How to create my own functionObject ?
 

Dear all,
I use functionObjedt like following:
functions
{
extraction
{
type surfaces;
functionObjectLibs ("libsampling.so");
enabled true;
outputControl timeStep;
outputInterval 5;
surfaceFormat foamFile;
interpolationScheme cellPointFace;
fields
(
U
T
);
surfaces
(
aplane
{
type plane;
basePoint (-0.4 0 0.5);
normalVector (1.0 0 0);
}
);
}
}

my purpose is to extract a plane data of internal domain in every time step. But the file directory is not what I want.
I copy src/sampling ,and modify a little ,create another called libmysampling.so.

but when using, it displays:

--> FOAM Warning :
From function dlLibraryTable::open(const dictionary& dict, const word& libsEntry, const TablePtr tablePtr)
in file lnInclude/dlLibraryTableTemplates.C at line 68
library "libmysampling.so" did not introduce any new entries

It seems that my own libmysampling.so doesn't take effect.
Could any one tell me how to create functionObject type ?
Thanks.

I want to modify surfaces functionObject, I found it belongs to sampling,
So I copy src/sampling directory to another position.
I changed the name to LIB = $(FOAM_USER_LIBBIN)/libmysampling.

in sampling\sampledSurface\sampledSurfaces, I found 2 places had name "surfaces",

*.H file:
public:
//- Runtime type information
TypeName("surfaces");
*.C文file：
PtrList<sampledSurface> newList
(
dict.lookup("surfaces"),
sampledSurface::iNew(mesh_)
);

I changed these "surfaces" to "mysurfaces", and compiled, no problem.
but when I used, had the following mistake,

Starting time loop
--> FOAM Warning :
From function dlLibraryTable::open(const dictionary& dict, const word& libsEntry, const TablePtr tablePtr)
in file lnInclude/dlLibraryTableTemplates.C at line 68
library "libmysampling.so" did not introduce any new entries

Unknown function type mysurfaces
Valid functions are :
5
(
surfaces
fieldAverage
fieldMinMax
sets
probes
)

From function functionObject::New(const word& name, const Time&, const dictionary&)
in file db/functionObjects/functionObject/functionObject.C at line 89.
FOAM exiting

It seems that my modified name haven't been registed in functionObject.
Could anyone can give me some help ?

Thanks.

I am using like this in my controlDict file:
extraction
{
type mysurfaces;
functionObjectLibs ("libmysampling.so");
enabled true;
outputControl timeStep;
outputInterval 1;
surfaceFormat foamFile;
interpolationScheme cellPointFace;
fields
(
U
T
);
mysurfaces
(
aplane
{
type plane;
basePoint (-0.4 0 0.5);
normalVector (1.0 0 0);
}
);
}

Not able to use newly created library
 

I have created a library successfully, but I am not able to use it, It is giving error like below. Any help or input would be greatly appreciated..

Type of Error

--> FOAM Warning :
From function dlLibraryTable::open(const dictionary& dict, const word& libsEntry, const TablePtr tablePtr)
in file lnInclude/dlLibraryTableTemplates.C at line 68
library "monitor.so" did not introduce any new entries



Unknown function type monitor

Table of functionObjects is empty

From function functionObject::New(const word& functionType, const Time&, const dictionary&)
in file db/functionObject/functionObject.C at line 75.

FOAM exiting

functionObject in ControlDict

functions
(
monitor
{
type monitor;
functionObjectLibs ("monitor.so");
inletPatches (VolImp);
outletPatches (Outflow);
rhoInf 998.0;
}
);

My Inputs/Findings/Observations

I searched over OpenFOAM forums, there were few discussion regarding this, which say if OpenFOAM-1.6 is being used then it might causing because some parameters in functionobject are missing in controlDict file. It also says error messages displayed for this problem in OpenFOAM-1.6 and OpenFOAM-1.5 are different, OpenFOAM-1.6 says as above but OpenFOAM-1.5 says "parameters are missing". Since I am using OpenFOAM-1.5 there must be another reason for this error..

If you try with
it might work for you.
Note the 'lib' prefix when specifying the library to load.

Actually, it could be a good RFE to automatically add the 'lib' prefix and the '.so' suffix.
I just don't know how this might look on other systems though.

Thank you Olesen for suggestion..
According to your suggestion, I created a new library called libmonitor.so and loaded it in controlDict by using functionObjectLibs ("libmonitor.so"); but it is giving the same error with new library name. Below is error produced by simpleFoam. Please note when I changed functionObjectLibs ("monitor.so"); to functionObjectLibs ("libmonitor.so"); in controlDict then OpenFOAM asked for missing library so I created by name of libmonitor.so instead of monitor.so

What would you suggest in this case, should I debug simpleFoam code ??? I do not know what help I could get by debuging but since I am a software engineer I know this way only.

Type of Error
Starting time loop

--> FOAM Warning :
From function dlLibraryTable::open(const dictionary& dict, const word& libsEntry, const TablePtr tablePtr)
in file lnInclude/dlLibraryTableTemplates.C at line 68
library "libmonitor.so" did not introduce any new entries



Unknown function type monitor

Table of functionObjects is empty

From function functionObject::New(const word& functionType, const Time&, const dictionary&)
in file db/functionObject/functionObject.C at line 75.

FOAM exiting

I finally managed to create a library which works well.

Solution of the problem :

updateMesh(const mapPolyMesh&)

movePoints(const pointField&)

Above virtual functions have to be overridden and FuctionObjects header file and C files need to be included.