lsst.pipe.base  19.0.0-22-g8325f40
Public Member Functions | List of all members
lsst.pipe.base.struct.Struct Class Reference

Public Member Functions

def __init__ (self, **keyArgs)
 
def getDict (self)
 
def mergeItems (self, struct, *nameList)
 
def copy (self)
 
def __eq__ (self, other)
 
def __len__ (self)
 
def __repr__ (self)
 

Detailed Description

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.

Constructor & Destructor Documentation

◆ __init__()

def lsst.pipe.base.struct.Struct.__init__ (   self,
**  keyArgs 
)

Definition at line 61 of file struct.py.

Member Function Documentation

◆ __eq__()

def lsst.pipe.base.struct.Struct.__eq__ (   self,
  other 
)

Definition at line 133 of file struct.py.

◆ __len__()

def lsst.pipe.base.struct.Struct.__len__ (   self)

Definition at line 136 of file struct.py.

◆ __repr__()

def lsst.pipe.base.struct.Struct.__repr__ (   self)

Definition at line 139 of file struct.py.

◆ copy()

def lsst.pipe.base.struct.Struct.copy (   self)
Make a one-level-deep copy (values are not copied).

Returns
-------
copy : `Struct`
    One-level-deep copy of this Struct.

Definition at line 123 of file struct.py.

◆ getDict()

def lsst.pipe.base.struct.Struct.getDict (   self)
Get a dictionary of fields in this struct.

Returns
-------
structDict : `dict`
    Dictionary with field names as keys and field values as values. The values are shallow copies.

Definition at line 86 of file struct.py.

◆ mergeItems()

def lsst.pipe.base.struct.Struct.mergeItems (   self,
  struct,
nameList 
)
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 96 of file struct.py.


The documentation for this class was generated from the following file: