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maybee November 23, 2013 10:06

Questions about several Class Descriptions
when reading the following OpenFoam class descriptions I am not able to understand all:

1.Time: Class to control time during OpenFOAM simulations that is also the top-level objectRegistry.
2.Clock:Read access to the system clock with formatting.
3.CpuTime:Starts timing CPU usage and return elapsed time from start.
4.TimePaths: A class for addressing time paths without using the Time class.
5.objectRegistry: Registry of regIOobjects.
6.regIOobjects:regIOobject is an abstract class derived from IOobject to handle automatic object registration with the objectRegistry.
7.IOobject: IOobject defines the attributes of an object for which implicit objectRegistry management is supported, and provides the infrastructure for performing stream I/O.

1.What means top-level objectRegistry?
2.what means with formatting?
3.Does "Starts timing CPU usage" mean the same as "Starts CPU usage"?
4.What is meant with "adressing time paths" and what is a "time path" in this context?
5.What is a ObjectRegistry class good for?
6.What is meant with "automatic object registration with the objectRegistry"?
7.What is meant with "objectRegistry management" ?
Hopefully some people with more programming knowledge will be able to teach me something here :) .


ngj November 24, 2013 13:14

Hi Maybee,

I will try to address some of your questions:

Ad. 1.: All objects such as volScalarField, surfaceVectorField, dictionaries, etc are registered in a database for easy access across the code. This is what is termed the object registry.

Ad. 3.: The time path is used to look up objects in the correct time folders when starting the simulations and for the model to know in which time folder output should be written.

Ad. 5.: See Ad. 1.

I do not have a clear answer on your other questions, as they seem to rely on some comment in a source code file, so I will not try to guess on the meaning of those.

Good luck,


wyldckat November 24, 2013 17:39

Greetings to all!

I hope that most of the questions regarding "objectRegistry" are answered here: (big thanks to Marupio:

More information is available from here:

Best regards,

maybee November 25, 2013 07:40

Hi, thanks for the answers. I am sure they are helpful. I'll check that all later.

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