Package ptolemy.actor.parameters

Class FilePortParameter

  • All Implemented Interfaces:
    java.lang.Cloneable, Initializable, HasTypeConstraints, Typeable, FileOrURLAccessor, Changeable, Debuggable, DebugListener, Derivable, HierarchyListener, ModelErrorHandler, MoMLExportable, Moveable, Nameable, Settable, ValueListener
    public class FilePortParameter
extends PortParameter
implements FileOrURLAccessor
    This file parameter creates an associated port that can be used to update the current value of the parameter. The value of this parameter, accessed by getExpression(), is a string that names a file or URL, possibly containing references to variables defined in scope using the syntax $ID, ${ID} or $(ID). The value returned by getToken() is name of the file with such references resolved.

    If the model containing this port parameter has been saved to a MoML file, then the file name can be given relative to the directory containing that MoML file. If the model has not been saved to a file, then the classpath is used for identifying relative file names.

    Files can be given relative to a base, where the base is the URI of the first container above this one that has a URIAttribute. Normally, this URI specifies the file or URL containing the model definition. Thus, files that are referred to here can be kept in the same directory as the model, or in a related directory, and can moved together with the model.

    The following special file names are understood:

    • System.in: Standard input.
    • System.out: Standard output.
    Note, however, that these file names cannot be converted to URLs using the asURL() method. A file name can also contain the following strings that start with "$", which get substituted with the appropriate values.
    Variables that get substituted.
    String Description Property
    $CWD The current working directory user.dir
    $HOME The user's home directory user.home
    $PTII The home directory of the Ptolemy II installation ptolemy.ptII.dir
    $TMPDIR The temporary directory java.io.tmpdir
    $USERNAME The user's account name user.name
    The above properties are normally set when a Ptolemy II application starts.

    If a file name begins with the reference "$CLASSPATH", then when the file is opened for reading, the openForReading() method will search for the file relative to the classpath (using the getResource() method of the current class loader). This will only work for a file that exists, and thus the openForWriting() method will not understand the "$CLASSPATH" string; this makes sense since the classpath typically has several directories, and it would not be obvious where to create the file. The asURL() method also recognizes the "$CLASSPATH" string, but not the asFile() method (which is typically used when accessing a file for writing). NOTE: If the container of this parameter also contains a variable named CLASSPATH, then the value of that variable is used instead of the Java classpath.

    This parameter has two values, which may not be equal, a current value and a persistent value. The persistent value is returned by getExpression() and is set by any of three different mechanisms:

    • calling setExpression();
    • calling setToken(); and
    • specifying a value as a constructor argument.
    All three of these will also set the current value, which is then equal to the persistent value. The current value is returned by get getToken() and is set by any of three different mechanisms:
    • calling setCurrentValue();
    • calling update() sets the current value if there is an associated port, and that port has a token to consume; and
    These three techniques do not change the persistent value, so after these are used, the persistent value and current value may be different.

    When using this parameter in an actor, care must be exercised to call update() exactly once per firing prior to calling getToken(). Each time update() is called, a new token will be consumed from the associated port (if the port is connected and has a token). If this is called multiple times in an iteration, it may result in consuming tokens that were intended for subsequent iterations. Thus, for example, update() should not be called in fire() and then again in postfire(). Moreover, in some domains (such as DE), it is essential that if a token is provided on a port, that it is consumed. In DE, the actor will be repeatedly fired until the token is consumed. Thus, it is an error to not call update() once per iteration. For an example of an actor that uses this mechanism, see Ramp.

    If this actor is placed in a container that does not implement the TypedActor interface, then no associated port is created, and it functions as an ordinary file parameter. This is useful, for example, if this is put in a library, where one would not want the associated port to appear.

    There are a few situations where FilePortParameter might not do what you expect:

    1. If it is used in a transparent composite actor, then a token provided to a FilePortParameter will never be read. A transparent composite actor is one without a director.
      Workaround: Put a director in the composite.
    2. Certain actors read parameter values only during initialization. During initialization, a FilePortParameter can only have a value set via the parameter (it can't have yet received a token). So if the initial value is set to the value of the FilePortParameter, then it will see only the parameter value, never the value provided via the port.
      Workaround: Use a RunCompositeActor to contain the model.
    Since:
    Ptolemy II 4.1
    Version:
    $Id$
    Author:
    Edward A. Lee
    See Also:
    FileParameter, ParameterPort
    Pt.AcceptedRating:
    Red (cxh)
    Pt.ProposedRating:
    Yellow (eal)

    • Constructor Detail

      • FilePortParameter

        public FilePortParameter​(NamedObj container,
                         java.lang.String name)
                  throws IllegalActionException,
                         NameDuplicationException
        Construct a parameter with the given name contained by the specified entity. The container argument must not be null, or a NullPointerException will be thrown. This parameter will create an associated port in the same container.
        Parameters:
        container - The container.
        name - The name of the parameter.
        Throws:
        IllegalActionException - If the parameter is not of an acceptable class for the container.
        NameDuplicationException - If the name coincides with a parameter already in the container.

      • FilePortParameter

        public FilePortParameter​(NamedObj container,
                         java.lang.String name,
                         Token token)
                  throws IllegalActionException,
                         NameDuplicationException
        Construct a Parameter with the given container, name, and Token. The token defines the initial persistent and current values. The container argument must not be null, or a NullPointerException will be thrown. This parameter will use the workspace of the container for synchronization and version counts. If the name argument is null, then the name is set to the empty string. The object is not added to the list of objects in the workspace unless the container is null. Increment the version of the workspace. If the name argument is null, then the name is set to the empty string.
        Parameters:
        container - The container.
        name - The name.
        token - The Token contained by this Parameter.
        Throws:
        IllegalActionException - If the parameter is not of an acceptable class for the container.
        NameDuplicationException - If the name coincides with an parameter already in the container.

    • Method Detail

      • asFile

        public java.io.File asFile()
                    throws IllegalActionException
        Return the file as a File object. This method first attempts to directly use the file name to construct the File. If the resulting File is not absolute, then it attempts to resolve it relative to the base directory returned by getBaseDirectory(). If there is no such base URI, then it simply returns the relative File object.

        The file need not exist for this method to succeed. Thus, this method can be used to determine whether a file with a given name exists, prior to calling openForWriting(). A typical usage looks like this: 

              FileParameter fileParameter;
      ...
      File file = fileParameter.asFile();
      if (file.exists()) {
         ... Ask the user if it's OK to overwrite...
         ... Throw an exception if not...
      }
      // The following will overwrite an existing file.
      Writer writer = new PrintWriter(fileParameter.openForWriting());
        Specified by:
        asFile in interface FileOrURLAccessor
        Returns:
        A File, or null if no file name has been specified.
        Throws:
        IllegalActionException - If a parse error occurs reading the file name.
        See Also:
        getBaseDirectory()

      • asURL

        public java.net.URL asURL()
                   throws IllegalActionException
        Return the file as a URL. If the file name is relative, then it is interpreted as being relative to the directory returned by getBaseDirectory(). If the name begins with "$CLASSPATH", then search for the file relative to the classpath. If no file is found, then it throws an exception.
        Specified by:
        asURL in interface FileOrURLAccessor
        Returns:
        A URL, or null if no file name or URL has been specified.
        Throws:
        IllegalActionException - If the file cannot be read, or if the file cannot be represented as a URL (e.g. System.in), or the name specification cannot be parsed.

