Craig Schaffert, Topher Cooper and Carrie Wilpolt. Trellis: Object-Based Environment Language Reference Manual. Technical Report 372, Digital Equipment Corp./Easter Research Lab., 1985.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....is described in the trait BicycleTrait found in Figure 4.9. Let be the smallest reflexive relation on the types of Vehicles such that Bicycle Vehicle. Let C be a Vehicles algebra. Then the family of relations R from C to itself constructed from the specification as Some researchers (e.g. [SCW85, Page 42] [Sym84, Page 450] call a type or class that cannot be instantiated abstract, but this leads to confusion with the term abstract data type. In Eiffel, operations that are not implemented are said to be deferred [Mey88] 36 Vehicle virtual type instance ops [wheels, passengers] based on ....

Craig Schaffert, Topher Cooper, and Carrie Wilpolt. Trellis Object-Based Environment: Language Reference Manual. Technical Report DEC-TR-372, Eastern Research Lab, Digital Equipment Corp., Hudson, Mass., November 1985.

.... investigation of persistence and its application to the integration of database systems and programming languages [ABC 83, AM95] A number of persistent systems have been developed including PS algol [PS88] Napier88 [MBC 89] Galileo [ACO85] TI Persistent Memory System [Tha86] and Trellis Owl [SCW85]. Most of the object oriented database products now commercially available provide some form of persistent language interface, and most recently Sun Microsystems and others are involved in a number of experiments in adding the concepts of persistence to Java [AJDS97, GN98] Whilst many of the ....

Schaffert, C., Cooper, T. & Wilpot, C. "Trellis Object-Based Environment Language Reference Manual". DEC Technical Report 372 (1985).

....most objects are not shared. Hence, the programmer is in charge to coordinate accesses to shared objects. For this purpose concurrent Trellis offers 1st class lock objects. fault tolerance. Availability: The system is implemented on a VAX 11 785 and MicroVAX running VMS. References: 166] 187] [188] 2.97 Ubik Developer: IBM Cambridge Scientific Center. Description: Describes a generalization of the Actor model. oo. memory model. parallelism. Actor language. Asynchronous message passing only. Early become for postprocessing. Return values, if any, have to be passed back by a separate ....

Craig Schaffert, Topher Cooper, and Carrie Wilpolt. Trellis -- object-based environment: Language reference manual. Technical Report DEC-TR-372, Eastern Research Lab, DEC, Hudson, Massachusetts, November 1985.

....Gregory R. Andrews Gamma greg cs.arizona.edu Tool [63] Phi Phi Delta Delta H H A A Phi Phi Delta Delta H H A A hijklm y t i v i t c a y r a d n u o b http: www.inf.puc rio.br sergio tool Sergio E. R. de Carvalho Gamma sergio inf.puc rio.br Trellis Owl [180, 206, 207] Phi Phi Delta Delta H H A A Phi Phi Delta Delta H H A A m y t i v i t c a y r a d n u o b Ubik [83] Phi Phi Delta Delta H H A A Phi Phi Delta Delta H H A A y t i v i t c a y r a d n u o b Peter De Jong Gamma pdjong vnet.ibm.com ....

Craig Schaffert, Topher Cooper, and Carrie Wilpolt. Trellis -- object-based environment: Language reference manual. Technical Report DEC-TR-372, Eastern Research Lab, DEC, Hudson, Massachusetts, November 1985.

....polymorphism for data structures like lists, queues, and trees. For example, a procedure that reverses a list object can safely be applied both to lists of integers and to lists of reals. All Modula 3 objects are references (unlike in C [12] Modula 3 allows only single inheritance (unlike Owl [11]) Generally the lowest levels of a system cannot be programmed with complete safety. Neither the compiler nor the runtime system can check the validity of a bus address for a peripheral device, nor can they limit the ensuing havoc if it is invalid. This presents the language designer with a ....

Craig Schaffert, Topher Cooper, and Carrie Wilpolt. Trellis Object-Based Environment Language Reference Manual. DEC Eastern Research Lab, DEC-TR-372, 1985.

