need to worry about. The constructor calls it internally, and you really shouldn’t touch it or override it. But I wanted it here so you know what it does.

Simply, it iterates through the conf file and mutates any of your object attributes to the value specified in the conf file. It then iterates through the hash you passed to ->new() and does the same thing, overriding any conf values, if necessary.

init is smart enough to use all super class values defined in the conf file, in hierarchy order. So if your conf file contains:

 define package SuperClass

 foo = bar

And you’re creating a new SubClass object, then it will get the default of foo = ’bar’ as in the conf file, despite the fact that it was not defined for your own package. Naturally, the more significant definition is used.

 define package SuperClass

 foo = bar

 define package SubClass

 foo = baz

SuperClass objects will default foo to ’bar’, SubClass objects will default foo to ’baz’

this method is known to be able to return

 MBO003 - could not initialize value to conf value
 MBO004 - could not initialize value to constructor value
 MBO006 - odd number of elements in hash assignment

isa_path This is mainly used by the conf reader, but I wanted to make it publicly accessible. Given a class, it will return an arrayref containing all of the superclasses of that class, in inheritence order.

Note that once a path is looked up for a class, it is cached. So if you dynamically change @ISA, it won’t be reflected in the return of isa_path. Obviously, dynamically changing @ISA is frowned upon as a result.

getNextLine getNextLine is called on either a filehandleref, an arrayref, or a coderef


will return the next line off of FOO;


will shift the next line off of @foo and return it.


will call foo($obj) and return whatever the function returns.

Note that your bulkmail object is the first argument passed to your function. It’s not called as a method, but the object is still the first argument passed.

This is mainly used with attribues going through _file_accessor.

 package SomeClass;

 SomeClass->add_attr([FOO, _file_accessor], "<");
 my $obj = SomeClass->new(
        FOO => \&foo
 ) || die SomeClass->error();

 my $val = $obj->getNextLine($obj->FOO);

logToFile logToFile is the opposite of getNextLine, it writes out a value instead of reading it.

logToFile is called on either a filehandleref, an arrayref, or a coderef

 $obj->logToFile(\*FOO, "bar");

will append a new line to FOO, bar

 $obj->logToFile(\@foo, "bar");

will push the value bar onto the end of @foo

 $obj->logToFile(\&foo, "bar");

will call foo($obj, bar)

Note that your bulkmail object is the first argument passed to your function. It’s not called as a method, but the object is still the first argument passed.

This is mainly used with attribues going through _file_accessor.

 package SomeClass;

 SomeClass->add_attr([FOO, _file_accessor], ">>");
 my $obj = SomeClass->new(
        FOO => \&foo
 ) || die SomeClass->error();

 my $val = $obj->logToFile($obj->FOO, "valid address);

Internally, logToFile calls convert_to_scalar on the value it is called with.

This method is known to be able to return:

 MBO005 - cannot log to file

convert_to_scalar called by logToFile. used to convert the value passed to a scalar.

Mail::Bulkmail::Object’s convert_to_scalar method will only handle scalars, it will dereference scalarrefs, or return scalar values. This method will also strip out any carriage returns or newlines within the scalar before returning it. If passed by reference, your original variable will not be modified.

This is useful to subclass if you ever want to log values other than simple scalars

ERRFILE This is an optional log file to keep track of any errors that occur.

ERRFILE may be either a coderef, globref, arrayref, or string literal.

If a string literal, then Mail::Bulkmail::Object will attempt to open that file (in append mode) as your log:


If a globref, it is assumed to be an open filehandle in append mode:

 open (E, ">>/path/to/my/error.file");

if a coderef, it is assumed to be a function to call with the address as an argument:

 sub E { print "ERROR : ", shift, "\n"};        #or whatever your code is

if an arrayref, then bad addresses will be pushed on to the end of it


Use whichever item is most convenient, and Mail::Bulkmail::Object will take it from there.

It is recommended you turn on ERRFILE in a debugging envrionment, and leave it off in production. You probably shouldn’t be getting errors in a production environment, but there may be internal errors that you’re not even aware of, so you’ll end up filling up that file. And there’s the slight additional overhead.

Keep it on in production if you know what you’re doing, off otherwise.

CONF FILE specification

Your conf files are very important. You did specify them up in the @conf_files list above, right? Of course you did.

But now you need to know how they look. They’re pretty easy.

