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public interface Environment
Defines an execution environment within which tasks can operate. The main job that it does is to be able to provide a String value for a given Parameter object. Every invocation of a Task is expected to have a new Environment.
Method Summary | |
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void |
acquireValue(Parameter par)
Obtains a legal value for a given parameter from the environment and sets the parameter's value accordingly. |
void |
clearValue(Parameter par)
Clears a value for a given parameter. |
PrintStream |
getErrorStream()
Returns an output stream into which error or logging output from a task can be written. |
String[] |
getNames()
Returns an array of parameter names which have been specified. |
PrintStream |
getOutputStream()
Returns an output stream into which text output from a task can be written. |
Method Detail |
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void acquireValue(Parameter par) throws TaskException
This environment should obtain a value for the parameter par
in whatever way it sees fit, and must then call par's
Parameter.setValueFromString(uk.ac.starlink.task.Environment, java.lang.String)
method so that the parameter
knows what its new value is. If the setValueFromString call
throws a ParameterValueException the environment may
try to get another value (for instance by re-prompting the user)
or may give up and re-throw the exception.
par
- the Parameter whose value is to be obtained and set
TaskException
void clearValue(Parameter par)
par
- the Parameter whose value is to be clearedString[] getNames()
PrintStream getOutputStream()
PrintStream getErrorStream()
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