....of the objects of the two types: the objects of the subtype ought to behave the same as those of the supertype as far as anyone or any program using supertype objects can tell. For example, in strongly typed object oriented languages such as Simula 67[9] C [35] Modula 3[32] and Trellis Owl[33], subtypes are used to broaden the assignment statement. An assignment x: T : E Supported in part by the Advanced Research Projects Agency of the Department of Defense, monitored by the Office of Naval Research under contract N00014 91 J 4136 and in part by the National Science Foundation under ....

....correctly when the actual type of x s object is T, it will also work correctly if the actual type of the object denoted by x is a subtype of T. Clearly subtypes must provide the expected methods with compatible signatures. This consideration has led to the formulation of the contra covariance rules[3, 33, 5]. However, these rules are not strong enough to ensure that the program containing the above assignment will work correctly for any subtype of T, since all they do is ensure that no type errors will occur. It is well known that type checking, while very useful, captures only a small part of what ....

[Article contains additional citation context not shown here]

Craig Schaffert, Topher Cooper, and Carrie Wilpolt. Trellis: Object-based environment language reference manual. Technical Report 372, Digital Equipment Corp./Easter Research Lab., 1985.

.... btn : binaryTreeNode[ keyType, entityType, compare ] btn root; public: binaryTree( entityType search( keyType ) void insert( keyType, entityType ) ############################################################################################## Figure 7: A Generic Binary Tree Class [Scha85], and Eiffel [Meye86] Another language that supports generics of this sort is the most recent version of C , i.e. C v.3.0 [Elli90] A generic class or function in C v.3.0 is called a template. Unlike an E generator class, a template class cannot specify constraints on the instantiating ....

....latter case, any class instantiated from T1 becomes a subclass of one instantiated (automatically) from T2 with the same parameters. For example, in C v.3.0, we can define Set T to inherit from Collection T so that for a specific type T , Set T is a subtype of Collection T . Trellis Owl [Scha85] and Eiffel [Meye88] also support this kind of definition. Similar to C , E allows a class instantiated from a class generator to serve as a base class for further subtyping. E also allows a generator class to inherit from other types or generics, thus supporting the incremental definition of ....

Schaffert, C., Cooper, T., and Wilpolt, C., "Trellis Object-Based Environment: Language Reference Manual," DEC-TR-372, November, 1985.

....itself or within its run time support system. Since then many persistent languages have been developed including Abstract Data Store [Pow85] Amber [Car86] Fibonacci [ABG 93] Flex [Cur85] Galileo [ACO85] Napier88 [MBC 94] PS algol [PS88] TI Persistent Memory System [Tha86] Trellis Owl [SCW85] and Tycoon [MS92] Here we selectively draw on the PS algol Napier88 experience which developed a strongly typed orthogonally persistent programming environment. We show how, by providing a basic number of facilities at the system support level, the programming techniques of strongly typed ....

Schaffert, C., Cooper, T. & Wilpot, C. "Trellis Object-Based Environment Language Reference Manual". DEC Systems Research Center (1985).

....by a graph. This graph is highly dependent on the form(s) of inheritance that a system supports. For example, Smalltalk 80 [GR85] enforces (1) and (2) but allows inheriting types (subtypes) to change the arguments and semantics of inherited functions. The public and private declarations of Owl [SCW85] and C [Str86] allow (1) and (2) to be chosen for each data component and function on an individual basis. A system can have multiple inheritance graphs. LaLonde [LTP86] describes a Smalltalk 80 variant which has one inheritance graph for implementations and a second for behavioral ....

C. Schaffert, T. Cooper, and C. Wilport. Trellis Object-Based Environment Language Reference Manual. Technical Report DEC-TR-372, Digital Equipment Corporation, 1985.

....on the notion of type conformance. Conformance is a relation between types which determines whether objects of one type can be used in lieu of objects of another as discussed in the context of Definition 5. A number of object based or object oriented languages such as Emerald [BLA87] Trellis Owl [SCH85], Eiffel [MEY88] and object models such as TEDM [MZO89] and FROOM [MaB90] have adopted the notion of conformance to determine whether an object is of the specified type by comparing its interfaces with the interface specified by the type in question. Observation 1 The signatures, i.e. type ....

