at:tutorial:appendix
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
at:tutorial:appendix [2008/07/08 11:47] – *edited tvcutsem | at:tutorial:appendix [2021/09/24 10:28] (current) – [Dynamic Variables] elisag | ||
---|---|---|---|
Line 1: | Line 1: | ||
- | ====== Appendix ====== | + | ====== Appendix: Libraries |
- | In the appendix, we explain useful libraries available to the AmbientTalk/ | + | In the appendix, we explain useful libraries available to the AmbientTalk/ |
+ | |||
+ | The Ambientalk standard library ('' | ||
===== Unit Testing Framework ===== | ===== Unit Testing Framework ===== | ||
Line 27: | Line 29: | ||
This will execute all '' | This will execute all '' | ||
- | Like in JUnit and SUnit, it is possible to define two methods named '' | + | Like in JUnit and SUnit, it is possible to define two methods named '' |
==== Assertions ==== | ==== Assertions ==== | ||
Line 82: | Line 84: | ||
It is also possible to use '' | It is also possible to use '' | ||
+ | |||
+ | <note tip> | ||
+ | See the [[distribution# | ||
+ | </ | ||
==== Test Suites ==== | ==== Test Suites ==== | ||
Line 95: | Line 101: | ||
The '' | The '' | ||
+ | |||
+ | ===== Basic Collections ===== | ||
+ | |||
+ | The modules ''/ | ||
+ | |||
+ | ==== Vector ==== | ||
+ | |||
+ | A vector is a dynamically resizable AmbientTalk table (aka array). Indexed reading from and writing to a vector is fast (O(1)). Adding elements to a vector is mostly fast, but sometimes requires a resize of the vector. Vectors support the traditional stack operations '' | ||
+ | |||
+ | Vectors may be created as follows: | ||
+ | |||
+ | < | ||
+ | import / | ||
+ | def v := Vector.new(10); | ||
+ | </ | ||
+ | |||
+ | The constructor optionally takes a comparator as a second argument. A comparator is a binary function returning a boolean whose job is to compare elements of the Vector. This comparator is used among others when sorting the vector. The Vector' | ||
+ | |||
+ | < | ||
+ | // returns the number of elements in the vector (not its capacity!) | ||
+ | length() | ||
+ | |||
+ | // returns whether the vector contains elements or not | ||
+ | isEmpty() | ||
+ | |||
+ | // is the vector at max. capacity? | ||
+ | atMaxCapacity() | ||
+ | |||
+ | // return idx'th element or raise an IndexOutOfBounds exception | ||
+ | at(idx) | ||
+ | |||
+ | // write idx'th element or raise IndexOutOfBounds exception | ||
+ | atPut(idx, val) | ||
+ | |||
+ | // iterate over the vector | ||
+ | each: iterator, returns nil | ||
+ | |||
+ | // map a unary function over the vector, returns a new vector | ||
+ | map: fun | ||
+ | |||
+ | // accumulate a function with a given starting value | ||
+ | inject: init into: accum; | ||
+ | |||
+ | // returns a new vector whose elements satisfy " | ||
+ | filter: cond; | ||
+ | |||
+ | // implode a vector of character strings into one text string | ||
+ | implode() | ||
+ | |||
+ | // join a vector of character strings together with the given string | ||
+ | join(txt) | ||
+ | |||
+ | // returns a range [start, | ||
+ | select(start, | ||
+ | |||
+ | // appends an element to the back of the vector. Returns the vector itself | ||
+ | add(element) | ||
+ | // alias for add(element) | ||
+ | << | ||
+ | |||
+ | // insert an element at a given position, causing subsequent elements to shift one pos to the right. Returns this vector | ||
+ | insert(atPos, | ||
+ | |||
+ | // delete the element at the given position, shifts all following elements one pos to the left. Returns the value of the element at the deleted position. | ||
+ | delete(atPos) | ||
+ | |||
+ | // adds elements to the back of the vector | ||
+ | push(element) | ||
+ | |||
+ | // deletes elements from the back of the vector | ||
+ | pop() | ||
+ | |||
+ | // return the index of the first element matching the unary predicate or nil if none is found | ||
+ | find: filter | ||
+ | |||
+ | // remove the given element from the vector, return true if the element was actually found and deleted, false otherwise | ||