      • clone

        public java.lang.Object clone​(Workspace workspace)
                       throws java.lang.CloneNotSupportedException
        Clone the attribute into the specified workspace. The resulting object has no base directory name nor any reference to any open stream.
        Overrides:
        clone in class PortParameter
        Parameters:
        workspace - The workspace for the cloned object.
        Returns:
        A new attribute.
        Throws:
        java.lang.CloneNotSupportedException - If a derived class contains an attribute that cannot be cloned.
        See Also:
        Object.clone()

      • close

        public void close()
           throws IllegalActionException
        Close the file. If it has not been opened using openForReading() or openForWriting(), then do nothing. Also, if the file is System.in or System.out, then do not close it (it does not make sense to close these files).
        Specified by:
        close in interface FileOrURLAccessor
        Throws:
        IllegalActionException - If the file or URL cannot be closed.

      • getBaseDirectory

        public java.net.URI getBaseDirectory()
        Return the directory to use as the base for relative file or URL names. If setBaseDirectory() has been called, then that directory is returned. Otherwise, the directory containing the file returned by URIAttribute.getModelURI() is returned, which is the URI of the first container above this attribute in the hierarchy that has a URIAttribute, or null if there none.
        Specified by:
        getBaseDirectory in interface FileOrURLAccessor
        Returns:
        A directory name, or null if there is none.
        See Also:
        URIAttribute.getModelURI(NamedObj), setBaseDirectory(URI)

      • openForReading

        public java.io.BufferedReader openForReading()
                                      throws IllegalActionException
        Open the file or URL for reading. If the name begins with "$CLASSPATH", then search for the file relative to the classpath. If the name is relative, then it is relative to the directory returned by getBaseDirectory().
        Specified by:
        openForReading in interface FileOrURLAccessor
        Returns:
        A buffered reader.
        Throws:
        IllegalActionException - If the file or URL cannot be opened.
        See Also:
        getBaseDirectory()

      • openForWriting

        public java.io.Writer openForWriting()
                              throws IllegalActionException
        Open the file for writing. If the file does not exist, then create it. If the file name is not absolute, the it is assumed to be relative to the base directory returned by getBaseDirectory(). If permitted, this method will return a Writer that will simply overwrite the contents of the file. It is up to the user of this method to check whether this is OK (by first calling asFile() and calling exists() on the returned value).
        Specified by:
        openForWriting in interface FileOrURLAccessor
        Returns:
        A writer, or null if no file name has been specified.
        Throws:
        IllegalActionException - If the file cannot be opened or created.
        See Also:
        getBaseDirectory(), asFile()

      • openForWriting

        public java.io.Writer openForWriting​(boolean append)
                              throws IllegalActionException
        Open the file for writing or appending. If the file does not exist, then create it. If the file name is not absolute, the it is assumed to be relative to the base directory returned by getBaseDirectory(). If permitted, this method will return a Writer that will simply overwrite the contents of the file. It is up to the user of this method to check whether this is OK (by first calling asFile() and calling exists() on the returned value).
        Specified by:
        openForWriting in interface FileOrURLAccessor
        Parameters:
        append - If true, then append to the file rather than overwriting.
        Returns:
        A writer, or null if no file name has been specified.
        Throws:
        IllegalActionException - If the file cannot be opened or created.
        See Also:
        getBaseDirectory(), asFile()

      • setBaseDirectory

        public void setBaseDirectory​(java.net.URI directory)
        Set the directory to use as the base for relative file or URL names. If this is not called, then the default is the directory containing the file returned by URIAttribute.getModelURI().
        Specified by:
        setBaseDirectory in interface FileOrURLAccessor
        Parameters:
        directory - The base directory.
        See Also:
        URIAttribute.getModelURI(NamedObj), getBaseDirectory()

      • stringValue

        public java.lang.String stringValue()
                             throws IllegalActionException
        Return the string value of this parameter. This is equivalent to 
             ((StringToken)this.getToken()).stringValue()
        Returns:
        The string value of this parameter.
        Throws:
        IllegalActionException - If the expression cannot be parsed or cannot be evaluated, or if the result of evaluation violates type constraints, or if the result of evaluation is null and there are variables that depend on this one.