Testing Basic Interview Questions
Certain languages, for example Clojure , Common Lisp , or Cython are dynamically type-checked by default, but allow programs to opt into static type checking by providing optional annotations. Hosted, Enterprise, and ISV licensing; free and paid versions. Retrieved August 19, Correlation engine handles both server-side such as session id and client-side such as time, date dynamic values - replaced automatically to create unique values for each script run. Conversely, some very old techniques in the static world, and some very new techniques in the dynamic world put you in a world of pain by taking downsides from both camps.
As soon as you go for objects, there will be second stage of refactoring to achieve polymorphism, responsibility and setting proper state. Just because that approach is too OO. If I would look at my example, a static class with create methods and methods to change the status, and convert this to your approach, fully OO that would mean: Instantiate an object with the key, call the create methods which prepares the records to save to the table later on.
Some update methods to set different statusses and on and everything would be done in the attributes. But if I would do this in mass, it would be less readable and I would always get everything out of objects, while otherwise I can call my static create methods and append this to a large internal table.
Do you also have experiences anti-oo or better said, people not willing to learn oo or postpone learning oo as long as possible. As a customer developer, we have very little outside development. And when we do, they must code within our standards, However, we do change and update our standards every few years well I instigate most of the changes usually by introducing new functionality.
Too much abstraction and little documentation not availible in your language!?! If you want to sell to a customer, make it easy for them to understand. Make it simple for them to use. Make it easy to maintain.
Flexibility — We are a US state government. Anything that is not straightforward, or easy to understand or simple is really wasted and takes up space. I want to know what the data is, where it came from, and how the result occurred. And I take the time to review it with my QA reviewer so they understand by using this particular OO code, I have made an improvement. Then, they do suggest using this in other programs, and it becomes a de facto standard.
The design you are thinking for each database record is Kind of Persistent Objects. When using the Persistent objects, you create setters and getter methods. Each field in your table which you want to update would become and instance attribute of your Persistent Object.
You keep on collecting the persistent object for each row in the context. Mainly the lack of Object services to access the tables and retrieve the information from DB tables. As you have noted, they would be performance intensive as well. That is using kind of State mechanism to handle each record. It would generate objects for Header, for each item, for each schedule line item, etc. At save, it would check the state of each object to decide on update. Agree that it would be difficult for procedural IT people to understand.
For developers, we should keep our Technical Design document up-to-date with the current design. Including UMLs would be a great idea.
As long as the developers can read UML, they would be able to understand it easily. For functional teams, they would need to keep up their skill to get used to it. But, as I mentioned in my reply to Wouter , they should be able to understand the design if the TD is well up-to-date. But as that software evolves, we would start reaping the benefits of that. You only care about setting the BAPI parameters from your class properly. Another example could be a report — two options — Summary and Details.
We, as an audience, get to learn a lot by reading your articles. Regarding new dimension topics — I have them lined up and they would be coming up soon. Comments on this Post are now closed.
If you have something important to share, you can always contact me. Get notified of the new post, right into your inbox. Override Redefine Static Method? While one controlled experiment showed an increase in developer productivity for duck typing in single developer projects,  other controlled experiments on API usability show the opposite.
Many type systems have been created that are specialized for use in certain environments with certain types of data, or for out-of-band static program analysis. Frequently, these are based on ideas from formal type theory and are only available as part of prototype research systems.
Dependent types are based on the idea of using scalars or values to more precisely describe the type of some other value. We can then define typing rules such as the following rule for matrix multiplication:.
A variant of ML called Dependent ML has been created based on this type system, but because type checking for conventional dependent types is undecidable , not all programs using them can be type-checked without some kind of limits. Dependent ML limits the sort of equality it can decide to Presburger arithmetic.
Other languages such as Epigram make the value of all expressions in the language decidable so that type checking can be decidable. However, in general proof of decidability is undecidable , so many programs require hand-written annotations that may be very non-trivial.
As this impedes the development process, many language implementations provide an easy way out in the form of an option to disable this condition. This, however, comes at the cost of making the type-checker run in an infinite loop when fed programs that do not type-check, causing the compilation to fail. Linear types , based on the theory of linear logic , and closely related to uniqueness types , are types assigned to values having the property that they have one and only one reference to them at all times.
Normally this is not possible, as such mutations could cause side effects on parts of the program holding other references to the object, violating referential transparency. They are also used in the prototype operating system Singularity for interprocess communication, statically ensuring that processes cannot share objects in shared memory in order to prevent race conditions.
The Clean language a Haskell -like language uses this type system in order to gain a lot of speed compared to performing a deep copy while remaining safe. Intersection types are types describing values that belong to both of two other given types with overlapping value sets.
For example, in most implementations of C the signed char has range to and the unsigned char has range 0 to , so the intersection type of these two types would have range 0 to Such an intersection type could be safely passed into functions expecting either signed or unsigned chars, because it is compatible with both types. Intersection types are useful for describing overloaded function types: In a subclassing hierarchy, the intersection of a type and an ancestor type such as its parent is the most derived type.
The intersection of sibling types is empty. The Forsythe language includes a general implementation of intersection types. A restricted form is refinement types. Union types are types describing values that belong to either of two types. For example, in C, the signed char has a to range, and the unsigned char has a 0 to range, so the union of these two types would have an overall "virtual" range of to that may be used partially depending on which union member is accessed.
Any function handling this union type would have to deal with integers in this complete range. More generally, the only valid operations on a union type are operations that are valid on both types being unioned.
C's "union" concept is similar to union types, but is not typesafe, as it permits operations that are valid on either type, rather than both. Union types are important in program analysis, where they are used to represent symbolic values whose exact nature e.
In a subclassing hierarchy, the union of a type and an ancestor type such as its parent is the ancestor type. The union of sibling types is a subtype of their common ancestor that is, all operations permitted on their common ancestor are permitted on the union type, but they may also have other valid operations in common. Existential types are frequently used in connection with record types to represent modules and abstract data types , due to their ability to separate implementation from interface.
This could be implemented in different ways; for example:. These types are both subtypes of the more general existential type T and correspond to concrete implementation types, so any value of one of these types is a value of type T. Given a value "t" of type "T", we know that "t. This gives flexibility for choosing types suited to a particular implementation while clients that use only values of the interface type—the existential type—are isolated from these choices.
In general it's impossible for the typechecker to infer which existential type a given module belongs to. The simplest solution is to annotate every module with its intended type, e.
Although abstract data types and modules had been implemented in programming languages for quite some time, it wasn't until that John C. Mitchell and Gordon Plotkin established the formal theory under the slogan: Gradual typing is a type system in which variables may be typed either at compile-time which is static typing or at run-time which is dynamic typing , allowing software developers to choose either type paradigm as appropriate, from within a single language.
The consistency relation is symmetric but not transitive. Many static type systems, such as those of C and Java, require type declarations: The programmer must explicitly associate each variable with a specific type.
Others, such as Haskell's, perform type inference: The compiler draws conclusions about the types of variables based on how programmers use those variables. Thus, any call to f elsewhere in the program that specifies a non-numeric type such as a string or list as an argument would signal an error.
Numerical and string constants and expressions in code can and often do imply type in a particular context. For example, an expression 3. Type inference is in general possible, if it is decidable in the type theory in question. Moreover, even if inference is undecidable in general for a given type theory, inference is often possible for a large subset of real-world programs. Most Haskell compilers allow arbitrary-rank polymorphism as an extension, but this makes type inference undecidable.
Type checking is decidable, however, and rank-1 programs still have type inference; higher rank polymorphic programs are rejected unless given explicit type annotations. Some languages like Perl 6 or C have a unified type system. Every type in C inherits from the Object class. Java has several primitive types that are not objects. Java provides wrapper object types that exist together with the primitive types so developers can use either the wrapper object types or the simpler non-object primitive types.
A type-checker for a statically typed language must verify that the type of any expression is consistent with the type expected by the context in which that expression appears. For example, in an assignment statement of the form x: This notion of consistency, called compatibility , is specific to each programming language. If the type of e and the type of x are the same, and assignment is allowed for that type, then this is a valid expression.
Thus, in the simplest type systems, the question of whether two types are compatible reduces to that of whether they are equal or equivalent. Different languages, however, have different criteria for when two type expressions are understood to denote the same type.
These different equational theories of types vary widely, two extreme cases being structural type systems , in which any two types that describe values with the same structure are equivalent, and nominative type systems , in which no two syntactically distinct type expressions denote the same type i. In languages with subtyping , the compatibility relation is more complex.
In particular, if A is a subtype of B , then a value of type A can be used in a context where one of type B is expected, even if the reverse is not true. Like equivalence, the subtype relation is defined differently for each programming language, with many variations possible. The presence of parametric or ad hoc polymorphism in a language may also have implications for type compatibility.
From Wikipedia, the free encyclopedia. This article is about type systems from the point-of-view of computer programming. For a theoretical formulation, see type theory. This article has multiple issues. Please help improve it or discuss these issues on the talk page. Learn how and when to remove these template messages. This article includes a list of references , but its sources remain unclear because it has insufficient inline citations.
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July Learn how and when to remove this template message. Dynamic programming language and Interpreted language. Strong and weak typing. Flag bits specify the contents of a memory location. Instruction, data type, and functions are specified by a 3 bit code in addition to its 48 bit contents. Retrieved 26 May At last we conclude that in functional testing functionality of the module is tested and structure is not considered.
It is performed, based on user's perspective. These tests ensure that the system does what users are expecting it to do. Anonymous August 17, at 8: Mbalie Keswa September 6, at 4: Anonymous December 24, at 3: Anonymous December 28, at 2: Anonymous January 19, at Anonymous January 29, at Anonymous February 6, at 7: Anonymous March 27, at Rajiullah Shah May 7, at 6: Anonymous July 8, at Anonymous July 14, at 1: Anonymous July 27, at 8: Muskaan Sharma July 28, at 9: Lydia Justin July 31, at 4: