Difference between revisions of "pas2js Generics"
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==Working== | ==Working== | ||
− | * | + | * generic record |
− | * | + | * specialize: |
− | * | + | ** ObjFPC: ''type TFoo = specialize TGen<word>;'' |
+ | ** Delphi: ''type TFoo = TGen<word>;'' | ||
+ | ** ObjFPC anonymous: ''var r: specialize TBird<word>;'' | ||
+ | ** Delphi: anonymous ''var r: TBird<word>;'' | ||
+ | * generic class | ||
+ | ** specialize in ancestor type | ||
+ | ** forward generic class | ||
+ | * generic external class | ||
+ | * generic array | ||
+ | * record/class field | ||
+ | * property | ||
+ | * method (not confused with generic method) | ||
+ | * for-loop, if-then-else, repeat-until, while-do, try-finally, try-except | ||
+ | * some assignments | ||
+ | * primitive expression like identifiers and constants | ||
+ | * operators: +, - | ||
+ | * constraints: | ||
+ | ** keyword ''record'', keyword ''class'' checked at specialization | ||
+ | ** class type checked at specialization | ||
==ToDos== | ==ToDos== |
Revision as of 10:32, 13 August 2019
Overview
Working
- generic record
- specialize:
- ObjFPC: type TFoo = specialize TGen<word>;
- Delphi: type TFoo = TGen<word>;
- ObjFPC anonymous: var r: specialize TBird<word>;
- Delphi: anonymous var r: TBird<word>;
- generic class
- specialize in ancestor type
- forward generic class
- generic external class
- generic array
- record/class field
- property
- method (not confused with generic method)
- for-loop, if-then-else, repeat-until, while-do, try-finally, try-except
- some assignments
- primitive expression like identifiers and constants
- operators: +, -
- constraints:
- keyword record, keyword class checked at specialization
- class type checked at specialization
ToDos
- Delphi type overload, e.g. type TArr = array of word; TArr<T> = array of T; TArr<T,S> = record i:T; j:S end;
- cascaded specialize: TBird<word>.TWing<byte>
- nested specialize: TBird<TWing<byte>>
- anonymous type in specialize: TBird<array of word>
- generic class:
- default classname "TTest<System.Longint>"
- pas2js classname "TTest$G1" and overloads
- descendants cannot refer to type parameters of ancestors
- members can refer to itself without parameters:
- enumtype inside generic is not propagated
- nested generic: allowed by Delphi, not allowed by FPC
- method implementation
- Delphi: must repeat type params, can omit constraints
- FPC: must not repeat type params
- forward class (FPC does support it yet)
- generic record:
- generic interface:
- generic array:
- generic static array: Note: delphi wiki says "no static arrays", but 10.3 compiles it, see http://docwiki.embarcadero.com/RADStudio/Rio/en/Declaring_Generics
- generic procedural type:
- generic function (aka parametrized method):
- Delphi does not allow global generic functions, only generic methods
- methods: virtual, message, constructor and destructors cannot have type parameters
- constraints:
- "class", "record", "constructor" (class+default constructor, can be combined with class)
- multiple interface types
- one class type (Delphi: not TObject)
- forward class must repeat constraints
- specialize method:
- explicitly specifying Fly<word>(aWord)
- automatic inferring types Fly(aWord), $modeswitch implicitfunctionspecialization MyProc(1) calls MyProc<T>(a: T)
- specialized proc types can assign normal proc
- Statements:
- specialize (cloning) all kinds of statements and expressions
- inline specialization
- Delphi: TFoo<Integer>.Create
- FPC: specialize TFoo<Integer>.Create
- T is TFoo<Integer>
- T as TFoo<Integer>
- TFoo<Integer>(expr)
- "obj is T": allowed with constraint "class" or class type
- typecast T(): allowed with constraint "class" or class type
- typeinfo(T)
- using implementation function in generic function:
- Delphi: Error: Method of parameterized type declared in interface section must not use local symbol '%s'
- FPC: Error: Global Generic template references static symtable
- anInt:=GenericVar
- Delphi: always Error: Incompatible types: 'Integer' and 'T'
- FPC: allowed for valid combinations -> operators are checked on specialization, Note: because of implementation cross uses, check must be delayed until used unit implementation is complete
- call
- Delphi: must fit the constraint. For example without constraint it only fits untyped args.
- FPC: if only one function in scope preselect it, overloads are selected by constraints alone. Later checked by specialization.