1717
1818from opentelemetry .context .context import Context
1919
20- TextMapPropagatorT = typing .TypeVar ("TextMapPropagatorT " )
20+ CarrierT = typing .TypeVar ("CarrierT " )
2121CarrierValT = typing .Union [typing .List [str ], str ]
2222
23- Setter = typing .Callable [[TextMapPropagatorT , str , str ], None ]
2423
25-
26- class Getter (typing .Generic [TextMapPropagatorT ]):
24+ class Getter (abc .ABC ):
2725 """This class implements a Getter that enables extracting propagated
2826 fields from a carrier.
2927 """
3028
29+ @abc .abstractmethod
3130 def get (
32- self , carrier : TextMapPropagatorT , key : str
31+ self , carrier : CarrierT , key : str
3332 ) -> typing .Optional [typing .List [str ]]:
3433 """Function that can retrieve zero
3534 or more values from the carrier. In the case that
@@ -42,9 +41,9 @@ def get(
4241 Returns: first value of the propagation key or None if the key doesn't
4342 exist.
4443 """
45- raise NotImplementedError ()
4644
47- def keys (self , carrier : TextMapPropagatorT ) -> typing .List [str ]:
45+ @abc .abstractmethod
46+ def keys (self , carrier : CarrierT ) -> typing .List [str ]:
4847 """Function that can retrieve all the keys in a carrier object.
4948
5049 Args:
@@ -53,17 +52,33 @@ def keys(self, carrier: TextMapPropagatorT) -> typing.List[str]:
5352 Returns:
5453 list of keys from the carrier.
5554 """
56- raise NotImplementedError ()
5755
5856
59- class DictGetter (Getter [typing .Dict [str , CarrierValT ]]):
60- def get (
61- self , carrier : typing .Dict [str , CarrierValT ], key : str
57+ class Setter (abc .ABC ):
58+ """This class implements a Setter that enables injecting propagated
59+ fields into a carrier.
60+ """
61+
62+ @abc .abstractmethod
63+ def set (self , carrier : CarrierT , key : str , value : str ) -> None :
64+ """Function that can set a value into a carrier""
65+
66+ Args:
67+ carrier: An object which contains values that are used to
68+ construct a Context.
69+ key: key of a field in carrier.
70+ value: value for a field in carrier.
71+ """
72+
73+
74+ class DefaultGetter (Getter ):
75+ def get ( # type: ignore
76+ self , carrier : typing .Mapping [str , CarrierValT ], key : str
6277 ) -> typing .Optional [typing .List [str ]]:
6378 """Getter implementation to retrieve a value from a dictionary.
6479
6580 Args:
66- carrier: dictionary in which header
81+ carrier: dictionary in which to get value
6782 key: the key used to get the value
6883 Returns:
6984 A list with a single string with the value if it exists, else None.
@@ -75,11 +90,36 @@ def get(
7590 return list (val )
7691 return [val ]
7792
78- def keys (self , carrier : typing .Dict [str , CarrierValT ]) -> typing .List [str ]:
93+ def keys ( # type: ignore
94+ self , carrier : typing .Dict [str , CarrierValT ]
95+ ) -> typing .List [str ]:
7996 """Keys implementation that returns all keys from a dictionary."""
8097 return list (carrier .keys ())
8198
8299
100+ default_getter = DefaultGetter ()
101+
102+
103+ class DefaultSetter (Setter ):
104+ def set ( # type: ignore
105+ self ,
106+ carrier : typing .MutableMapping [str , CarrierValT ],
107+ key : str ,
108+ value : CarrierValT ,
109+ ) -> None :
110+ """Setter implementation to set a value into a dictionary.
111+
112+ Args:
113+ carrier: dictionary in which to set value
114+ key: the key used to set the value
115+ value: the value to set
116+ """
117+ carrier [key ] = value
118+
119+
120+ default_setter = DefaultSetter ()
121+
122+
83123class TextMapPropagator (abc .ABC ):
84124 """This class provides an interface that enables extracting and injecting
85125 context into headers of HTTP requests. HTTP frameworks and clients
@@ -92,9 +132,9 @@ class TextMapPropagator(abc.ABC):
92132 @abc .abstractmethod
93133 def extract (
94134 self ,
95- getter : Getter [TextMapPropagatorT ],
96- carrier : TextMapPropagatorT ,
135+ carrier : CarrierT ,
97136 context : typing .Optional [Context ] = None ,
137+ getter : Getter = default_getter ,
98138 ) -> Context :
99139 """Create a Context from values in the carrier.
100140
@@ -120,25 +160,25 @@ def extract(
120160 @abc .abstractmethod
121161 def inject (
122162 self ,
123- set_in_carrier : Setter [TextMapPropagatorT ],
124- carrier : TextMapPropagatorT ,
163+ carrier : CarrierT ,
125164 context : typing .Optional [Context ] = None ,
165+ setter : Setter = default_setter ,
126166 ) -> None :
127167 """Inject values from a Context into a carrier.
128168
129169 inject enables the propagation of values into HTTP clients or
130170 other objects which perform an HTTP request. Implementations
131- should use the set_in_carrier method to set values on the
171+ should use the `Setter` 's set method to set values on the
132172 carrier.
133173
134174 Args:
135- set_in_carrier: A setter function that can set values
136- on the carrier.
137175 carrier: An object that a place to define HTTP headers.
138- Should be paired with set_in_carrier , which should
176+ Should be paired with setter , which should
139177 know how to set header values on the carrier.
140178 context: an optional Context to use. Defaults to current
141179 context if not set.
180+ setter: An optional `Setter` object that can set values
181+ on the carrier.
142182
143183 """
144184
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