chainlet.chainlink module¶
-
class
chainlet.chainlink.
ChainLink
¶ Bases:
object
BaseClass for elements in a chain
A chain is created by binding
ChainLink
s together. This is a directional process: a binding is always made between parent and child. Each child can be the parent to another child, and vice versa.The direction dictates how data is passed along the chain:
- A parent may
send()
a data chunk to a child. - A child may pull the
next()
data chunk from the parent.
Chaining is done with
>>
and<<
operators asparent >> child
andchild << parent
. Forking and joining of chains requires a sequence of multiple elements as parent or child.-
parent >> child
-
child << parent
Bind
child
andparent
. Both directions of the statement are equivalent: ifa
is made a child ofb
, then b` is made a parent ofa
, and vice versa.
-
parent >> (child_a, child_b, ...)
-
parent >> [child_a, child_b, ...]
-
parent >> {child_a, child_b, ...}
Bind
child_a
,child_b
, etc. as children ofparent
.
-
(parent_a, parent_b, ...) >> child
-
[parent_a, parent_b, ...] >> child
-
{parent_a, parent_b, ...} >> child
Bind
parent_a
,parent_b
, etc. as parents ofchild
.
Aside from binding, every
ChainLink
implements the Generator-Iterator Methods interface:-
iter
(link)¶ Create an iterator over all data chunks that can be created. Empty results are ignored.
-
link.
__next__
()¶ -
link.
send
(None)¶ -
next
(link)¶ Create a new chunk of data. Raise
StopIteration
if there are no more chunks. Implicitly used bynext(link)
.
-
link.
send
(chunk) Process a data
chunk
, and return the result.
Note
The
next
variants contrast withiter
by also returning empty chunks. Use variations ofnext(iter(link))
for an explicit iteration.-
link.
chainlet_send
(chunk)¶ Process a data
chunk
locally, and return the result.This method implements data processing in an element; subclasses must overwrite it to define how they handle data.
This method should only be called to explicitly traverse elements in a chain. Client code should use
next(link)
andlink.send(chunk)
instead.
-
link.
throw
(type[, value[, traceback]])¶ Raises an exception of
type
inside the link. The link may either return a final result (includingNone
), raiseStopIteration
if there are no more results, or propagate any other, unhandled exception.
-
link.
close
()¶ Close the link, cleaning up any resources.. A closed link may raise
RuntimeError
if data is requested vianext
or processed viasend
.
When used in a chain, each
ChainLink
is distinguished by its handling of input and output. There are two attributes to signal the behaviour when chained. These specify whether the element performs a 1 -> 1, n -> 1, 1 -> m or n -> m processing of data.-
chain_join
¶ A
bool
indicating that the element expects the values of all preceding elements at once. That is, the chunk passed in viasend()
is an iterable providing the return values of the previous elements.
-
chain_fork
¶ A
bool
indicating that the element produces several values at once. That is, the return value is an iterable of data chunks, each of which should be passed on independently.
To prematurely stop the traversal of a chain, 1 -> n and n -> m elements should return an empty container. Any 1 -> 1 and n -> 1 element must raise
StopTraversal
.-
chain_fork
= False whether this element produces several data chunks at once
-
chain_join
= False whether this element processes several data chunks at once
-
chain_types
= <chainlet.chainlink.LinkPrimitives object>¶
-
chainlet_send
(value=None)¶ Send a value to this element for processing
-
close
()¶ Close this element, freeing resources and blocking further interactions
-
dispatch
(values)¶ Dispatch multiple values to this element for processing
-
next
()
-
send
(value=None)¶ Send a single value to this element for processing
-
static
throw
(type, value=None, traceback=None)¶ Throw an exception in this element
- A parent may