In a FLAC (as in Free Lossless Audio Codec) package for version 0.4 I used
@enum to create a type to pass to calls to the C library libflac.
"""
Metadata for a flac stream object.
Used in both encoding and decoding of a stream.
Each type of metadata object contains an indicator
of its `typ`, an indicator of whether this is the
last metadata block and its length, in bytes.
"""
abstract StreamMetaData
@enum(MetadataType,
InfoType=UInt32(0),
PaddingType,
ApplicationType,
SeektableType,
VorbisCommentType,
CueSheetType,
PictureType)
Some of the constructors are boilerplate, differing only in the
MetadataType. Can I iterate over these values and create all the
constructors in a macro call? Alternatively, if I iterate over the range
0:6, can I convert the integer to a MetadataType?
The boilerplate looks like
"""
A block containing information on the stream including
`samplerate`, `channels`, `bitspersample`, `totalsamples`,
and `mdsum`.
"""
type StreamInfoMetaData <: StreamMetaData
typ::MetadataType
is_last::Cint
len::Int64
minblocksize::Int32
maxblocksize::Int32
minframesize::Int32
maxframesize::Int32
samplerate::Int32
channels::Int32
bitspersample::Int32
totalsamples::Int64
md5sum::NTuple{16,UInt8}
end
"""
The zero-argument constructor uses storage allocated by libflac.
"""
function StreamInfoMetaData()
md = unsafe_load(ccall((:FLAC__metadata_object_new,libflac),
Ptr{StreamInfoMetaData},(MetadataType,),InfoType))
finalizer(md,x->ccall((:FLAC__metadata_object_delete,libflac),
Void,(Ptr{StreamInfoMetaData},),pointer(x)))
md
end
