Connections control the transfer of information between layers.

Making a created connection into a working connection requires 4 steps. Autoconnect does all four of these.

1. Attach both ends to the relevant layers, i.e., target attach conn and conn attach source.
2. Identify the relevant conversion. The automatic value for this is the same as that given by the find_conversion command between the representations of the two layers. This conversion could be in either direction. Where both representations have a “natural” pattern that is a localist_pattern (e.g., keyed_representation, or blocked_representation with keyed_representation inner) the option for converting from source layer's representation to the target layer's representations is explored first (and the reverse second); for all other combinations, this preference is reversed. I'm not sure why this is the case, but it helped with something once upon a time.
3. Subtype the connection. The appropriate subtype is determined by (a) the direction of the conversion, (b) the subtype of the conversion, © the “natural” pattern of the source representation, and (d) the “natural” pattern of the target representation. Running the list_conversion_connections method on any conversion will give the prevailing rules.
4. “Fill” the connection. This refers to any set-up operation on the connection from the conversion, such as filling the values of a matrix. This process may fail. Upon failure, the autoconnect process would go back to stage 2 and uses the reverse conversion (if that option has not already been tried).

some_conn description

The description of some_conn contains additional elements: Source indicates the layer whose output is pulled. Target indicates the layer that pulls information through the connection, and has the sub-element port for the input channel on the layer used. Autoconnect? indicates whether the connection will be automatically filled on a change in source and target layers. Lag describing the time differential between the output of the source and the input of the target for any information.

some_conn lesion

Insert a lesioned_connection_impl into the connection_impl slot of some_conn without destroying the existing connection_impl facet (which now becomes the responsiblity of the lesioned_connection_impl facet to manage; this is used in its unlesion method).

some_conn autoconnect src_layer tgt_layer port

Disable the autoconnect bit on some_conn; attach some_conn as a source of tgt_layer on the port port; reenable the autoconnect bit on some_conn; and attach src_layer as the source of some_conn, triggering autoconnection.

some_conn autoconnect src_layer tgt_layer

As above, but port 0 (usually net_input) is used, rather than port.

some_conn attach src_layer

Attach src_layer as the source of some_conn.

some_conn detach

Unset the source of some_conn

some_conn set_autoconnect 0
some_conn set_autoconnect 1

Indicate that the autoconnection mechanism should (1) or should not (0) be triggered when the source or target layer changes.

some_conn set_lag nsteps

Set the amount of time between source and output of some_conn to be nsteps.

some_conn source

Return the source layer of some_conn.

some_conn get_labels

List the dimension names of the representation of the target layer of some_conn.

some_conn conv_connect the_conv

Only effective if both a source and target layer are connected to some_conn. Select a connection_impl for some_conn on the basis of the representations at the source and target layer and format (fill) it using the_conv; that is, use the manually selected the_conv instead of the conversion from stage 2 above, and perform stages 3 and 4. Turns off autoconnection on further changes to source or target layer.

some_conn conv_fill the_conv

Only effective if both a source and target layer are connected to some_conn, and a connection_impl is already in place. Format (fill) the current connection_impl of some_conn using the_conv. That is, accept the current subtype of connection instead of selected one automatically, as use the_conv to perform stage 4 above. Turns off autoconnection on further changes to source or target layer.