我一直用書實用的Ruby寶石。它給了我下面的代碼,我寫了:未定義的方法,MIDI
require 'dl/import'
class LiveMIDI
ON = 0x90
OFF = 0x80
PC = 0xC0
def initialize
open
end
def noteon(channel, note, velocity=64)
message(ON | channel, note, velocity)
end
def noteoff(channel, note, velocity=64)
message(OFF | channel, note, velocity)
end
def programchange(channel, preset)
message(PC | channel, preset)
end
module C
extend DL::Importer
dlload '/System/Library/Frameworks/CoreMIDI.framework/Versions/Current/CoreMIDI'
extern "int MIDIClientCreate(void *, void *, void *, void *)"
extern "int MIDIClientDispose(void *)"
extern "int MIDIGetNumberOfDestinations()"
extern "void * MIDIGetDestination(int)"
extern "int MIDIOutputPortCreate(void *, void *, void *)"
extern "void * MIDIPacketListInit(void *)"
extern "void * MIDIPacketListAdd(void *, int, void *, int, int, int, void *)"
extern "int MIDISend(void *, void *, void *)"
end
module CF
extend DL::Importer
dlload '/System/Library/Frameworks/CoreFoundation.framework/Versions/Current/CoreFoundation'
extern "void * CFStringCreateWithCString (void *, char *, int)"
end
def open
client_name = CF.CFStringCreateWithCString(nil, "RubyMIDI", 0)
@client = DL::PtrData.new(nil)
C.mIDIClientCreate(client_name, nil, nil, @client.ref);
port_name = CF.cFStringCreateWithCString(nil, "Output", 0)
@outport = DL::PtrData.new(nil)
C.mIDIOutputPortCreate(@client, port_name, @outport.ref);
num = C.mIDIGetNumberOfDestinations()
raise NoMIDIDestinations if num < 1
@destination = C.mIDIGetDestination(0)
end
def close
C.mIDIClientDispose(@client)
end
def message(*args)
format = "C" * args.size
bytes = args.pack(format).to_ptr
packet_list = DL.malloc(256)
packet_ptr = C.mIDIPacketListInit(packet_list)
# Pass in two 32 bit 0s for the 64 bit time
packet_ptr = C.mIDIPacketListAdd(packet_list, 256, packet_ptr, 0, 0, args.size, bytes)
C.mIDISend(@outport, @destination, packet_list)
end
end
當我嘗試運行它,我得到以下錯誤,我不明白,我從來沒有與DL:
工作過livemidi.rb:36:in `open': undefined method `cFStringCreateWithCString' for LiveMIDI::CF:Module (NoMethodError)
from livemidi.rb:7:in `initialize'
from livemidi.rb:63:in `new'
from livemidi.rb:63:in `<main>'
這是爲什麼??? 我正在使用Ruby 1.9.3,在Mac OS X上 你能幫我修復這個bug嗎?
應該是顯而易見的,不存在所謂的'CFStringCreateWithCString'方法。 – 2012-05-02 23:34:34