22 from __future__
import absolute_import, division
24 from builtins
import object
30 """!A struct to which you can add any fields
32 Intended to be used for the return value from Task.run and other Task methods,
33 and useful for any method that returns multiple values.
35 The intent is to allow accessing returned items by name, instead of unpacking a tuple.
36 This makes the code much more robust and easier to read. It allows one to change what values are returned
37 without inducing mysterious failures: adding items is completely safe, and removing or renaming items
38 causes errors that are caught quickly and reported in a way that is easy to understand.
40 The primary reason for using Struct instead of dict is that the fields may be accessed as attributes,
41 e.g. aStruct.foo instead of aDict["foo"]. Admittedly this only saves a few characters, but it makes
42 the code significantly more readable.
44 Struct is preferred over named tuples, because named tuples can be used as ordinary tuples, thus losing
45 all the safety advantages of Struct. In addition, named tuples are clumsy to define and Structs
46 are much more mutable (e.g. one can trivially combine Structs and add additional fields).
50 """!Create a Struct with the specified field names and values
55 strVal = 'the value of the field named "strVal"',
60 @param[in] **keyArgs keyword arguments specifying name=value pairs
63 for name, val
in keyArgs.items():
66 def __safeAdd(self, name, val):
67 """!Add a field if it does not already exist and name does not start with __ (two underscores)
69 @param[in] name name of field to add
70 @param[in] val value of field to add
72 @throw RuntimeError if name already exists or starts with __ (two underscores)
74 if hasattr(self, name):
75 raise RuntimeError(
"Item %s already exists" % (name,))
76 if name.startswith(
"__"):
77 raise RuntimeError(
"Item name %r invalid; must not begin with __" % (name,))
78 setattr(self, name, val)
81 """!Return a dictionary of attribute name: value
83 @warning: the values are shallow copies.
85 return self.__dict__.copy()
88 """!Copy specified fields from another struct, provided they don't already exist
90 @param[in] struct struct from which to copy
91 @param[in] *nameList all remaining arguments are names of items to copy
93 For example: foo.copyItems(other, "itemName1", "itemName2")
94 copies other.itemName1 and other.itemName2 into self.
96 @throw RuntimeError if any item in nameList already exists in self
97 (but any items before the conflicting item in nameList will have been copied)
100 self.
__safeAdd(name, getattr(struct, name))
103 """!Return a one-level-deep copy (values are not copied)
108 return self.
__dict__ == other.__dict__
114 itemList = [
"%s=%r" % (name, val)
for name, val
in self.
getDict().items()]
115 return "%s(%s)" % (self.__class__.__name__,
"; ".join(itemList))
def __init__
Create a Struct with the specified field names and values.
def copy
Return a one-level-deep copy (values are not copied)
A struct to which you can add any fields.
def __safeAdd
Add a field if it does not already exist and name does not start with __ (two underscores) ...
def getDict
Return a dictionary of attribute name: value.
def mergeItems
Copy specified fields from another struct, provided they don't already exist.