openmethods

This module implements fast open multi-_methods.

Open _methods are like virtual functions, except that they are free functions, living outside of any class. Multi-_methods can take into account the dynamic types of more than one argument to select the most specialized variant of the function.

This implementation uses compressed dispatch tables to deliver a performance similar to ordinary virtual function calls, while minimizing the size of the dispatch tables in presence of multiple virtual arguments.

Synopsis of openmethods:

1 
2 import openmethods; // import lib
3 mixin(registerMethods); // once per module - don't forget!
4 
5 interface  Animal {}
6 class Dog : Animal {}
7 class Pitbull : Dog {}
8 class Cat : Animal {}
9 class Dolphin : Animal {}
10 
11 // open method with single argument <=> virtual function "from outside"
12 string kick(virtual!Animal);
13 
14 @method // implement 'kick' for dogs
15 string _kick(Dog x) // note the underscore
16 {
17   return "bark";
18 }
19 
20 @method("kick") // use a different name for specialization
21 string notGoodIdea(Pitbull x)
22 {
23   return next!kick(x) ~ " and bite"; // aka call 'super'
24 }
25 
26 // multi-method
27 string meet(virtual!Animal, virtual!Animal);
28 
29 // 'meet' implementations
30 @method
31 string _meet(Animal, Animal)
32 {
33   return "ignore";
34 }
35 
36 @method
37 string _meet(Dog, Dog)
38 {
39   return "wag tail";
40 }
41 
42 @method
43 string _meet(Dog, Cat)
44 {
45   return "chase";
46 }
47 
48 void main()
49 {
50   updateMethods(); // once per process - don't forget!
51 
52   import std.stdio;
53 
54   Animal hector = new Pitbull, snoopy = new Dog;
55   writeln("kick snoopy: ", kick(snoopy)); // bark
56   writeln("kick hector: ", kick(hector)); // bark and bite
57 
58   Animal felix = new Cat, flipper = new Dolphin;
59   writeln("hector meets felix: ", meet(hector, felix)); // chase
60   writeln("hector meets snoopy: ", meet(hector, snoopy)); // wag tail
61   writeln("hector meets flipper: ", meet(hector, flipper)); // ignore
62 }

Members

Aliases

MethodErrorHandler alias MethodErrorHandler = void function(MethodError error): Undocumented in source.
VirtualType alias VirtualType(T : virtual!U, U) = U: Undocumented in source.

Classes

MethodError class MethodError: Information passed to the error handler function.
virtual class virtual(T): Mark a parameter as virtual, and declare a method.

Enums

IsVirtual eponymoustemplate IsVirtual(T): Undocumented in source.
IsVirtual eponymoustemplate IsVirtual(T : virtual!U, U): Undocumented in source.

Functions

TypeIds auto TypeIds(): Undocumented in source. Be warned that the author may not have intended to support it.
_registerMethods string _registerMethods(): Undocumented in source. Be warned that the author may not have intended to support it.
defaultMethodErrorHandler void defaultMethodErrorHandler(MethodError error): Undocumented in source. Be warned that the author may not have intended to support it.
needUpdateMethods bool needUpdateMethods(): Undocumented in source. Be warned that the author may not have intended to support it.
next auto next(T args): Call the next most specialized override if it exists. In other words, call the override that would have been called if this one had not been defined.
registerMethods auto registerMethods(string moduleName): Used as a string mixin: register the methods declaration and definitions in the current module.
setMethodErrorHandler void function(MethodError error) setMethodErrorHandler(void function(MethodError error) handler): Set the function that is called if a method cannot be called with the arguments. Default is to abort the program.
updateMethods void updateMethods(): Update the runtime dispatch tables. Must be called once before calling any method. Typically this is done at the beginning of main.

Mixin templates

_registerSpecs mixintemplate _registerSpecs(alias MODULE): Undocumented in source.

Structs

Method struct Method(string id, string Mptr, R, T...): Undocumented in source.
MethodTag struct MethodTag: Undocumented in source.
Runtime struct Runtime: Undocumented in source.
method struct method: Used as an attribute: add an override to a method.
mptr struct mptr: Undocumented in source.

Templates

CallParams template CallParams(T...): Undocumented in source.
VirtualArity template VirtualArity(QP...): Undocumented in source.
castArgs template castArgs(T...): Undocumented in source.

Variables

errorHandler MethodErrorHandler errorHandler;: Undocumented in source.
hasVirtualParameters bool hasVirtualParameters(alias F);: Undocumented in source.

openmethods

Members

Aliases

Classes

Enums

Functions

Mixin templates

Structs

Templates

Variables

Meta

Source

License

Copyright

Authors