Difference between revisions of "OpenFOAM guide/Input and Output operations using dictionaries and the IOobject class"
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Many input/output operations are performed in OpenFOAM using the IOobject class, which is described in its header file as follows: | Many input/output operations are performed in OpenFOAM using the IOobject class, which is described in its header file as follows: | ||
''IOobject defines the attributes of an object for which implicit objectRegistry management is supported, and provides the infrastructure for performing stream I/O. An IOobject is constructed with an object name, a class name, an instance path, a reference to a objectRegistry, and parameters determining its storage status.'' | ''IOobject defines the attributes of an object for which implicit objectRegistry management is supported, and provides the infrastructure for performing stream I/O. An IOobject is constructed with an object name, a class name, an instance path, a reference to a objectRegistry, and parameters determining its storage status.'' | ||
| − | + | == IOobject constructors == | |
The constructor of an IOobject may have two forms: | The constructor of an IOobject may have two forms: | ||
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While reading the two previous code snippets, remember that string inherits word, from which fileName is derived. Moreover, both Time and polyMesh inherit objectRegistry. As a consequence fvMesh, inheriting polyMesh, indirectly inherits objectRegistry too. For further information, see the [http://foam.sourceforge.net/doc/Doxygen/html/da/df5/classFoam_1_1IOobject.html IOobject class reference]. | While reading the two previous code snippets, remember that string inherits word, from which fileName is derived. Moreover, both Time and polyMesh inherit objectRegistry. As a consequence fvMesh, inheriting polyMesh, indirectly inherits objectRegistry too. For further information, see the [http://foam.sourceforge.net/doc/Doxygen/html/da/df5/classFoam_1_1IOobject.html IOobject class reference]. | ||
| − | + | == Read options == | |
Read options, which define what is done on object construction and explicit reads, are: | Read options, which define what is done on object construction and explicit reads, are: | ||
* MUST_READ | * MUST_READ | ||
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Don't read the object. | Don't read the object. | ||
| − | + | == Write options == | |
Write options, which define what is done on object destruction and explicit writes, are: | Write options, which define what is done on object destruction and explicit writes, are: | ||
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The object is not written automatically on destruction, but it can be written explicitly. | The object is not written automatically on destruction, but it can be written explicitly. | ||
| − | + | == IOobject and dictionaries == | |
Dictionaries can be read using the IOobject class when they are declared. Usually the readOption for a dictionary is MUST_READ, while the writeOption is NO_WRITE not to overwrite the settings contained in the dictionary. | Dictionaries can be read using the IOobject class when they are declared. Usually the readOption for a dictionary is MUST_READ, while the writeOption is NO_WRITE not to overwrite the settings contained in the dictionary. | ||
For example, for the usual transportProperties dictionary, the syntax is: | For example, for the usual transportProperties dictionary, the syntax is: | ||
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where runTime.constant() gives the position of the dictionary, which is, in this case, contained in the constant directory of the considered case. | where runTime.constant() gives the position of the dictionary, which is, in this case, contained in the constant directory of the considered case. | ||
| − | + | == IOobect and fields == | |
Input/output options for a field can be set similarly to | Input/output options for a field can be set similarly to | ||
Revision as of 01:27, 13 August 2005
Many input/output operations are performed in OpenFOAM using the IOobject class, which is described in its header file as follows:
IOobject defines the attributes of an object for which implicit objectRegistry management is supported, and provides the infrastructure for performing stream I/O. An IOobject is constructed with an object name, a class name, an instance path, a reference to a objectRegistry, and parameters determining its storage status.
Contents
1 IOobject constructors
The constructor of an IOobject may have two forms:
- Construct from name, instance, registry and IO options
IOobject ( const word & name, const word & instance, const objectRegistry & registry, readOption r = NO_READ, writeOption w = NO_WRITE, bool registerObject = true )
- Construct from name, instance, local, registry and IO options
IOobject ( const word & name, const word & instance, const fileName & local, const objectRegistry & registry, readOption r = NO_READ, writeOption w = NO_WRITE, bool registerObject = true )
While reading the two previous code snippets, remember that string inherits word, from which fileName is derived. Moreover, both Time and polyMesh inherit objectRegistry. As a consequence fvMesh, inheriting polyMesh, indirectly inherits objectRegistry too. For further information, see the IOobject class reference.
2 Read options
Read options, which define what is done on object construction and explicit reads, are:
- MUST_READ
The object must be read from Istream on construction. An error message is produced if Istream does not exist or can't be read.
- READ_IF_PRESENT
It reads the object from Istream if Istream exists, otherwise doesn't. An error message is produced only if Istream exists but can't be read.
- NO_READ
Don't read the object.
3 Write options
Write options, which define what is done on object destruction and explicit writes, are:
- AUTO_WRITE
The object is written automatically when requested to by the objectRegistry.
- NO_WRITE
The object is not written automatically on destruction, but it can be written explicitly.
4 IOobject and dictionaries
Dictionaries can be read using the IOobject class when they are declared. Usually the readOption for a dictionary is MUST_READ, while the writeOption is NO_WRITE not to overwrite the settings contained in the dictionary. For example, for the usual transportProperties dictionary, the syntax is:
IOdictionary transportProperties ( IOobject ( "transportProperties", runTime.constant(), mesh, IOobject::MUST_READ, IOobject::NO_WRITE ) );
where runTime.constant() gives the position of the dictionary, which is, in this case, contained in the constant directory of the considered case.
5 IOobect and fields
Input/output options for a field can be set similarly to
