Hi there,
I'm working on a code to read and write large amounts of binary data
according to a given specification. In the specification there are a lot
of "segments" defined. The segments in turn have defintions of datatypes
and what they represent, how many of some of the data values are present
in the file and sometimes the offset from the beginning of the file.
Now I wonder, what would be a good way to model the code.
Currently I have one class, that is the "FileReader". This class holds
the file object, information about the endianess and also a method to
read data (using the struct module). Then, I have more classes
representing the segements. In those classes I define data-formats, call
the read-method of the FileReader object and hold the data. Currently
I'm passing the FileReader object as arguement.
Here some examples, first the "FileReader" class:
class JTFile():
def __init__(self, file_obj):
self.file_stream = file_obj
self.version_string = ""
self.endian_format_prefix = ""
def read_data(self, fmt, pos = None):
format_size = struct.calcsize(fmt)
if pos is not None:
self.file_stream.seek(pos)
return struct.unpack_from(self.endian_format_prefix + fmt,
self.file_stream.read(format_size))
and here an example for a segment class that uses a FileReader instance
(file_stream):
class LSGSegement():
def __init__(self, file_stream):
self.file_stream = file_stream
self.lsg_root_element = None
self._read_lsg_root()
def _read_lsg_root(self):
fmt = "80Bi"
raw_data = self.file_stream.read_data(fmt)
self.lsg_root_element = LSGRootElement(raw_data[:79], raw_data[79])
So, now I wonder, what would be a good pythonic way to model the
FileReader class. Maybe use a global functions to avoid passing the
FileReader object around? Or something like "Singleton" I've heard about
but never used it? Or keept it like that?
Cheers,
Jan
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