NAME
Method::Cascade - Use method chaining with any API
SYNOPSIS
use Method::Cascade;
use IO::Socket::INET;
cascade(IO::Socket::INET->new('google.com:http'))
->timeout(5)
->setsockopt(SOL_SOCKET, SO_KEEPALIVE, pack("l", 1))
->print("GET / HTTP/1.0\r\n\r\n")
->recv(my $response, 4096);
print $response;
BACKGROUND
Method chaining is a very intuitive and convenient way to make
sequential method calls on the same object.
Unfortunately, not all APIs support method chaining. In order for an API
to be chainable, every method must return $self. However often there are
good reasons for an API to not return $self. For instance, it can be
useful for setter methods to return the previous values.
Method cascading is a feature borrowed from Smalltalk. Its advantage is
that any API can be used in a chained fashion, even if the designers
didn't plan or intend for it to be chainable. You, the user of the API,
can choose if you care about the return values and, if not, go ahead and
cascade method calls.
DESCRIPTION
This module exports one function: "cascade". You should pass it the
object that you would like to chain/cascade method calls on. It will
return a wrapper object that forwards all method calls to the object you
passed in. After forwarding, it returns the same wrapper object.
Because return values are ignored (the methods are in fact called in
void context), method cascading is most useful when used with APIs that
throw exceptions instead of returning error values. For instance, with
DBI, as long as "RaiseError" is true and "AutoCommit" is false you can
safely do the following:
cascade($dbh)->do("INSERT INTO admins (name) VALUES (?)", undef, $user)
->do("DELETE FROM users WHERE name=?", undef, $user)
->commit;
OTHER LANGUAGES
As mentioned, method cascading was first invented in Smalltalk.
Dart is a web-language that has also added
this feature. In Dart, the ".." operator is a method cascading operator
that returns the object the method was invoked on instead of the method
call result. Here is a Dart example:
myTokenTable
..add("aToken")
..add("anotherToken")
// and on and on
..add("theUmpteenthToken");
SEE ALSO
The Method::Cascade github repo
Method Cascades in Dart
Wikipedia entry on Method Cascading
IO::All - I/O library that makes heavy use of chaining
AUTHOR
Doug Hoyte, ""
Thanks to Richard Farr for helping me come up with this idea (during a
conversation about C++ smart pointers).
COPYRIGHT & LICENSE
Copyright 2014 Doug Hoyte.
This module is licensed under the same terms as perl itself.