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49-539: The definition published by the FSF in February 1986 had two points: The word "free" in our name does not refer to price; it refers to freedom. First, the freedom to copy a program and redistribute it to your neighbors, so that they can use it as well as you. Second, the freedom to change a program, so that you can control it instead of it controlling you; for this, the source code must be made available to you. In 1996, when

98-462: A source-code editor that can alert the programmer to common errors. Modification often includes code refactoring (improving the structure without changing functionality) and restructuring (improving structure and functionality at the same time). Nearly every change to code will introduce new bugs or unexpected ripple effects , which require another round of fixes. Code reviews by other developers are often used to scrutinize new code added to

147-430: A trade secret . Proprietary, secret source code and algorithms are widely used for sensitive government applications such as criminal justice , which results in black box behavior with a lack of transparency into the algorithm's methodology. The result is avoidance of public scrutiny of issues such as bias. Access to the source code (not just the object code) is essential to modifying it. Understanding existing code

196-454: A better size measure for software than LOC. In that it is based on the specification of the software and thereby aims at measuring the size of its functionality rather than the code itself. The reason is that the size of the code not only depends on the size of the functionality but also on the capability of the programmer: better programmers will produce less code for the same functionality. The function points have undergone several redesigns over

245-431: A computer, at base, only understands machine code , source code must be translated before a computer can execute it. The translation process can be implemented three ways. Source code can be converted into machine code by a compiler or an assembler . The resulting executable is machine code ready for the computer. Alternatively, source code can be executed without conversion via an interpreter . An interpreter loads

294-638: A non-manufacturing context. It is commonly agreed that the nature of knowledge work fundamentally differs from manual work and, hence, factors besides the simple output/input ratio need to be taken into account, e.g. quality, timeliness, autonomy, project success, customer satisfaction and innovation. However, the research communities in neither discipline have been able to establish broadly applicable and accepted means for productivity measurement yet. The same holds for more specific area of programming productivity. Profitability and performance are closely linked and are, in fact, often confused. However, as profitability

343-429: A number of productivity factors but also points out that for each project a different set of factors are influential. These factors can form a basis for productivity assessments and for comparison with industrial averages. This is one such list: The 20 factors whose quantified impacts on software projects have been determined from historical data are the following: Function points were proposed in 1977 by Albrecht as

392-444: A project. The purpose of this phase is often to verify that the code meets style and maintainability standards and that it is a correct implementation of the software design . According to some estimates, code review dramatically reduce the number of bugs persisting after software testing is complete. Along with software testing that works by executing the code, static program analysis uses automated tools to detect problems with

441-406: A specific platform, source code can be ported to a different machine and recompiled there. For the same source code, object code can vary significantly—not only based on the machine for which it is compiled, but also based on performance optimization from the compiler. Most programs do not contain all the resources needed to run them and rely on external libraries . Part of the compiler's function

490-422: A straightforward metric of productivity is simple: how many units of a product of specified quality is produced by which costs. For intellectual work, productivity is much trickier. How do we measure the productivity of authors, scientists, or engineers? Due to the rising importance of knowledge work (as opposed to manual work), many researchers tried to develop productivity measurement means that can be applied in

539-468: A straightforward relation between the number of units produced and the number of units consumed. Non-manufacturing industries usually use man-hours or similar units to enable comparison between outputs and inputs. One basic agreement is that the meaning of productivity and the means for measuring it vary depending on what context is under evaluation. In a manufacturing company the possible contexts are: As long classical production processes are considered

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588-442: Is an overarching term that can refer to a code's correct and efficient behavior, its reusability and portability , or the ease of modification. It is usually more cost-effective to build quality into the product from the beginning rather than try to add it later in the development process. Higher quality code will reduce lifetime cost to both suppliers and customers as it is more reliable and easier to maintain . Maintainability

637-452: Is frequently cited as a contributing factor to the maturation of their programming skills. Some people consider source code an expressive artistic medium . Source code often contains comments —blocks of text marked for the compiler to ignore. This content is not part of the program logic, but is instead intended to help readers understand the program. Companies often keep the source code confidential in order to hide algorithms considered

686-699: Is highly impractical. In July 1997, Bruce Perens published the Debian Free Software Guidelines . A definition based on the DFSG was also used by the Open Source Initiative (OSI) under the name " The Open Source Definition ". Despite the philosophical differences between the free software movement and the open-source-software movement , the official definitions of free software by the FSF and of open-source software by

735-431: Is it not only important to track the costs in a software project but also the real earned value, i.e. the value for the customer. They explain that it is important to create the software business case and keep it up to date. In essence, value-based software engineering focuses on the customer value, mainly measured in monetary units. The famous book Peopleware: Productive Projects and Teams by de Marco and Lister brought

784-496: Is necessary to understand how it works and before modifying it. The rate of understanding depends both on the code base as well as the skill of the programmer. Experienced programmers have an easier time understanding what the code does at a high level. Software visualization is sometimes used to speed up this process. Many software programmers use an integrated development environment (IDE) to improve their productivity. IDEs typically have several features built in, including

833-631: Is that many software engineering courses do not emphasize it. Development engineers who know that they will not be responsible for maintaining the software do not have an incentive to build in maintainability. The situation varies worldwide, but in the United States before 1974, software and its source code was not copyrightable and therefore always public domain software . In 1974, the US Commission on New Technological Uses of Copyrighted Works (CONTU) decided that "computer programs, to

882-477: Is the quality of software enabling it to be easily modified without breaking existing functionality. Following coding conventions such as using clear function and variable names that correspond to their purpose makes maintenance easier. Use of conditional loop statements only if the code could execute more than once, and eliminating code that will never execute can also increase understandability. Many software development organizations neglect maintainability during

931-418: Is to link these files in such a way that the program can be executed by the hardware. Software developers often use configuration management to track changes to source code files ( version control ). The configuration management system also keeps track of which object code file corresponds to which version of the source code file. The number of lines of source code is often used as a metric when evaluating

980-408: Is usually defined as the ratio between revenue and cost Profitability = Revenue / Cost It has a wider scope than performance, i.e. the number of factors that influence profitability is greater than the number of factors than influence productivity. Particularly, profitability can change without any change to the productivity, e.g. due to external conditions like cost or price inflation. Besides that,

1029-443: Is usually explained informally as efficiency is doing things right and effectiveness is doing the right things . While there are numerous other definitions, there is a certain agreement that efficiency refers to the utilisation of resources and mainly influences the required input of the productivity ratio. Effectiveness on the other hand mainly influences the output of the productivity ratio as it usually has direct consequences for

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1078-480: The Balanced Scorecard do include productivity as a factor that is central but not unique. Other relevant factors are e.g. the customers’ or stakeholders’ perception of the company. Efficiency and effectiveness are terms that provide further confusion as they themselves are often mixed up and, additionally, efficiency is often confused with productivity. The difference between efficiency and effectiveness

1127-588: The OSI basically refer to the same software licences, with a few minor exceptions. While stressing these philosophical differences, the Free Software Foundation comments: The term "open source" software is used by some people to mean more or less the same category as free software. It is not exactly the same class of software: they accept some licences that we consider too restrictive, and there are free software licences they have not accepted. However,

1176-458: The compilers needed to translate the source code automatically into machine code that can be directly executed on the computer hardware . Source code is the form of code that is modified directly by humans, typically in a high-level programming language. Object code can be directly executed by the machine and is generated automatically from the source code, often via an intermediate step, assembly language . While object code will only work on

1225-419: The best consensus on the terminology. While there is no commonly agreed on definition of productivity, there appears to be an agreement that productivity describes the ratio between output and input: Productivity = Output / Input However, across the various disciplines different notions and, particularly, different measurement units for input and output can be found. The manufacturing industry typically uses

1274-426: The classic literature in non-software disciplines, especially in the manufacturing area, does not explicitly discuss the role of quality of the output in the productivity ratio. More recent works from non-manufacturing disciplines have a stronger focus on knowledge, office or white-collar work and hence increasingly discuss the role of quality with respect to quality. Drucker stresses the importance of quality for

1323-406: The customer. Effectiveness can be defined as "the ability to reach a desired output". Generally, it is assumed, that efficiency can be quantified, e.g. by utilization rates, considerably more easily than effectiveness. Tangen states: "Improvements in quality, other than the fact that no-fault products add to output levels, ought not to be included in the concept of productivity." However, most of

1372-400: The details of the hardware, instead being designed to express algorithms that could be understood more easily by humans. As instructions distinct from the underlying computer hardware , software is therefore relatively recent, dating to these early high-level programming languages such as Fortran , Lisp , and Cobol . The invention of high-level programming languages was simultaneous with

1421-426: The development phase, even though it will increase long-term costs. Technical debt is incurred when programmers, often out of laziness or urgency to meet a deadline, choose quick and dirty solutions rather than build maintainability into their code. A common cause is underestimates in software development effort estimation , leading to insufficient resources allocated to development. A challenge with maintainability

1470-404: The differences in extension of the category are small: nearly all free software is open source, and nearly all open source software is free. Source code In computing , source code , or simply code or source , is a plain text computer program written in a programming language . A programmer writes the human readable source code to control the behavior of a computer . Since

1519-479: The evaluation of knowledge worker productivity: "Productivity of knowledge work therefore has to aim first at obtaining quality—and not minimum quality but optimum if not maximum quality. Only then can one ask: "What is the volume, the quantity of work?"" Saari captures the importance of quality with his extended formula for productivity: Total productivity = (Output quality and quantity)/(Input quality and quantity) However, it appears that these efforts to include

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1568-406: The extent that they embody an author's original creation, are proper subject matter of copyright". Proprietary software is rarely distributed as source code. Although the term open-source software literally refers to public access to the source code , open-source software has additional requirements: free redistribution, permission to modify the source code and release derivative works under

