No Silver Bullet – Essence and Accident in Software Engineering Mike Ballou“There is no single development, in either technology or management technique, which by itself promises even one order-of- Mythical Man-Month: Essays on Software Engineering • In 1987, authored No Silver Bullet – Essence and Accident in Software Engineering“We hear desperate cries for a silver bullet – something to any.”Sources of Essential Difficulty“Let us consider the inherent properties of this irreducible essence of modern software systems: complexity, conformity, changeability, and invisibility.”Complexity

objects© 2023 Adobe. All Rights Reserved. Substance© 2023 Adobe. All Rights Reserved. Substance Essence© 2023 Adobe. All Rights Reserved. Objects and their values  Objects usually have a meaning that object with _numerator set to 1 and _denominator set to 2 represents the rational number ½.  The essence of a rational in this state is ½.© 2023 Adobe. All Rights Reserved. numerator_ =1, denominator_=2 denominator_=3 1/3 numerator_ =2, denominator_=4© 2023 Adobe. All Rights Reserved. 1/2 1/3 Substance Essence/Value© 2023 Adobe. All Rights Reserved. 460 480 500 520 540 560 580 600 620 x 0.0 0.1

{ FILE* f = fopen(p,"r"); // acquire // use f fclose(f); // release } Stroustrup - Essence - Fall'23 21 pointer Something representing a resourceRAII (Resource Acquisition Is Initialization) f(string s) { File_handle fh {s, "r“}; // now: ifstream fh{s} // use fh } Stroustrup - Essence - Fall'23 22 File handle FileOOP (1981 – 1984) • Encapsulation • Well-defined interfaces • Classes garbage collection would not release non-memory resources • why use a “naked” pointer? Stroustrup - Essence - Fall'23 41Resource Handles and Pointers • Use a cheap, safe “smart” pointer • A std::unique_ptr

DictionaryPermutation sort takes us to O(n!) — that’s right, factorial time. O(MG)! In essence, it is an unoptimised search through the permutations of the input values until it finds the one there can be nothing worse than permutation sort in terms of performance? Don’t be so sure. The essence of bogosort is to shuffle the values randomly until they are sorted. Kevlin Henney kevlinhenney

install:install() implements the logic behind conda create, conda install, conda update and conda remove. In essence, they all deal with the same task: changing which packages are present in an environment. If you plus their dependencies. The rationale behind this optimization trick can be found here. So, in essence, fetching the channel information means it can be expressed in pseudo-code like this: platform = even invoked. The second trick is done within the solver logic: an informed index reduction. In essence, the index (whether it’s current_repodata.json or full repodata.json) is pruned by the solver, trying

install:install() implements the logic behind conda create, conda install, conda update and conda remove. In essence, they all deal with the same task: changing which packages are present in an environment. If you plus their dependencies. The rationale behind this optimization trick can be found here. So, in essence, fetching the channel information means it can be expressed in pseudo-code like this: platform = even invoked. The second trick is done within the solver logic: an informed index reduction. In essence, the index (whether it’s current_repodata.json or full repodata.json) is pruned by the solver, trying

types from Delphi as well as some of its own. The programmer can declare his own types, which is in essence defining an identifier that can be used to denote this custom type when declaring variables further type identifier as the argument, and will return a correctly initialized variable of that type. In essence, it will zero out the whole variable. The following gives an example of its use: type TRecord = When a set-type constant must be entered in an expression, a set constructor must be given. In essence this is the same thing as when a type is defined, only there is no identifier to identify the set

'assets/allacrost_enemy_sprites/deceleon.png'); 7 this.game.load.image('demonic_essence', 'assets/allacrost_enemy_sprites/demonic_essence.png'); 8 this.game.load.image('dune_crawler', 'assets/allacrost_e image: 'daemarbora'}, 7 {name: 'Deceleon', image: 'deceleon'}, 8 {name: 'Demonic Essence', image: 'demonic_essence'}, 9 {name: 'Dune Crawler', image: 'dune_crawler'}, 10 {name: 'Green Slime' 'Deceleon', image: 'deceleon', maxHealth: 10}, 8 {name: 'Demonic Essence', image: 'demonic_essence', maxHealth: 15}, 9 {name: 'Dune Crawler', image: 'dune_crawler',

39 3.2 Function Object Wrapper CHAPTER 03: LANGUAGE RUNTIME ENHANCEMENTS std::function The essence of a Lambda expression is an object of a class type (called a closure type) that is similar to a Another common form is to pass in the three arguments std::string/std::smatch/std::regex. The essence of std::smatch is actually std::match_results. In the standard library, std::smatch is 67 Conclusion

the unprovable subgoal ⊢ false. The or.elim rule may seem counterintuitive at a first glance. In essence, it states that if we have a ∨ b, then to prove an arbitrary c, it sufces to prove c when a holds Functional–Logic Programming 51 Chapter 4 Functional Programming We take a closer look at the essence of typed functional programming: induc- tive types, proofs by induction, recursive functions, pattern often more convenient than using the introduction, elimination, and inversion principles of ⇒■ ⇒. In essence, we want structurally recursive equa- tions of the form �S ; T� = . . . �S� . . . �T� . . . �if