+ | remove(elt, cmp := defaultComparator) | ||
+ | |||
+ | // remove all objects for which filter(elt) returns true | ||
+ | removeAll: filter | ||
+ | |||
+ | // destructively appends otherVector to self. Returns this vector | ||
+ | addAll(otherVector) | ||
+ | |||
+ | // empties the vector | ||
+ | clear() | ||
+ | |||
+ | // Return a new vector whose elements form the set-union of all elements in self U otherVector | ||
+ | union(otherVector, | ||
+ | |||
+ | // Return a new vector whose elements form the set-intersection of all elements in self ^ otherVector | ||
+ | intersection(otherVector, | ||
+ | |||
+ | // Return a new vector whose elements form the set-difference of self \ otherVector | ||
+ | difference(otherVector, | ||
+ | |||
+ | // Quicksort the vector in-place. The comparator defines the ordering among elements. | ||
+ | sort(cmp := { |e1,e2| e1 < e2 }) | ||
+ | |||
+ | // Turn the vector into a set without duplicates in O(nlogn + n) | ||
+ | // The vector' | ||
+ | uniq(cmp := defaultComparator, | ||
+ | |||
+ | // return an element drawn randomly using a uniform distribution from the array or raise an EmptyVector exception. | ||
+ | random() | ||
+ | |||
+ | // return a table containing all elements of the vector | ||
+ | asTable() | ||
+ | </ | ||
+ | |||
+ | The file '' | ||
+ | |||
+ | ==== List ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | The list module defines two styles to manipulate cons-cells: an object-oriented and a functional style. The object-oriented style represents cons-cells as '' | ||
+ | |||
+ | The functional style allows one to manipulate lists by means of the following functions: | ||
+ | |||
+ | < | ||
+ | cons(car, | ||
+ | car(conscell) -> the car | ||
+ | cdr(conscell) -> the cdr | ||
+ | list(@items) -> a cons-cell representing the head of a list | ||
+ | </ | ||
+ | |||
+ | Lists (cons-cells or the empty list) support the following operations: | ||
+ | |||
+ | < | ||
+ | // accessors for car and cdr | ||
+ | car() | ||
+ | cdr() | ||
+ | |||
+ | // the length of the list | ||
+ | length() | ||
+ | |||
+ | // whether the list is empty or not | ||
+ | isEmpty() | ||
+ | |||
+ | // returns the nth element of the list | ||
+ | nth(n) | ||
+ | |||
+ | // apply a unary function to each element of the list | ||
+ | each: fun | ||
+ | |||
+ | // apply a function to each element and its index in the list | ||
+ | // i.e. list.eachWithIndex: | ||
+ | eachWithIndex: | ||
+ | |||
+ | // map a unary function over the list, returning a new list | ||
+ | map: fun | ||
+ | |||
+ | // accumulate a value over a list | ||
+ | inject: init into: accum | ||
+ | |||
+ | // return a new list whose elements satisfy the unary predicate | ||
+ | filter: cond | ||
+ | |||
+ | // does the list contain the element? | ||
+ | contains(elt, | ||
+ | |||
+ | // implode or join a list of text strings | ||
+ | implode() | ||
+ | join(txt) | ||
+ | |||
+ | // drop the first n elements from the list | ||
+ | tail(n) | ||
+ | |||
+ | // prepend an element to the list | ||
+ | add(elt) | ||
+ | |||
+ | // insert an element in the list (functionally) | ||
+ | insert(atPos, | ||
+ | |||
+ | // return a new list where the element atPos is deleted | ||
+ | delete(atPos) | ||
+ | |||
+ | // functional append | ||
+ | append(aList) | ||
+ | |||
+ | // return the index of the first matching element, or nil if none is found | ||
+ | find: filter | ||
+ | |||
+ | // return the index in the list of the element or nil of not found | ||
+ | indexOf(elt, | ||
+ | |||
+ | // return a list where the given element is removed | ||
+ | remove(elt, cmp := DEFAULTCOMPARATOR) | ||
+ | |||
+ | // return a new list where all objects for which filter(elt) is true are removed | ||
+ | removeAll: filter | ||
+ | |||
+ | // convert the list into a table | ||
+ | asTable() | ||
+ | </ | ||
+ | |||
+ | The file '' | ||
+ | |||
+ | |||
+ | ===== Top-level functions ===== | ||
+ | |||
+ | The file '' | ||
+ | |||
+ | ==== Asynchronous control structures ==== | ||
+ | |||
+ | The '' | ||
+ | |||
+ | '' | ||
+ | < | ||
+ | loop: { | ||
+ | ... | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | An '' | ||
+ | < | ||
+ | whenTrue: booleanFuture then: { ... } else: { ... } | ||
+ | </ | ||
+ | |||
+ | Asynchronous while loop over future-type conditional: | ||
+ | < | ||
+ | asLongAs: { /* asynchronous computation returning a future */ } do: { ... } | ||
+ | </ | ||
+ | |||
+ | ==== Mobile code ==== | ||
+ | |||
+ | The function '' | ||
+ | |||
+ | < | ||
+ | def mobileAdder(x) { | ||
+ | script: { |n| x + n } carrying: [`x] | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | A call to '' | ||
+ | |||
+ | The constructor function '' | ||
+ | |||
+ | < | ||
+ | def foo := 42; | ||
+ | def i := isolate: { | ||
+ | ... | ||
+ | } passAs: { |foo| | ||
+ | / | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | The above code defines an isolate object '' | ||
+ | |||
+ | ===== Custom Exceptions ===== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | < | ||
+ | deftype FooException; | ||
+ | </ | ||
+ | |||
+ | Next, define a prototype exception object using the '' | ||
+ | |||
+ | < | ||
+ | def XFooException := createException(FooException); | ||
+ | </ | ||
+ | |||
+ | '' | ||
+ | |||
+ | < | ||
+ | raise: XFooException.new(" | ||
+ | </ | ||
+ | |||
+ | If your custom exception requires additional state, you can define it as an extension of the prototype exception. If you define a custom constructor, | ||
+ | |||
+ | < | ||
+ | deftype IndexOutOfBounds; | ||
+ | def XIndexOutOfBounds := createException(IndexOutOfBounds) with: { | ||
+ | def min; | ||
+ | def max; | ||
+ | def idx; | ||
+ | def init(min, max, idx) { | ||
+ | super^init(" | ||
+ | self.min := min; | ||
+ | self.max := max; | ||
+ | self.idx := idx; | ||
+ | }; | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | The exception module also exports an auxiliary function '' | ||
+ | |||
+ | ===== Language Extensions ===== | ||
+ | |||
+ | The files in the '' | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | =====Futures and Multifutures ===== | ||
+ | |||
+ | ==== Futures ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | The module exports the type tags '' | ||
+ | * Tagging an asynchronous message with '' | ||
+ | * Tagging a message with '' | ||
+ | * Tagging a message with '' | ||
+ | |||
+ | Messages can be automatically associated with a future by invoking the '' | ||
+ | |||
+ | The futures module also exports the function '' | ||
+ | |||
+ | Futures can also be created and resolved manually: | ||
+ | < | ||
+ | import / | ||
+ | def [fut, res] := makeFuture(); | ||
+ | when: someAsynchronousComputation() becomes: { |value| | ||
+ | res.resolve(value); | ||
+ | } | ||
+ | fut // return the future to a client | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | === Auxilary functions in the futures module ==== | ||
+ | |||
+ | The futures module also provides some auxiliary functions, of which '' | ||
+ | |||
+ | < | ||
+ | when: (group: [ a< | ||
+ | def [aResult, bResult] := values; | ||
+ | ... | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | Another useful auxilary function is '' | ||
+ | |||
+ | < | ||
+ | future: { |return| | ||
+ | // some computation | ||
+ | return(val) | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | This is actually equivalent to the slightly more verbose code: | ||
+ | |||
+ | < | ||
+ | def [fut,res] := makeFuture(); | ||
+ | try: { // some computation | ||
+ | res.resolve(val); | ||
+ | } catch: Exception using: { |e| res.ruin(e) } | ||
+ | fut; | ||
+ | </ | ||
+ | |||
+ | ==== Multifutures ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | A multifuture is constructed as follows: | ||
+ | < | ||
+ | def [mf, resolver] := makeMultiFuture(n, | ||
+ | </ | ||
+ | |||
+ | The parameter '' | ||
+ | |||
+ | A multifuture accepts the following listeners: | ||
+ | |||
+ | < | ||
+ | whenEach: multiFuture becomes: { |val| ... } | ||
+ | </ | ||
+ | |||
+ | The above listener is invoked whenever the future is resolved with a new value. Its code can thus be executed multiple times. | ||
+ | |||
+ | < | ||
+ | whenAll: multiFuture resolved: { |values| | ||
+ | ... | ||
+ | } ruined: { |exceptions| ... } | ||
+ | </ | ||
+ | |||
+ | The above listener is invoked if all results have been gathered (only possible if the maximum number of results is known) or when the '' | ||
+ | |||
+ | Note the following properties of multifutures: | ||
+ | * It is allowed to register a whenAll: | ||
+ | * As with futures, it is legal to send asynchronous messages to the multifuture, | ||
+ | * When a multifuture A is resolved with a multifuture B, all of B's eventual values/ | ||
+ | * A whenEach: | ||
+ | * Like with futures, multifutures can be explicitly created, e.g.: | ||
+ | < | ||
+ | * Multifutures can be attached to messages by annotating an asynchronous message with the @Gather(n) type tag. | ||
+ | * Adding a when: | ||
+ | |||
+ | The multifutures module also exports an abstraction known as a " | ||
+ | |||
+ | When the message sent to a multireference is annotated with @Due(t), the timeout is applied to the implicit multifuture, | ||
+ | |||
+ | |||
+ | ===== Leased Object References ===== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | < | ||
+ | The implementation of leased object references actually consists of two files: ''/ | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | |||
+ | Variations of these constructs are also provided to allow developers to specify the renewal time interval in renew-on-call leased references and the name(s) of the method(s) which trigger expiration of a single-call leased reference. | ||
+ | |||
+ | The '' | ||
+ | |||
+ | < | ||
+ | renew: leasedRef for: interval; // renews a lease | ||
+ | revoke: leasedRef; // revokes a lease | ||
+ | leaseTimeLeft: | ||
+ | when: lease expired: {...}; // trigger a closure when the lease expires | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | Finally, the '' | ||
+ | |||
+ | |||
+ | |||
+ | ===== TOTAM ===== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | Please have a look to [[: | ||
+ | |||
+ | ===== Dynamic Variables ===== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | A dynamic variable can be defined as follows: | ||
+ | < | ||
+ | def name := dynamicVariable: | ||
+ | </ | ||
+ | |||
+ | It can be read as follows: | ||
+ | < | ||
+ | ?name or name.value | ||
+ | </ | ||
+ | |||
+ | It can be assigned only within a limited dynamic scope, as follows: | ||
+ | < | ||
+ | with: name is: newval do: { code } | ||
+ | // or | ||
+ | name.is: newval in: { code } | ||
+ | </ | ||
+ | |||
+ | When '' | ||
+ | |||
+ | By convention, we prefix the names of dynamic variables with a '' | ||
+ | |||
+ | You can find more usage examples of dynamic variables in the unit test included in the file '' | ||
+ | |||
+ | ===== Ambient References ===== | ||
+ | |||
+ | Ambient references are defined in the module ''/ | ||
+ | |||
+ | < | ||
+ | import / | ||
+ | deftype Printer; | ||
+ | def printers := ambient: Printer; | ||
+ | </ | ||
+ | |||
+ | In the above code, '' | ||
+ | |||
+ | Ambient references ship with two so-called " | ||
+ | |||
+ | ===== Structural Types ===== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | A structural type can be branded with type tags. In this case, objects only conform to the type if they are structurally conformant **and** if they are tagged with the structural type's brands. | ||
+ | |||
+ | Use the '' | ||
+ | |||
+ | < | ||
+ | def PersonProtocol := protocol: { | ||
+ | def name; | ||
+ | def age; | ||
+ | } named: `Person; | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | < | ||
+ | def tom := object: { | ||
+ | def name := " | ||
+ | def age() { 24 }; | ||
+ | } implements: PersonProtocol; | ||
+ | </ | ||
+ | |||
+ | You can also create a protocol from an object: | ||
+ | < | ||
+ | |||
+ | You can test protocol conformance in either of two styles: | ||
+ | * '' | ||
+ | * '' | ||
+ | |||
+ | You can also force a '' | ||
+ | * '' | ||
+ | * '' | ||
+ | |||
+ | More usage examples of structural types can be found in the unit test defined in the file '' | ||
+ | |||
+ | ===== Traits ===== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | Using the '' | ||
+ | |||
+ | To define a " | ||
+ | < | ||
+ | trait: { | ||
+ | ... | ||
+ | } requiring: Protocol; | ||
+ | </ | ||
+ | |||
+ | The above code creates a trait that can only be composed into an object adhering to the specified protocol. To compose traits, use the following language construct: | ||
+ | |||
+ | < | ||
+ | object: { | ||
+ | use: { | ||
+ | import T1 exclude ...; | ||
+ | import T2 alias ...; | ||
+ | } | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | Note that the place where '' | ||
+ | |||
+ | Usage examples can be found in the unit tests in the file '' | ||
+ | |||
+ | ===== Utilities ===== | ||
+ | |||
+ | The files in the '' | ||
+ | |||
+ | |||
+ | ==== Timing Utilities ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | < | ||
+ | def subscription := when: timeoutPeriod elapsed: { | ||
+ | ... | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | The milliseconds used to define the timeout period must be provided as a Java '' | ||
+ | |||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | |||
+ | Additionally, | ||
+ | |||
+ | The timer module also defines a function '' | ||
+ | |||
+ | Finally, there is a variant of '' | ||
+ | |||
+ | < | ||
+ | def testAsyncNearbyPlayerReply(){ | ||
+ | def nearbyPlayers := // search 2 nearby player orjbects; | ||
+ | // wait a bit so that there are the 2 members. | ||
+ | when: 2.seconds elapsedWithFuture: | ||
+ | self.assertEquals(2, | ||
+ | } | ||
+ | }; | ||
+ | </ | ||
+ | |||
+ | |||
+ | ==== Logging Framework ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | Here's a typical example of how to use a logger: | ||
+ | < | ||
+ | import / | ||
+ | def log := makeLogger(" | ||
+ | log("a message", | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | The logging level determines which messages are shown on the output log. The available error levels are: '' | ||
+ | |||
+ | The output object is an object that understands '' | ||
+ | |||
+ | ==== Object Inspector ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | < | ||
+ | import / | ||
+ | inspect(o); | ||
+ | </ | ||
+ | |||
+ | This will pop up a graphical inspector on the object, listing the object' | ||
+ | |||
+ | ==== Symbiosis Utilities ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | < | ||
+ | long(anAmbientTalkNumber) -> aJavaLong | ||
+ | short(anAmbientTalkNumber) -> aJavaShort | ||
+ | float(anAmbientTalkFraction) -> aJavaFloat | ||
+ | byte(anAmbientTalkNumber) -> aJavaByte | ||
+ | </ | ||
+ | |||
+ | The module also defines the following function: | ||
+ | < | ||
+ | cast: obj into: Interface | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | ==== Miscellaneous ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | === Random Numbers === | ||
+ | |||
+ | The utility module defines functions for easily generating random numbers. Its implementation uses the random number generators from the underlying JVM. The following functions are the most useful: | ||
+ | |||
+ | < | ||
+ | // generate a random integer in the interval [min, max[ | ||
+ | def randomNumberBetween(min, | ||
+ | // generate a random fraction in the interval [min, max[ | ||
+ | def randomFractionBetween(min, | ||
+ | </ | ||
+ | |||
+ | === Custom Object Serialization === | ||
+ | |||
+ | The method '' | ||
+ | |||
+ | < | ||
+ | //inside a mirror | ||
+ | def instancevar := ...; | ||
+ | def pass() { | ||
+ | uponArrivalBecome: | ||
+ | // return object to become here | ||
+ | } | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | The function plays a role similar to '' |
at/tutorial/appendix.txt · Last modified: 2021/09/24 10:28 by elisag