org.vishia.java2C.test
Interface Ifc

All Known Implementing Classes:

ExtendsImpl, ImplIfc

public interface Ifc

This interface should demonstrate the translation of Java-Interfaces to C. Visit the translated Ifc_Test.c and Ifc_Test.h.
The C-File contains code for:

• An implementation of all interface methods, which searches the appropriate method table of the interface inside the method table of the given instance, calling getMtbl_ObjectJc(...) and than calls the method dynamically. The user can call this method static linked, this method organized the dynmically call. ( Elsewhere the user can optimize and call via method table itself, Java2C translates such calls.)
• Reflection for the interface, contains the reference to the method table.
• The definition of the sign_Mtbl_... of this interface.
• The definition of all final static variables which are not defined as #define ...

• The typedef struct {...} of the interface type. The struct contains only union { ObjectJc object; } base;
• Typedef for the array type.
• extern declaration for reflection.
• extern declaration or #define ...for all static final values.
• Definition of MT_ method type of the interface methods.
• Declaration of head of interface methods to implement the dynamic call.
• extern Declaration of the sign_Mtbl_... of teh interface.
• Definition of the struct of the method table.

 extern const int32 constValue2_Ifc_Test;
 
 and defined in C-file as 
 
 const int32 constValue2_Ifc_Test = (constValue_Ifc_Test + 1) / 2 + 1;
 
 where the calculation is made at compile time.

constValue

static final int constValue

Example for a simple constant declared in java. Because it is fix and constant, it is translated in C as

 #define constValue_Ifc_Test 24
 

In this form the constant is used as an immediate value. A usage of this value is independent of the content of the interface' C-file. The same behavior is known for java in such cases: A substitution of a class file which contains another value for the same constant doesn't update the value in already-compiled class files.

See Also:

Constant Field Values

constString

static final java.lang.String constString

Example for a simple constant string literal. It is declared as

 extern const StringJc constString_Ifc_Test;
 

and defined in the C-File. It means, its value is updated if the interface is compiled and supplied newly. The string literal itself is stored only one time in the code. It is better as translating a #define constString_Ifc_Test "IfcTest".

See Also:

Constant Field Values

constValue2

static final int constValue2

Example for a calculated constant.At this time this constant is declared in Headerfile as

 extern const int32 constValue2_Ifc_Test;
 

and defined in C-file as

 const int32 constValue2_Ifc_Test = (constValue_Ifc_Test + 1) / 2 + 1;
 

where the calculation is made at compile time. It is possible because the input values are constants or constants defined per #define.
This strategy of compiling is limited. A constant defined in this form isn't able to use in C as constant input to built a adequate constant. The compiler may cause an error "initializer is not a constant" though the value is defined before. (testet with visual-Studio-6 C-compilation). Therefore it is better to build a

 #define constValue2_Ifc_Test (constValue_Ifc_Test + 1)/2 +1
 

The behavior should be changed in the next releases of Java2C.

See Also:

Constant Field Values

processIfcMethod

int processIfcMethod(int input)

Example for an interface method. This method is only abstract. In C it is a member of a so named method table. Therefore a method type definition is written in the Java2C-translated Headerfile:

 typedef int32 MT_processIfcMethod_Ifc_Test(ObjectJc* ithis, int32 input, ThCxt* _thCxt);
 

The method table is defined one time for all interface methods, containing both methods of this example of Java-interface:

 typedef struct Mtbl_Ifc_Test_t
 { MtblHeadJc head;
   MT_processIfcMethod_Ifc_Test* processIfcMethod;
   MT_anotherIfcmethod_i_Ifc_Test* anotherIfcmethod_i;
   MT_anotherIfcmethod_f_Ifc_Test* anotherIfcmethod_f;
   Mtbl_ObjectJc ObjectJc;
 } Mtbl_Ifc_Test;
 

An implementation uses this struct definition inside its more complex method table struct definition, defines a const method table instance and set the implementation of the method at the appropriate position, see ImplIfc.processIfcMethod(int).

Parameters:

input - Example

Returns:

Example

anotherIfcmethod

int anotherIfcmethod(int input)

Example for a second interface method, not a recentness, but see next anotherIfcmethod(float).

Parameters:

input -

Returns:

anotherIfcmethod

float anotherIfcmethod(float input)

Example for an interface method with same name as another in the same class, but other parameter set. The ambiguousness of the methods are detect and a unambiguous C-name is build. Therefore the two methods builds several method type declarations in headerfile:

 typedef int32 MT_anotherIfcmethod_i_Ifc_Test(ObjectJc* ithis, int32 input, ThCxt* _thCxt);
 typedef float MT_anotherIfcmethod_f_Ifc_Test(ObjectJc* ithis, float input, ThCxt* _thCxt);
 

and the adequate positions in the method table.

Parameters:

input -

Returns: