Constructors/Destructors for struct with function pointers

[Takeshi]

I have code as ff:

typedef double* (*DBLPTRFUNCPTR )(int) ;
typedef int* (*INTPTRFUNCPTR )(int) ;
typedef double (*DBLFUNCPTR)(i nt) ;
typedef int (*INTFUNCPTR)(i nt) ;
etc ....


typedef struct
{
double *data;
int size;
int numcols;
int currcol;
DBLPTRFUNCPTR New ;
VOIDFUNCPTR Destroy ;
DBLFUNCPTR GetItem ;
VOIDFUNCPTR2 SetItem ;
} FArray, *FArrayPtr;


How can I pass a "this" ptr (i.e. ptr to the struct to my
allocate/dealllocate functions so I can write code like this (Yes I know
it is a "no-brainer in C++, but I have to implement this in Ansi C -
Basically, I'm porting C++ code using STL vectors, and I need this
functionality as a "wrapper")

/* Sample code*/

void foo( void ) {
double tmp ;
FArray array ;

array.New(10) /* Allocate a 1D array with 10 rows */
array.SetItem(1 )= 3.142 ;
tmp = array.GetItem(1 ) ;

array.Destroy() /* Free memory */
}


Many thanks in advance

[Jens.Toerring@physik.fu-berlin.de]

Re: Constructors/Destructors for struct with function pointers

Takeshi <do.not.spam.me @work.com> wrote:[color=blue]
> I have code as ff:[/color]
[color=blue]
> typedef double* (*DBLPTRFUNCPTR )(int) ;
> typedef int* (*INTPTRFUNCPTR )(int) ;
> typedef double (*DBLFUNCPTR)(i nt) ;
> typedef int (*INTFUNCPTR)(i nt) ;
> etc ....[/color]

[color=blue]
> typedef struct
> {
> double *data;
> int size;
> int numcols;
> int currcol;
> DBLPTRFUNCPTR New ;
> VOIDFUNCPTR Destroy ;
> DBLFUNCPTR GetItem ;
> VOIDFUNCPTR2 SetItem ;
> } FArray, *FArrayPtr;[/color]
[color=blue]
> How can I pass a "this" ptr (i.e. ptr to the struct to my
> allocate/dealllocate functions so I can write code like this (Yes I know
> it is a "no-brainer in C++, but I have to implement this in Ansi C -
> Basically, I'm porting C++ code using STL vectors, and I need this
> functionality as a "wrapper")[/color]
[color=blue]
> /* Sample code*/[/color]
[color=blue]
> void foo( void ) {
> double tmp ;
> FArray array ;[/color]
[color=blue]
> array.New(10) /* Allocate a 1D array with 10 rows */
> array.SetItem(1 )= 3.142 ;
> tmp = array.GetItem(1 ) ;[/color]
[color=blue]
> array.Destroy() /* Free memory */
> }[/color]

You must pass the address of the structure as another function argument
to your "class" functions yourself. I.e. make e.g
[color=blue]
> typedef double* ( *DBLPTRFUNCPTR )( FArrayPtr, int ) ;[/color]

and call it as

array.New( &array, 10 );

etc. There's no automatic passing of the structure to the array as
you might be used to from objects in C++.

Regards, Jens
--
\ Jens Thoms Toerring ___ Jens.Toerring@p hysik.fu-berlin.de
\______________ ____________ http://www.toerring.de

[CBFalconer]

Re: Constructors/Destructors for struct with function pointers

Jens.Toerring@p hysik.fu-berlin.de wrote:[color=blue]
> Takeshi <do.not.spam.me @work.com> wrote:
>[color=green]
>> I have code as ff:[/color]
>[color=green]
>> typedef double* (*DBLPTRFUNCPTR )(int) ;
>> typedef int* (*INTPTRFUNCPTR )(int) ;
>> typedef double (*DBLFUNCPTR)(i nt) ;
>> typedef int (*INTFUNCPTR)(i nt) ;
>> etc ....[/color]
>[color=green]
>> typedef struct
>> {
>> double *data;
>> int size;
>> int numcols;
>> int currcol;
>> DBLPTRFUNCPTR New ;
>> VOIDFUNCPTR Destroy ;
>> DBLFUNCPTR GetItem ;
>> VOIDFUNCPTR2 SetItem ;
>> } FArray, *FArrayPtr;[/color]
>[color=green]
>> How can I pass a "this" ptr (i.e. ptr to the struct to my
>> allocate/dealllocate functions so I can write code like this (Yes
>> I know it is a "no-brainer in C++, but I have to implement this
>> in Ansi C - Basically, I'm porting C++ code using STL vectors,
>> and I need this functionality as a "wrapper")[/color][/color]

Piggybacking on Jens posting, since the original has not appeared
here.

You might look at my recently released:

<http://cbfalconer.home .att.net/download/id2id-20.zip>

for a somewhat similar application. It is all in the interface to
the hashlib library, of which a complete but minimum instance is
included. If you back down to the download directory you will also
find the hashlib.zip, and other things.

I suggest you think in C, not in C++ for the coding. In the above
cases the hashtable is the object, into which other things can be
inserted, found, deleted, serialized, etc. In a wide variety of
cases those other objects are strings and auxiliary data, but they
can be anything.

--
Chuck F (cbfalconer@yah oo.com) (cbfalconer@wor ldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net> USE worldnet address!

[Takeshi]

Re: Constructors/Destructors for struct with function pointers

Many thanks - much appreciated

CBFalconer wrote:[color=blue]
> Jens.Toerring@p hysik.fu-berlin.de wrote:
>[color=green]
>>Takeshi <do.not.spam.me @work.com> wrote:
>>
>>[color=darkred]
>>>I have code as ff:[/color]
>>[color=darkred]
>>>typedef double* (*DBLPTRFUNCPTR )(int) ;
>>>typedef int* (*INTPTRFUNCPTR )(int) ;
>>>typedef double (*DBLFUNCPTR)(i nt) ;
>>>typedef int (*INTFUNCPTR)(i nt) ;
>>>etc ....[/color]
>>[color=darkred]
>>>typedef struct
>>>{
>>> double *data;
>>> int size;
>>> int numcols;
>>> int currcol;
>>> DBLPTRFUNCPTR New ;
>>> VOIDFUNCPTR Destroy ;
>>> DBLFUNCPTR GetItem ;
>>> VOIDFUNCPTR2 SetItem ;
>>>} FArray, *FArrayPtr;[/color]
>>[color=darkred]
>>>How can I pass a "this" ptr (i.e. ptr to the struct to my
>>>allocate/dealllocate functions so I can write code like this (Yes
>>>I know it is a "no-brainer in C++, but I have to implement this
>>>in Ansi C - Basically, I'm porting C++ code using STL vectors,
>>>and I need this functionality as a "wrapper")[/color][/color]
>
>
> Piggybacking on Jens posting, since the original has not appeared
> here.
>
> You might look at my recently released:
>
> <http://cbfalconer.home .att.net/download/id2id-20.zip>
>
> for a somewhat similar application. It is all in the interface to
> the hashlib library, of which a complete but minimum instance is
> included. If you back down to the download directory you will also
> find the hashlib.zip, and other things.
>
> I suggest you think in C, not in C++ for the coding. In the above
> cases the hashtable is the object, into which other things can be
> inserted, found, deleted, serialized, etc. In a wide variety of
> cases those other objects are strings and auxiliary data, but they
> can be anything.
>[/color]