Scripting Languages

Question 1

What is a scripting language?

Answer 1

A programming language that supports scripts: programs written for a special run-time environment that automate the execution of tasks that could alternatively be executed one-by-one by a human operator.

Question 2

Scripting languages are often ___ (rather than ____).

interpreted, compiled

Answer 2

Scripting languages are often interpreted, rather than compiled.

Question 3

What is a compiled language?

Answer 3

One where the program, once compiled, is expressed in the instructions of the target machine; this machine code is undecipherable by humans.

Question 4

What is an interpreted language?

Answer 4

One where the instructions are not directly executed by the target machine, but instead read and executed by some other program (which normally is written in the language of the native machine).

Question 5

How is code executed via compilation?

Answer 5

It is executed natively through the operating system after it is converted to machine code.

Question 6

How is code executed via interpolation?

Answer 6

It is evaluated line by line through a program which handles executing the code instead of the operating system itself.

Question 7

Can you easily classify a programming language as either compiled or interpreted?

Answer 7

Not usually- most programming languages have both compiled implementations and interpreted implementations. Languages are often referred to as one or the other for the sake of simplicity and clarity.

Question 8

What is the major advantage of compiled languages over interpreted languages?

Answer 8

their execution speed.

Question 9

Why are compiled languages usually faster than interpreted languages?

Answer 9

Because they are converted directly into machine code.

Question 10

Why do lower-level languages tend to be compiled?

Answer 10

Because efficiency is usually more of a concern than cross-platform support. Also, because compiled languages are converted directly into machine code, this gives the developer much more control over hardware aspects such as memory management and CPU usage.

Question 11

What are some examples of pure compiled languages?

Answer 11

C, C++, Erlang, Haskell, Rust, Go.

Question 12

What is a pitfall of a compiled language?

Answer 12

You need to manually compile a program in order to run it.

Question 13

What is a pitfall of a compiled language involving debugging?

Answer 13

While you debug the program, you need to recompile the program each time you want to test your new changes.

Question 14

Are compiled languages platform-independent?

Answer 14

No, the compiled machine code is specific to the language that is executing it.

Question 15

What is an example of a technology that is narrowing the execution time gap between interpreted and compiled languages?

Answer 15

just-in-time compilation.

Question 16

What is just-in-time compilation?

Answer 16

Compilation done during execution of a program- at run time- rather than prior to execution.

Question 17

What are some examples of interpreted languages?

Answer 17

PHP, Perl, Ruby and Python.

Question 18

What are some programming concepts that interpreted languages make easier?

Answer 18

Platform independence, reflection, dynamic typing, smaller executable program size and dynamic scoping.

Question 19

How does just-in-time compilation work?

Answer 19

it converts frequently-executed sequences of interpreted instruction into host machine code.

Question 20

What are bytecode languages?

Answer 20

a type of programming language that fall under the categories of both compiled and interpreted languages because they employ both compilation and interpretation to execute code.

Question 21

What are the most common examples of bytecode languages?

Answer 21

Java and the .Net framework.

Question 22

What is the first step in a bytecode language?

Answer 22

In a bytecode language, the first step is to compile the current program from its human-readable language into bytecode.

Question 23

What is bytecode?

Answer 23

Bytecode is a form of instruction set that is designed to be efficiently executed by an interpreter and is composed of compact numeric codes, constants, and memory references.

Question 24

Where is the bytecode passed after compilation?

Answer 24

the bytecode is passed to a virtual machine which acts as the interpreter, which then proceeds to interpret the code as a standard interpreter would.

Question 25

When is there a delay in bytecode languages?

Answer 25

there is a delay when the program is first run in order to compile the code into bytecode, but the execution speed is increased considerably compared to standard interpreted languages because the bytecode is optimized for the interpreter.

Question 26

What is the largest benefit of bytecode languages?

Answer 26

The largest benefit of bytecode languages is platform independence which is typically only available to interpreted languages, but the programs have a much faster execution speed than interpreted languages.

Question 27

Compiled languages in a nutshell.

Answer 27

Compiled languages are the most efficient type of programming language because they execute directly as machine code and can easily utilize more of the hardware specs of the running machine. In turn, this forces a significantly stricter coding style and a single program usually can’t be run on different operating systems.

Question 28

Interpreted languages in a nutshell.

Answer 28

Interpreted languages on the other hand offer much more diversity in coding style, are platform-independent, and easily allow for dynamic development techniques such as metaprogramming. However, interpreted languages execute much slower than compiled languages – though just-in-time compilation has been helping to speed this up.

Question 29

What is reflection (in computer science)?

Answer 29

Reflection is the ability of a computer program to examine, introspect, and modify its own structure and behavior at runtime.

Question 30

How is reflection generally used?

Answer 30

Reflection can be used for observing and modifying program execution at runtime. A reflection-oriented program component can monitor the execution of an enclosure of code and can modify itself according to a desired goal related to that enclosure. This is typically accomplished by dynamically assigning program code at runtime.

Question 31

How is reflection used in object-oriented programming?

Answer 31

In object-oriented programming languages such as Java, reflection allows inspection of classes, interfaces, fields and methods at runtime without knowing the names of the interfaces, fields, methods at compile time. It also allows instantiation of new objects and invocation of methods.

Question 32

How is reflection used in software testing?

Answer 32

It can be used for the runtime creation/instantiation of mock objects.

Question 33

What is a type system?

Answer 33

In programming languages, a type system is a set of rules that assign a property called type to various constructs a computer program consists of, such as variables, expressions, functions or modules.

Question 34

What is the main purpose of a type system?

Answer 34

To reduce possibilities for bugs in computer programs by defining interfaces between different parts of a computer program, and then checking that the parts have been connected in a consistent way.

Question 35

When does static typing occur?

Answer 35

At compile time.

Question 36

When does dynamic typing occur?

Answer 36

At run time.

Question 37

What is a domain-specific language (DSL)?

Answer 37

A domain-specific language (DSL) is a computer language specialized to a particular application domain. This is in contrast to a general-purpose language (GPL), which is broadly applicable across domains.

Question 38

What is a common DSL for web pages?

Answer 38

HTML

Question 39

What are some further DSL subdivisions?

Answer 39

domain-specific markup languages, domain-specific modeling languages, domain-specific programming languages.

Question 40

What has made the term DSL more popular?

Answer 40

the term “domain-specific language” has become more popular due to the rise of domain-specific modeling.

Question 41

What is the spectrum of scripting languages?

Answer 41

The spectrum of scripting languages ranges from very small and highly domain-specific languages to general-purpose programming languages used for scripting.