uk.ac.starlink.task
Class TerminalEnvironment

java.lang.Object
  extended by uk.ac.starlink.task.TerminalEnvironment
All Implemented Interfaces:
Environment

public class TerminalEnvironment
extends Object
implements Environment

Implementation of Environment which accepts an initial command line, and communicates with the user using standard input and standard output.

This environment is somewhat deprecated in favour of the more capable LineEnvironment.

Author:
Mark Taylor (Starlink)

Field Summary
static int NUM_TRIES
          The number of goes you get to put in an invalid parameter.
 
Constructor Summary
TerminalEnvironment(String[] args, Parameter[] params)
          Constructs a new Environment based on a String array containing supplied arguments, and a list of parameters which may be encountered.
 
Method Summary
 void acquireValue(Parameter par)
          Sets the value of a parameter.
 void clear(Parameter par)
           
 void clearValue(Parameter par)
          Clears a value for a given parameter.
 PrintStream getErrorStream()
          Returns System.err.
 String[] getNames()
          Returns an array of parameter names which have been specified.
 PrintStream getOutputStream()
          Returns System.out.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

NUM_TRIES

public static int NUM_TRIES
The number of goes you get to put in an invalid parameter.

Constructor Detail

TerminalEnvironment

public TerminalEnvironment(String[] args,
                           Parameter[] params)
                    throws UsageException
Constructs a new Environment based on a String array containing supplied arguments, and a list of parameters which may be encountered. The initial arguments may have the form value or name=value; in the former case they must correspond to a parameter with a non-zero position attribute indicating where it is expected on the command line, and in the latter case the name must correspond to the name of one of the parameters in params.

Parameters:
args - an array of words found on the command line
params - an array of Parameter objects which this Environment may be asked to get values for
Throws:
UsageException
Method Detail

clear

public void clear(Parameter par)

acquireValue

public void acquireValue(Parameter par)
                  throws TaskException
Sets the value of a parameter. If it a value has been specified on the command line then that is used, otherwise any known default is used, otherwise the user is prompted on standard output and response got from standard input.

A more configurable order (cf ADAM PPATH/VPATH) could be implemented by adding some methods to Parameter and getting this method to query them.

Specified by:
acquireValue in interface Environment
Parameters:
par - the parameter whose value is to be set
Throws:
TaskException

clearValue

public void clearValue(Parameter par)
Description copied from interface: Environment
Clears a value for a given parameter.

Specified by:
clearValue in interface Environment
Parameters:
par - the Parameter whose value is to be cleared

getNames

public String[] getNames()
Description copied from interface: Environment
Returns an array of parameter names which have been specified. The result is not necessarily an exhaustive list of all parameters whose values can be retrieved from this environment, since an interactive environment may be able to prompt the user for values, but it can give a list of values provided explicitly or without interactive prompts.

Specified by:
getNames in interface Environment
Returns:
array of names of known supplied parameters

getOutputStream

public PrintStream getOutputStream()
Returns System.out.

Specified by:
getOutputStream in interface Environment
Returns:
System.out

getErrorStream

public PrintStream getErrorStream()
Returns System.err.

Specified by:
getErrorStream in interface Environment
Returns:
System.err


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