1617-432: The gnu.org website was launched, "free software" was defined referring to "three levels of freedom" by adding an explicit mention of the freedom to study the software (which could be read in the two-point definition as being part of the freedom to change the program). Stallman later avoided the word "levels", saying that all of the freedoms are needed, so it is misleading to think in terms of levels. Finally, another freedom

1666-442: The group, divisional, organizational and national levels. Due to this diversity, there is no clear-cut definition of productivity and its influencing factors, although research has been conducted for more than a century. Like in software engineering, this lack of common agreement on what actually constitutes productivity, is perceived as a major obstacle for a substantiated discussion of productivity. The following definitions describe

1715-417: The importance of people-related factors to the attention of a broader audience. They collected in many software projects experiences with good and bad management practice that have an influence on the productivity of the team. They and others showed that these are the decisive issues in software engineering but were only able to describe them anecdotally. There are probably a large number of factors influencing

1764-475: The instructions can be carried out. After being compiled, the program can be saved as an object file and the loader (part of the operating system) can take this saved file and execute it as a process on the computer hardware. Some programming languages use an interpreter instead of a compiler. An interpreter converts the program into machine code at run time , which makes them 10 to 100 times slower than compiled programming languages. Software quality

1813-405: The interdependency between productivity and profitability is usually delayed, i.e. gains in productivity are rarely reflected in immediate profitability gains are more likely realized on the long-term. The term performance is even broader than productivity and profitability and covers a plethora of factors that influence a company's success. Hence, well-known performance controlling instruments like

1862-425: The model is based on function points and finally source lines of code (LOC). The limitations of LOC as a productivity measure are well-known. Jones is the author of a series of books on software productivity. Besides several theoretical considerations his main contribution is the systematic provision and integration of a large amount of data relevant for productivity analyses. In at least two of his books, he gives

1911-426: The processor). Machine language was difficult to debug and was not portable between different computer systems. Initially, hardware resources were scarce and expensive, while human resources were cheaper. As programs grew more complex, programmer productivity became a bottleneck. This led to the introduction of high-level programming languages such as Fortran in the mid-1950s. These languages abstracted away

1960-465: The productivity of computer programmers, the economic value of a code base, effort estimation for projects in development, and the ongoing cost of software maintenance after release. Source code is also used to communicate algorithms between people – e.g., code snippets online or in books. Computer programmers may find it helpful to review existing source code to learn about programming techniques. The sharing of source code between developers

2009-415: The programming productivity of individuals and teams. For example, the used software development process probably influences the effectiveness and efficiency of a team. The personalities of software programmers influence the used coding styles which, in turn, influence the productivity of the programmers. In 2007, the xkcd comic popularized the concept of a Ballmer Peak —that a programmer, with just

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2058-407: The quality in the determination of productivity did not lead to an operationalizable concept yet. It currently remains unclear how to quantify the vague terms “Output quality and quantity” as well as “Input quality and quantity”, let alone to calculate the ratio. In software development things are more complicated than in the production of goods. Software development is an engineering process. Boehm

2107-414: The ratio between the quantity of software produced and the cost spent for it. Here the delicacy lies in finding a reasonable way to define software quantity. Productivity is an important topic investigated in disciplines as various as manufacturing, organizational psychology, industrial engineering, strategic management, finance, accounting, marketing and economics. Levels of analysis include the individual,

2156-452: The same license, and nondiscrimination between different uses—including commercial use. The free reusability of open-source software can speed up development. Programmer productivity Programming productivity (also called software productivity or development productivity ) describes the degree of the ability of individual programmers or development teams to build and evolve software systems. Productivity traditionally refers to

2205-432: The source code into memory. It simultaneously translates and executes each statement . A method that combines compilation and interpretation is to first produce bytecode . Bytecode is an intermediate representation of source code that is quickly interpreted. The first programmable computers, which appeared at the end of the 1940s, were programmed in machine language (simple instructions that could be directly executed by

2254-414: The source code. Many IDEs support code analysis tools, which might provide metrics on the clarity and maintainability of the code. Debuggers are tools that often enable programmers to step through execution while keeping track of which source code corresponds to each change of state. Source code files in a high-level programming language must go through a stage of preprocessing into machine code before

2303-613: The years mainly driven by the International Function Point User Group (IFPUG). This group is large with over 1200 companies as member which shows the rather strong acceptance of this measure. However, in many domains it still lacks practical application because it is often conceived as only applicable to business information systems. Several researchers proposed economic-driven or value-based software engineering as an important paradigm in future software engineering research. Boehm and Huang point out that

2352-447: Was added, to explicitly say that users should be able to run the program. The existing freedoms were already numbered one to three, but this freedom should come before the others, so it was added as "freedom zero". The modern definition defines free software by whether or not the recipient has the following four freedoms: Freedoms 1 and 3 require source code to be available because studying and modifying software without its source code

2401-429: Was one of the first researchers that systematically approached the field of software productivity. His cost estimation model COCOMO - now COCOMO II - is standard software engineering knowledge. In this model, he defines a set of factors that influence productivity, such as the required reliability or the capability of the analysts. These factors have been widely reused in other similar productivity approaches. The rest of

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