Am 29.11.2011 20:23, schrieb Charles Oliver Nutter:
[...]
If you want to replace an incoming argument, you probably want to use
filterArguments like this:
// I always import static MethodHandles.* and MethodType.* to clean up code
MethodHandle handle =<get handle to System.setProperty>
// this line wraps a constant handle with a "drop", so it ignores the
String it is passed
MethodHandle replaceWithFoo = dropArguments(constant(String.class,
"foo"), 0, String.class);
// this line replaces the incoming property key with "foo", unconditionally
handle = filterArguments(handle, 0, replaceWithFoo);
arg... now I see... I always had the impression I have to use drop on
handle, but I forgot that it works actually reverse... well reverse to
what I would expect. Thanks, now it works in this variant.
Of course you can use a handle that actually processes the argument
and changes it into something else, like this version that upcases the
both strings on the way through:
MethodHandle upcase = lookup.findVirtual(String.class, "toUpperCase",
methodType(String.class);
handle = filterArguments(handle, 0, upcase, upcase);
That I managed. Only the version with the constant was missing.
It definitely takes a while to grok all the combinations of method
handle adapters, but once you get the hang of it you can do some
amazing things.
absolutely!
bye Jochen
--
Jochen "blackdrag" Theodorou - Groovy Project Tech Lead
blog: http://blackdragsview.blogspot.com/
german groovy discussion newsgroup: de.comp.lang.misc
For Groovy programming sources visit http://groovy-lang.org
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