[nongnu] elpa/sesman e83fcfd939 002/100: Add readme

[ELPA Syncer]

branch: elpa/sesman
commit e83fcfd9399a75586cb713128bceb845252ba9e5
Author: Vitalie Spinu <spinuvit@gmail.com>
Commit: Vitalie Spinu <spinuvit@gmail.com>

    Add readme
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+## Generic session manager for Emacs
+
+This is a brief overview. Please see the code for more details.
+
+Sesman provides facilities for session management and interactive session 
association with current contexts. While "sessions" is a broad and 
implementation specific concept, the primary target of `sesman` are Emacs based 
IDEs ([CIDER][], [ESS][], [Geiser][], [Robe][], [SLIME][] etc.)
+
+For Emacs based IDEs, session is commonly composed of one or more physical 
processes (sub-processes, sockets, websockets etc). For example in the current 
implementation of [CIDER][] a session would be composed of one or more cider 
connections (Clojre or ClojureScript). Each [CIDER][] connection consists of 
user REPL buffer and two processes, one for user eval communication and another 
for tooling (completion, inspector etc).
+
+### Concepts:
+
+  - "session" is a list of the form `(session-name ..other-stuff..)` where 
`..other-stuff..` is system dependent.
+  - "system" is generic name used for the tools which uses sesman (e.g. 
`CIDER`, `ESS` etc)
+  - "contexts" are Emacs objects which describe current context. For example 
`current-buffer`, `default-directory` and `project-current` are such contexts. 
Context objects are used to create associations (links) between the current 
context and sessions. At any given time the user can link/unlink sessions 
to/from contexts. By default there are three types of contexts - buffer, 
directory and project, but systems can define their own contexts as they see 
fit.
+  
+Sesman is composed of two parts, [user interface][], available as [sesman 
map][], and [system interface][] consisting of a few generic functions which 
systems should define. 
+
+### [User Interface][]
+
+Consists of 
+
+ - lifecycle management commands (`sesman-start`, `sesman-kill` and 
`sesman-restart`), and
+ - association management commands (`sesman-link-with-buffer`, 
`sesman-link-with-directory`, `sesman-link-with-project` and `sesman-unlink`). 
+
+From the user's prospective the work-flow is simple. Start a session, either 
with `sesman-start` (`C-c C-s C-s`) or some of the system specific commands 
(`run-xyz`, `xyz-jack-in` etc). On startup each session is automatically 
associated with the least specific context (commonly a project). In the most 
common case the user has one session open per project; thus, no ambiguity 
arises when the system retrieves current session. If none or multiple sessions 
are associated with current context, [...]
+
+Currently there is only one custom variable, `sesman-1-to-1-links`, which 
lists context types for which `1-to-1` associations are desired (defaults to 
`'(directory buffer)`. This means, that each time the user links a session with 
a directory, any previous associations with that directory are lost. For 
context types not in this list (e.g. `project`), 1-to-many associations are 
allowed. 
+
+### [System Interface][]
+
+Consists of several generics, of which only first two are strictly required:
+
+  - `sesman-start-session`
+  - `sesman-kill-session`
+  - `sesman-restart-session` - defaults to `sesman-start-session` + 
`sesman-kill-session`
+  - `sesman-greater-p` - used for sorting sessions in "recency" order
+  - `sesman-friendly-session-p` - used to define friendly sessions (such as 
projects which are dependencies of other projects)
+  
+Depending on the purpose, sesman system can use several functions to retrieve 
sessions (`sesman-ensure-session`, `sesman-linked-sessions`, 
`sesman-friendly-sessions`, `sesman-system-sessions` and `sesman-sessions`). 
Most important of these being `sesman-ensure-session` which should be used to 
ensure that at least one session is linked to the current context. It returns 
the most specific session given sesman associations already in place. In case 
of ambiguity (or no sessions) the user is  [...]
+
+Systems could directly use user level commands to manage sessions 
(`sesman-start`, `sesman-kill`) or use legacy system specific initializer 
(`run-xyz`, `xyz-jack-in` etc). In the latter case, systems should call 
`sesman-register` to register their sessions with `sesman`.
+
+Systems should link [semsna map][] into their modes' key-maps (ideally on `C-c 
C-s`, which is a good mnemonic, is free in CIDER and already does similar 
things in ESS).
+
+
+[user interface]: https://github.com/vspinu/sesman/blob/master/sesman.el#L53
+[system interface]: https://github.com/vspinu/sesman/blob/master/sesman.el#L133
+[sesman map]: https://github.com/vspinu/sesman/blob/master/sesman.el#L112-L130
+
+[cider]: https://github.com/clojure-emacs/cider
+[ess]: https://ess.r-project.org/
+[geiser]: https://github.com/jaor/geiser
+[robe]: https://github.com/dgutov/robe
+[slime]: https://common-lisp.net/project/slime/