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(elisp)Transaction Queues

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Transaction Queues
==================

   You can use a "transaction queue" to communicate with a subprocess
using transactions.  First use `tq-create' to create a transaction
queue communicating with a specified process.  Then you can call
`tq-enqueue' to send a transaction.

 - Function: tq-create process
     This function creates and returns a transaction queue
     communicating with PROCESS.  The argument PROCESS should be a
     subprocess capable of sending and receiving streams of bytes.  It
     may be a child process, or it may be a TCP connection to a server,
     possibly on another machine.

 - Function: tq-enqueue queue question regexp closure fn
     This function sends a transaction to queue QUEUE.  Specifying the
     queue has the effect of specifying the subprocess to talk to.

     The argument QUESTION is the outgoing message that starts the
     transaction.  The argument FN is the function to call when the
     corresponding answer comes back; it is called with two arguments:
     CLOSURE, and the answer received.

     The argument REGEXP is a regular expression that should match text
     at the end of the entire answer, but nothing before; that's how
     `tq-enqueue' determines where the answer ends.

     The return value of `tq-enqueue' itself is not meaningful.

 - Function: tq-close queue
     Shut down transaction queue QUEUE, waiting for all pending
     transactions to complete, and then terminate the connection or
     child process.

   Transaction queues are implemented by means of a filter function.
Note: Filter Functions.