Revision history for Perl extension Class::Contract.

Planned for next release:

• Long overdue documentation update
• Rewrite tests using MSCHWERN's new Test::Harness
• Flattening and shortening

1.14 Mon Jun 18 16:28:02 2001

• <C>croak</C> and <C>carp</C> are wrapped to facilitate reporting correct file and line numbers within <C>impl</C>. Previously it was hard to get useful file/line information when throwing an exception within implementations.
• <C>private</C> Forgetting to declare an inherited private method private will cause croak. If for example you are adding pre/post-conditions or defining a new implementation for a derived method, you must declare it 'private', or an exception will be raised.
• <C>old</C> is now off by default. I have noticed, and others have complained that it caused too much overhead. To toggle on/off per package: use Class::Contract 'old'; no Class::Contract 'old';

1.13 Mon May 07 10:47:21 2001

• Fixed deep copy of scalar references. Was breaking <C>old</C> and <C>clone</C>.

1.12 Tue Mar 13 08:53:06 2001

• Removed cruft from t/method.t test which was causing a false indication of test failures on some platforms. No code changes to Class::Contract itself.

1.11 Mon Mar 05 10:31:54 2001

• Added support for clone method which may be used as you might imagine. To clone an object. Like ctor you may use clon to define initialization pre, impl, post, and invar clauses to execute when cloning an object.
• Fixed problem working with objects which weren't created with Class::Contract. Problems arose when an object wasn't a scalar reference.
• Fixed typo in _dcopy which broke deep copying of scalar references

1.10 Sun Feb 09 12:15:31 2001

• Added missing <C>old</C>. It was documented but not implemented
• &self is now only way to access object/class reference. Use self(self->next) instead of $_[0] = $_[0]->next.
• refactored all condition checking to use <C>generic_check</C> function
• revisted inheritence and genericcheck. Think I've finally got weakening pre-conditional checks working correctly. There is a good test covering this in t/method.t

1.04 Wed Jan 31 15:45:42 2001

• Begun the process of writing extensive tests. Finding and fixing many bugs.
• Calling a class accessor or method with an object reference will now auto-magically change &self into a class name reference. This was documented but not implemented. The converse, calling an object accessor or method with a class reference causes an assertion
• Added keyword 'private'. Methods declared private can only be invoked by the class or its descendants.
• Added optional exportation of shortcuts: scalar_attrs, array_attrs, hash_attrs, methods. Allows defining clauses like: abstract methods qw( foo bar baz );
• Fixed inheritence of pre-condition and implementation sub-clauses. Sub-clauses weren't always inherited when the derived class failed to define one.
• Fixed pre-condition checks. Satisfying self or any ancestor wasn't working correctly when either the ancestor or the derived class did not define any preconditions.
• &inherits now croaks on circular references in inheritence
• Rewrote _location so we can now use eval within the contract statement to generate attribs, methods, etc.
• Post conditions and invariants can no longer modify by reference a method's @_. Now conditional checks receive a @{[@_]} shallow copy.
• Fixed flyweight objects returned by constructor to avoid a dangling reference which was preventing garbage collection.

  The flyweight object is a blessed reference to $key which is itself a reference to an undefined lexical scalar. $key is also used as the hash key to the lexical %Class::Contract::data which stores a given object's data. Previously constructors returned $key. Consequently, when an object went out of scope in your script, %data continued to reference $key. Now, when the flyweight, which is not internally referenced by Class::Contract, goes out of scope its destructor clears $data{$key}, and Perl's garbage collection takes place. For a coherent explanation of such issues read section 13.13 of the Perl Cookbook, 1st Edition.

• Fixed multiple inheritence to appropriately handle cases where a descendant might inherit the same base class through 2 or more intermediary classes. I.e. diamond patterns in inheritence tree. This affects inheritence of invars, attributes, methods, constructors, and destructors. Previously, it was possible to have a base class' initialization code called multiple times by a descendant's constructor. Once for each ancestor with the common base class.
• Fixed multiple inheritence with regard to constructor initialization to be left-most depth-first, instead of right-most depth-first. Destructors are the symetrical opposite right-most derived-first.

1.03 Wed Dec 27 14:06:11 2000

• Reformatted source to new maintainer's tastes. 2 space indent and tabs, removal of barewords, foreach instead of for, etc. Otherwise no changes to the underlying code.

1.02 Fri Dec 21 10:22:48 2000

• One line change to C<generic_precheck> to fix improper skipping pre-conditional checks in some cases (thanks Jeff)

1.01 Fri Dec 9 09:52:02 2000

• Change to generic constructor to work around magical limitations of overload.pm. Should now play nicer with overload.pm
• Reversed ordering of Changes (this document)
• Updated documentation to reflect probationary new maintainer C. Garrett Goebel, GGOEBEL, <ggoebel@cpan.org>

1.00 Sun Aug 6 07:11:35 2000

• Changed semantics of preconditions. Now only inherited if not defined in same class (this conforms with the notion of derived classes being allowed to weaken, but not strengthen preconditions).
• Added postconditions on SCALAR, ARRAY, and HASH attributes
• Added &value for attr conditions
• Removed &result -- now uses &value instead
• Added warning when explicit preconditions in derived class override inherited preconditions from base class.
• Added default ctor ('new') if none specified.
• Modified flyweight implementation (more robust, secure, and efficient)
• Modified ctors to refuse to instantiate classes with 1+ abstract methods.
• Added class constructors and destructors
• Changed production code mechanism (now a separate, accelerated class: Class::Contract::Production)

0.05 Wed Nov 24 14:11:22 1999

• First beta version

0.01 Fri Jul 23 14:35:54 1999

• original version; created by h2xs 1.18 (very much alpha)

Future Plans and Ponderings:

• Someday rewrite to use Attribute::Handlers
• Damian's Legacy
  • Class Flattening and shortening
  • Easier mechanisms for porting code to use CC. Like allowing pre-declared subroutines to be assimilated into contract
• Update documentation...
  • better examples of using objects in contracts
  • functions: scalar_attrs, array_attrs, hash_attrs, private, clon
• Constructor
  • Allow user-defined default values for attributes
  • Ponder whether or not it would be a good idea to provide a better default mechanism for setting object attribute values during construction. Particularly attributes which are themselves objects.
• <C>old</C>
  • Reexamine implementation of <C>old</C> with attention to destructors and cleanup of the temporarily allocated package namespace better. Worry about magic and stash de-allocation.
• <C>post</C>: Add support for post-conditions on objects? How? Scalars, arrays, and hashes are actually tied objects and do this on destruction. Perhaps support post conditions on objects created via Class::Contract by return a blessed reference to the same $key used to lookup object data in the lexical Class::Contract %data. And provide an object attribute for post-conditions that gets called by doppleganger on destruction?
• Tests
  • Restructure and expand
  • Check out new version of Test::Harness and see if I can drop the Magic.pm hack used for testing.
• Add support for <C>friend</C> classes?