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VCS::CMSynergy::Object
convenience wrapper to treat objectnames as an object

VCS::CMSynergy::Object - convenience wrapper to treat objectnames as an object


NAME

VCS::CMSynergy::Object - convenience wrapper to treat objectnames as an object


SYNOPSIS


  use VCS::CMSynergy;

  $ccm = VCS::CMSynergy->new(%attr);

  ...

  $obj = $ccm->object($name, $version, $cvtype, $instance);

  $obj = $ccm->object($objectname);

  print ref $obj;                       # "VCS::CMSynergy::Object"

  # objectname and its constituents

  print "...and the object is $obj";

  print "name       = ", $obj->name;

  print "version    = ", $obj->version;

  print "cvtype     = ", $obj->cvtype;

  print "instance   = ", $obj->instance;

  print "objectname = ", $obj->objectname;

  # attribute methods, optionally caching with 

  #   use VCS::CMSynergy ':cached_attributes'

  print $obj->get_attribute('comment');

  $obj->set_attribute(comment => "blurfl");

  $obj->create_attribute("foo", string => "some text");

  $obj->delete_attribute("foo");

  $hashref = $obj->list_attributes;     # always caches result

  # property methods

  print $obj->property("bar");

  print $obj->displayname;              # always caches result

  ## tiehash interface

  use VCS::CMSynergy ':tied_objects';

  $ccm = VCS::CMSynergy->new(%attr);

  ...

  print $obj->{comment};        

  $obj->{comment} = "blurfl";   

  # same as:

  #   print $ccm->get_attribute(comment => $obj);

  #   $ccm->set_attribute(comment => $obj, "blurfl");

This synopsis only lists the major methods.


DESCRIPTION

A VCS::CMSynergy::Object is mostly a glorified wrapper for a CM Synergy's objectname (sometimes called object reference form in CM Synergy documentation). Because of its overloaded string conversion method (see below), it can be used with VCS::CMSynergy methods wherever an objectname would be appropriate, esp. where the documentation specifies a file_spec.

When :cached_attributes in the VCS::CMSynergy::Object manpage is in effect, a VCS::CMSynergy::Object keeps a ``demand loaded'' cache of attribute names and values.

There is also a TIEHASH INTERFACE for manipulating an object's attributes using the hash notation.


BASIC METHODS

new


  # let $ccm be a VCS::CMSynergy

  $obj = VCS::CMSynergy::Object->new(

    $ccm, $name, $version, $cvtype, $instance);

  # more conveniently

  $obj = $ccm->object($name, $version, $cvtype, $instance);

  $obj2 = $ccm->object("name-version:cvtype:instance");

Create a VCS::CMSynergy::Object from a CM Synergy session and either an objectname (sometimes called object reference form in CM Synergy documentation) in ``name-version:cvtype:instance'' format or the four parts specified separately.

Usually you would not call this method directly, but rather via the wrapper object in the VCS::CMSynergy manpage.

Note that no check is made whether the corresponding object really exists in the CM synergy database, use exists for that.

If you are useing :cached_attributes in the VCS::CMSynergy manpage, invoking new several times with the same objectname always returns the same VCS::CMSynergy::Object. This also holds for any method that returns VCS::CMSynergy::Objects (by calling new implicitly), e.g. object in the VCS::CMSynergy manpage or query_object in the VCS::CMSynergy manpage.

objectname


  print $obj->objectname;

Returns the object's complete name in object reference form, i.e. "name-version:cvtype:instance" where "-" is meant as a placeholder for the actual delimiter of the CM synergy database.

name, version, cvtype, instance


  print $obj->name;

  print $obj->version;

  print $obj->cvtype;

  print $obj->instance;

Returns the object's name, version, type, or instance, resp.

string conversion

VCS::CMSynergy::Object overloads string conversion with objectname, i.e. the following expressions evaluate to the same string:


  "$obj"  

  $obj->objectname

This makes it possible to use a VCS::CMSynergy::Object throughout VCS::CMSynergy wherever an objectname would have been appropriate.

is_project, is_dir


  if ($obj->is_project) { ... }

These are convenience functions that test whether the object's type is "project" or "dir", resp.

ccm


  $obj->ccm->query_hashref(...);

ccm returns the session (a VCS::CMSynergy) that is associated with the object.


ATTRIBUTE METHODS

get_attribute, set_attribute


  print $obj->get_attribute($attribute_name);

  $obj->set_attribute($attribute_name) = "blurfl";

These are convenience wrappers for get_attribute in the VCS::CMSynergy manpage and set_attribute in the VCS::CMSynergy manpage, resp., i.e.


  print $obj->get_attribute("comment");

is syntactic sugar for


  print $ccm->get_attribute(comment => $obj);

If you are useing :cached_attributes in the VCS::CMSynergy manpage, these methods maintain a cache of attribute names and values in the object. Note that this cache is only consulted if you use VCS::CMSynergy::Object methods (including the TIEHASH INTERFACE) and will get inconsistent if you mix VCS::CMSynergy::Object and VCS::CMSynergy calls on the same object.

create_attribute, delete_attribute


  $obj->create_attribute($attribute_name, $attribute_type);

  $obj->delete_attribute($attribute_name);

Convenience wrappers for create_attribute in the VCS::CMSynergy manpage and delete_attribute in the VCS::CMSynergy manpage, resp. Also update the cache when :cached_attributes in the VCS::CMSynergy manpage is in effect.

copy_attribute


  $obj->copy_attribute($attribute_name, @to_file_specs);

Convenience wrapper for copy_attribute in the VCS::CMSynergy manpage. Also invalidate the cache entries for $attribute_name for all VCS::CMSynergy::Objects in @to_file_specs when :cached_attributes in the VCS::CMSynergy manpage is in effect.

Note: The optional $flags parameter of copy_attribute in the VCS::CMSynergy manpage is not supported, because it would mean traversing the target projects to update or invalidate attribute caches.

list_attributes


  $hashref = $obj->list_attributes;

Convenience wrapper for list_attributes in the VCS::CMSynergy manpage.

Note that the returned hash is always cached in the object (and updated for successful create_attribute and delete_attribute calls).

exists


  print "$obj doesn't exist" unless $obj->exists;

Tests whether the VCS::CMSynergy::Object corresponds to an object in the CM Synergy database (without causing an exception if it doesn't).


PROPERTY METHODS

property


  $value = $obj->property($keyword);

  $hash = $obj->property(\@keywords);

Convenience wrapper for property in the VCS::CMSynergy manpage, equivalent to


  $value = $ccm->property($keyword, $obj);

  $hash = $ccm->property(\@keywords, $obj);

displayname, cvid


  print $obj->displayname;

  print $obj->cvid;

Short hand for $obj->property("displayname") or $obj->property("cvid"), resp. However, these two methods caches their return value in the VCS::CMSynergy::Object (because it is immutable).


is_RELATION_of, has_RELATION


  $tasks = $obj->has_associated_cv;

These are convenience methods to quickly enumerate all objects that are somehow related to the invoking object:


  $obj->is_RELATION_of

  $obj->has_RELATION

are exactly the same as


  $obj->ccm->query_object("is_RELATION_of('$obj')")

  $obj->ccm->query_object("has_RELATION('$obj')")

If you supply extra arguments then these are passed down to query_object in the VCS::CMSynergy manpage as additional keywords.

See the CM Synergy documentation for the built-in relations. Note that it's not considered an error to use a non-existing relation, the methods will simply return (a reference to) an empty list. This is consistent with the behaviour of ccm query in this case.


TIEHASH INTERFACE


  use VCS::CMSynergy ':tied_objects';

  ...

  print $obj->{comment};        

  $obj->{comment} = "blurfl";

When useing :tied_objects in the VCS::CMSynergy manpage, you can use a VCS::CMSynergy::Object in the same way you would use a hash reference. The available keys are the underlying CM Synergy object's attributes.

Note that contrary to the behaviour of real hashes, keys don't spring into existence ``on demand''. Getting or setting the value of an attribute that does not exist for the underlying CM Synergy object will return undef or throw an excpetion (depending on your sessions's setting of RaiseError in the VCS::CMSynergy manpage). However, testing for the existence of an attribute with exists works as expected.

NOTE: When using :tied_objects in the VCS::CMSynergy manpage, it is strongly recommended to have Scalar::Util installed. See Why is Scalar::Util recommended? for an explanation.

FETCH, STORE


  $value = $obj->{attribute_name};

  $obj->{attribute_name} = $value;

These are wrappers for get_attribute and set_attribute, resp. The operate on the same cache as these when using :cached_attributes in the VCS::CMSynergy manpage

EXISTS

Checks the return value from list_attributes for the existence of the key (attribute) given.

FIRSTKEY, NEXTKEY


  foreach (@{ $obj->keys })  { ... }

  foreach (@{ $obj->values })  { ... }

  while (my ($attr, $val) = each %$obj)  { ... }

These methods use list_attributes to obtain a list of attributes and then iterate over this list. Hence keys, values, and each all work as expected.

Warning: Enumerating the keys (i.e. attribute names) of a tied VCS::CMSynergy::Object is cheap (at most one call to ccm attribute -la), but enumerating the values may result in lots of calls to ccm attribute -show. Tools like the Data::Dumper manpage or similar will implicitly enumerate all keys and values when invoked on a tied object. This is especially annoying when using the graphical Perl debugger the Devel::ptkdb manpage and mousing over a variable holding a tied object, because the debugger uses the Data::Dumper manpage to construct a printable representation of the object.

Why is Scalar::Util recommended?

Every VCS::CMSynergy::Object keeps a reference to the session (a VCS::CMSynergy) where it was created in. It needs this ``back pointer'' so it can implement methods that invoke CM Synergy operations, e.g. get_attribute. These references can prevent the timely garbage collection of a session (esp. ccm stop called from DESTROY in the VCS::CMSynergy manpage) if a VCS::CMSynergy::Object has a longer lifetime than its session. (The latter is actually a programmer error, but there's no way to enforce the correct lifetime rule.) To work around this we need to make the session reference not count w.r.t. to garbage collection. We use weaken in the Scalar::Util manpage for that. If the VCS::CMSynergy object goes away before the VCS::CMSynergy::Object gets destroyed, its session reference will become undef. Any method called on the VCS::CMSynergy::Object after this point that tries to invoke a session method will result in a (rightly deserved) error (Can't call method "..." on an undefined value).


SEE ALSO

the VCS::CMSynergy manpage

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