VLBIHeaderBase

class baseband.vlbi_base.header.VLBIHeaderBase(words, verify=True)

Bases: object

Base class for all VLBI headers.

Defines a number of common routines.

Generally, the actual class should define:

_struct: Struct instance that can pack/unpack header words.

_header_parser: HeaderParser instance corresponding to this class.

_properties: tuple of properties accessible/usable in initialisation

It also should define properties (getters and setters):

payload_nbytes: number of bytes used by payload

frame_nbytes: total number of bytes for header + payload

get_time, set_time, and a corresponding time property:

time at start of payload

Parameters:

words : tuple or list of int, or None

header words (generally, 32 bit unsigned int). If None, set to a list of zeros for later initialisation. If given as a tuple, the header is immutable.

verify : bool

Whether to do basic verification of integrity. For the base class, checks that the number of words is consistent with the struct size.

Attributes Summary

mutable	Whether the header can be modified.
nbytes	Size of the header in bytes.

Methods Summary

copy(**kwargs)	Create a mutable and independent copy of the header.
fromfile(fh, *args, **kwargs)	Read VLBI Header from file.
fromkeys(*args, **kwargs)	Initialise a header from parsed values.
fromvalues(*args, **kwargs)	Initialise a header from parsed values.
keys()
tofile(fh)	Write VLBI frame header to filehandle.
update(**kwargs)	Update the header by setting keywords or properties.
verify()	Verify that the length of the words is consistent.

Attributes Documentation

mutable

Whether the header can be modified.

nbytes

Size of the header in bytes.

Methods Documentation

copy(**kwargs)

Create a mutable and independent copy of the header.

Keyword arguments can be passed on as needed by possible subclasses.

classmethod fromfile(fh, *args, **kwargs)

Read VLBI Header from file.

Arguments are the same as for class initialisation. The header constructed will be immutable.

classmethod fromkeys(*args, **kwargs)

Initialise a header from parsed values.

Like fromvalues, but without any interpretation of keywords.

Raises:KeyError : if not all keys required are present in kwargs

classmethod fromvalues(*args, **kwargs)

Initialise a header from parsed values.

Here, the parsed values must be given as keyword arguments, i.e., for any header = cls(<words>), cls.fromvalues(**header) == header.

However, unlike for the fromkeys class method, data can also be set using arguments named after header methods, such as time.

Parameters:

*args

Possible arguments required to initialize an empty header.

**kwargs

Values used to initialize header keys or methods.

keys()

tofile(fh)

Write VLBI frame header to filehandle.

update(**kwargs)

Update the header by setting keywords or properties.

Here, any keywords matching header keys are applied first, and any remaining ones are used to set header properties, in the order set by the class (in _properties).

Parameters:

verify : bool, optional

If True (default), verify integrity after updating.

**kwargs

Arguments used to set keywords and properties.

verify()

Verify that the length of the words is consistent.

Subclasses should override this to do more thorough checks.