Each line of the conf file is a name = value pair.

 ERRFILE = /path/to/err.file

Do not put the value in quotes, or they will be assigned.

 ERRFILE = /path/to/err.file            #ERRFILE is /path/to/err.file
 ERRFILE = "/path/to/err.file"          #ERRFILE is "/path/to/err.file"

the conf file is analyzed by the object initializer, and then each value is passed to the appropriate object upon object creation. So, in this case your ERRFILE class_attribute would be set to ERRFILE leading and trailing whitespace is stripped.

 so these are all the same:
 ERRFILE = /path/to/err.file
    ERRFILE        =     /path/to/err.file
            ERRFILE =        /path/to/err.file
                                                                                        ^^^^^extra spaces

Your conf file is read by read_conf_file. As you saw in the docs for read_conf_file, it creates a hashref. The top hashref has keys of package names, and the conf->{package} hashref is the name value pairs. To do that, you’ll need to define which package you’re looking at.

 define package SomeClass

 define package OtherClass

 ERRFILE = /path/to/err.file

So ERRFILE is now defined for OtherClass, but not for SomeClass (unless of course, OtherClass is a sub-class of SomeClass)

If you do not define a package, then the default package is assumed.

Multiple entries in a conf file take the last one.

 define package SomeClass

 ERRFILE = /path/to/err.file
 ERRFILE = /path/to/err.other.file

so SomeClass->ERRFILE is /path/to/err.other.file There is no way to programmatically access /path/to/err.file, the value was destroyed, even though it is still in the conf file.

There is one magic value token...undef

 ERRFILE = undef

This will set ERRFILE to the perl value ’undef’, as opposed to the literal string undef

Sometimes, you will want to give a conf entry multiple values. Then, use the @= syntax.

 define package SomeClass

 foo = 7
 bar @= 8
 bar @= 9

SomeClass->foo will be 7, SomeClass->bar will be [8, 9]

There is no way to assign a value more complex than a scalar or an arrayref.

Comments are lines that begin with a #

 #enter the SomeClass package
 define package SomeClass

 #connections stores the maximum number of connections we want
 connections = 7

If you want to get *really* fancy, you can restrict values to the user that is running the script. Use the :ID syntax for that.

 define package SomeClass

 #everyone else gets this value
 foo = 11

 #user 87 gets this value
 87:foo = 9

 #user 93 gets this value
 93:foo = 10

Note that a default value must be listed FIRST, or it will override any user specific values.


 #this is in the default package
 ERRFILE = /path/to/err.file

 define package Mail::Bulkmail::Server
 #set our Smtp Server
 Smtp   = your.smtp.cpm

 #set our Port
 Port   = 25

 define package JIM::SubClass

 #store the IDs of the server objects we want to use by default

 servers @= 7
 servers @= 19
 servers @= 34


In fact, we’ll even get fancy, and specify an ABNF grammar for the conf file.

        CONFFILE = *(LINE "\n")                                 ; a conf file consists of 0 or more lines

        LINE = (
                        DEFINE                  ; definition line
                        / COMMENT               ; comment line
                        / EQUATION              ; equation line
                        / *(WSP)                ; blank line
                ) "\n"                          ; followed by a newline character

        DEFINE = %b100 %b101 %b102 %b105 %b110 %b101 %b32 %b112 %b97 %b99 %b107 %b97 %b103 %b101 TEXT
                ; the literal string "define package" in lower case, followed by TEXT

        COMMENT = *(WSP) "#" TEXT



        USER = 1*(DIGIT)

        EQUATION_SYMBOL = "=" / "@="

        VALUE = *(TEXT)



        VISIBLE = %d33-%d126    ; visible ascii characters


Mail::Bulkmail, Mail::Bulkmail::Server


Copyright and (c) 1999, 2000, 2001, 2002, 2003 James A Thomason III ( All rights reserved. Mail::Bulkmail::Object is distributed under the terms of the Perl Artistic License.


So you don’t have to scroll all the way back to the top, I’m Jim Thomason ( and feedback is appreciated. Bug reports/suggestions/questions/etc. Hell, drop me a line to let me know that you’re using the module and that it’s made your life easier. :-)


Hey! <B>The above document had some coding errors, which are explained below:B>
Around line 1478: =cut found outside a pod block. Skipping to next block.
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