A container to which you can add fields as attributes.
Parameters
----------
keyArgs
keyword arguments specifying fields and their values.
Notes
-----
Intended to be used for the return value from `~lsst.pipe.base.Task.run`
and other `~lsst.pipe.base.Task` methods, and useful for any method that
returns multiple values.
The intent is to allow accessing returned items by name, instead of
unpacking a tuple. This makes the code much more robust and easier to
read. It allows one to change what values are returned without inducing
mysterious failures: adding items is completely safe, and removing or
renaming items causes errors that are caught quickly and reported in a way
that is easy to understand.
The primary reason for using Struct instead of dict is that the fields may
be accessed as attributes, e.g. ``aStruct.foo`` instead of
``aDict["foo"]``. Admittedly this only saves a few characters, but it
makes the code significantly more readable.
Struct is preferred over named tuples, because named tuples can be used as
ordinary tuples, thus losing all the safety advantages of Struct. In
addition, named tuples are clumsy to define and Structs are much more
mutable (e.g. one can trivially combine Structs and add additional fields).
Examples
--------
>>> myStruct = Struct(
>>> strVal = 'the value of the field named "strVal"',
>>> intVal = 35,
>>> )
Definition at line 26 of file struct.py.
def lsst.pipe.base.struct.Struct.mergeItems |
( |
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self, |
|
|
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struct, |
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* |
nameList |
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) |
| |
Copy specified fields from another struct, provided they don't
already exist.
Parameters
----------
struct : `Struct`
`Struct` from which to copy.
*nameList : `str`
All remaining arguments are names of items to copy.
Raises
------
RuntimeError
Raised if any item in nameList already exists in self (but any
items before the conflicting item in nameList will have been
copied).
Examples
--------
For example::
foo.copyItems(other, "itemName1", "itemName2")
copies ``other.itemName1`` and ``other.itemName2`` into self.
Definition at line 104 of file struct.py.