Schaffert C, et al. (1985) Trellis object based environment: language reference manual. DEC Techn. report DEC-TR-373

.... et al. 1983] A number of persistent systems have been developed including: PS algol [Atkinson, et al. 1983, PS algol, 1988] Abstract Data Store [Powell, 1985] Flex [Currie, 1985, Stanley, 1986, Stanley Drummond, 1988] Galileo [Albano et al. 1985] Amber [Cardelli, 1986] Trellis Owl [Schaffert et al. 1985], TI Persistent Memory System [Thatte, 1986] Tycoon [Matthes Schmidt, 1992] Napier88 [Morrison et al. 1994] and Fibonacci [Albano et al. 1995] The underlying goal in this work is to achieve engineering that is of sufficiently high quality to ensure that the orthogonal persistence ....

Schaffert, C., Cooper, T. & Wilpot, C., 1985. Trellis Object-Based Environment Language Reference Manual . DEC Systems Research Center.

....is restrained or the association must disappear. If the association disappears, value variables become meaningless, whilst references and pointers can perfectly map to the notion of object references found in almost all other object oriented languages (e.g. Eiffel[12] Objective C[4] Trellis Owl [15]) 2.2 Visibility of members In C visibility of member access is specified on a class basis and range from private (only for this class member functions) protected (this and derived classes member functions) and public (any function can access that member) Orthogonally, C also makes ....

Craig Schaffert, Topher Cooper, and Carrie Wilpolt. Trellis Object-Based Environment Language Reference Manual. Technical Report DECTR -372, DEC, November 1985.

.... in the integration of database systems and programming languages [Atk78, ABC 83] As a result a number of persistent systems have been developed including Pascal R, PS algol [PS88] Napier88 [MBC 89] DBPL [MS89] Galileo [ACO85] TI Persistent Memory System [Tha86] Amber [Car85] Trellis Owl [SCW85] and Tycoon [MS92] The persistence abstraction has been recognised as the appropriate underlying technology for long lived, concurrently accessed and potentially large bodies of data and programs. Typical examples of such systems are CAD CAM systems, office automation, CASE tools and software ....

Schaffert, C., Cooper, T. & Wilpot, C. "Trellis Object-Based Environment Language Reference Manual". DEC Systems Research Center Technical Report 372 (1985).

....conform. A method signature M is conformant to a method signature L if their names are identical; their number of arguments are the same; the types of their arguments are compatible; and their return values are compatible. Our rules for type compatibility are the same as those used by Trellis Owl [17]. The mechanisms used by the ORM for the addition of new role classes in the lattice present many similarities with the structural consistency as supported by schema evolution in systems like Orion [2] and O 2 [18] whereas signature compatibility as used here can be found in systems like Emerald, ....

Schaffert et. al, "Trellis Object-Based Environment: Language Reference Manual ", DEC Techn. report DEC-TR-373, Nov. 1985.

....Linearization has two drawbacks: it masks ambiguities between otherwise unordered ancestors, and it fails with inheritance graphs that it deems inconsistent. The opposite approach to resolving ambiguities among an object s parents is to leave it up to the programmer. Languages like Trellis Owl [17, 18], Eiffel [14, 15] C version 2.0 [23, 24] and CommonObjects [20, 21] treat an object s parents as equals without a relative ordering and treat ambiguities as programming errors that need to be explicitly resolved by the programmer. 3 We call this approach unordered inheritance. It works best ....

Schaffert, C., Cooper, T., and Wilpolt, C. Trellis Object-Based Environment: Language Reference Manual, Version 1.1. DEC-TR-372, Digital Equipment Corp., Hudson, MA (1985).

....methods needed for the vertices data slot or modifications to the invoking methods. This convenience is afforded by SELF s uniform use of messages to access both state and behavior, and could be adopted by other classless and class based languages to achieve similar flexibility. Trellis Owl [12, 13], a class based language, also accesses instance variables using messages and is able to change the representation of a subclass by overriding the instance variables inherited from its superclasses with methods defined in the subclass. An implementation of a data type in a classless language can ....

Schaffert, C., Cooper, T., and Wilpolt, C. Trellis Object-Based Environment: Language Reference Manual, Version 1.1. DEC-TR-372, Digital Equipment Corp., Hudson, MA (1985).

No context found.

Craig Schaffert, Topher Cooper and Carrie Wilpolt. Trellis: Object-Based Environment Language Reference Manual. Technical Report 372, Digital Equipment Corp./Easter Research Lab., 1985.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC