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 the presence of multiple virtual arguments.

Synopsis of openmethods:

1 
2 import openmethods; // import lib
3 mixin(registerMethods); // mixin must be called after importing module
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.

Classes

MethodError class MethodError: Information passed to the error handler function.

Enums

_isNamedSpec eponymoustemplate _isNamedSpec(alias spec): Undocumented in source.
hasVirtualParameters eponymoustemplate hasVirtualParameters(alias F): Undocumented in source.

Functions

_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 method declarations and definitions in the current module.
setMethodErrorHandler MethodErrorHandler setMethodErrorHandler(MethodErrorHandler handler): Set the error handling function to be called if an open method cannot be called with the provided arguments. The default is to abort the program.
trace void trace(T args): Undocumented in source. Be warned that the author may not have intended to support it.
tracef void tracef(T args): Undocumented in source. Be warned that the author may not have intended to support it.
tracefln void tracefln(T args): Undocumented in source. Be warned that the author may not have intended to support it.
updateMethods Runtime.Metrics updateMethods(): Update the runtime dispatch tables. Must be called once before calling any methods. Typically this is done at the beginning of main.

Manifest constants

MptrInDeallocator enum MptrInDeallocator;: Undocumented in source.
MptrViaHash enum MptrViaHash;: Undocumented in source.

Mixin templates

Registrar mixintemplate Registrar(TheMethod, alias Spec): Undocumented in source.
_registerSpecs mixintemplate _registerSpecs(alias MODULE): Undocumented in source.
registerClasses mixintemplate registerClasses(Classes...): Undocumented in source.

Structs

Method struct Method(string Mptr, R, string ID, uint FA, string[] SCM, T...): Undocumented in source.
MethodTag struct MethodTag: Undocumented in source.
Runtime struct Runtime: Undocumented in source.
covariant struct covariant(T): Mark a parameter as covariant.
method struct method: Attribute: Add an override to a method.
mptr struct mptr: Attribute: Set the policy for storing and retrieving the method pointer (mptr).
virtual struct virtual(T): Mark a parameter as virtual, and declare a method.

Templates

MethodOf template MethodOf(alias Fun): Undocumented in source.
_specId template _specId(alias M, alias spec): Undocumented in source.
_specId template _specId(alias M, alias spec): Undocumented in source.
staticSlice template staticSlice(alias Pack, alias Positions): Undocumented in source.

Variables

errorHandler MethodErrorHandler errorHandler;: Undocumented in source.

openmethods

Members

Aliases

Classes

Enums

Functions

Manifest constants

Mixin templates

Structs

Templates

Variables

Meta

Source

License

Copyright

Authors