# iex_history2
Improved shell history with variable binding persistance.
* Saves shell history between VM/shell.
* Saves the shell variable bindings between VM/shell restarts.
* Ability to paste (most) terms into the shell.
* Navigation keys allow history traversal where multi-line pastes require a single key up/down.
* Shortcut functions permit search, pasting, re-evaluation and editing of items in history.
* Editing can be done in-situ or in a text editor.
* Shell variable bindings can be set/get outside of scope of the shell to assist in application debugging.
* Can be enabled and state shared globally, or on individual shell sessions.
See section on `Configuration` and `Initialization` to get started.
## Navigation Keys
The default navigation keys are defined below. They can however be configured to alternative values if so desired.
```
ctrl^u - Move up through history.
ctrl^k - Move down through history.
ctrl^y - Allows the currently displayed item to be modified.
ctrl^l - Opens the currently displayed item in an editor.
ctrl^[ - Reset navigation, returns to the prompt.
```
NOTE: To use `ctrl^l` the environment variable EDITOR must be set to point to your editor:
```
export EDITOR="vim"
```
## Shortcut Search and Edit Functions
Key history navigation functions are automatically imported into the shell.
```
iex> hl() - Will list the entire history.
iex> hl(val) - Will list `val` entries from the start if val is positive, or from the end if negative.
iex> hl(start, stop) - Will list entries between `start` and `stop`.
iex> hs(string) - Will list entries that match all or part the query string.
iex> hsi(string) - Case insensitive list entries that match all or part of the query string.
iex> hsa(string, dist \\ 80) - Closest match list of entries, e.g "acr.to_str" == "Macro.to_string"
iex> hx(pos) - Will execute the expression at position `pos`.
iex> hc(pos) - Will copy the expression at position pos to the shell.
iex> he(pos) - Edit the expression in a text editor.
iex> hb() - Displays the current bindings.
iex> hi() - Summary
```
NOTE: To use `he/1` the environment variable EDITOR must be set to point to the editor:
```
export EDITOR="vim"
```
### iex> hl()
Displays the entire history.
```
iex> hl()
1: 2023-09-01 17:29:27: time = Time.utc_now().second
2: 2023-09-01 17:29:31: time = Time.utc_now().second
3: 2023-09-01 17:29:36: time
4: 2023-09-01 17:29:41: new_time
5: 2023-09-01 17:50:10: Process.info self
6: 2023-09-01 17:50:33: r = o
7: 2023-09-01 17:52:36: Process.get(:iex_history)
```
### iex> hl(val)
If the argument is a positive integer it displays the command at that index.
If the argument is a negative number it displays the history that many items from the end.
```
iex> hl(2)
2: 2023-09-01 17:29:31: time = Time.utc_now().second
iex> IExHistory2.h(-3)
5: 2023-09-01 17:50:10: Process.info self
6: 2023-09-01 17:50:33: r = o
7: 2023-09-01 17:52:36: Process.get(:iex_history)
```
### iex> hl(start, stop)
Specify a range, the atoms :start and :stop can also be used.
### iex> hs(match)
Will search history for anything that matches the passed string.
```
iex> hs("Applic")
34: 2023-09-01 18:10:39: Application.put_env(:kernel, :shell_history, :disabled)
41: 2023-09-01 18:11:30: Application.get_env(:kernel, :shell_history)
48: 2023-09-01 18:14:02: Application.put_env(:kernel, :shell_history, 0)
101: 2023-09-01 19:01:15: :rpc.call(:erlang.node(Process.group_leader()), Application, :put_env, [:kernel, :shell_history, :disabled])
103: 2023-09-01 19:01:30: :rpc.call(:erlang.node(Process.group_leader()), Application, :put_env, [:kernel, :shell_history, :enabled])
```
### iex> hsi(match)
Case insensitive version of `hs/1`.
### iex> hsa(match, closeness \\ 80)
Like `hsa/1` a case insensitive search, but also adds a closeness element to the search.
It uses a combination of Myers Difference and Jaro Distance to get close to a match. The estimated
closeness is indicated in the result with a default range of > 80%. This can be set by the user.
```
iex> hsa("map_rdce")
786: 83% 2024-01-27 15:01:05: h(Enum.map_reduce)
806: 83% 2024-01-27 15:21:49: h(Enum.map_reduce)
826: 83% 2024-01-27 16:19:24: h(Enum.map_reduce)
```
### iex> hx(idx)
Invokes the command at index 'i'.
```
iex> hl(114)
114: 2023-09-01 19:30:14: Enum.count([1, 2, 3])
iex> hx(114)
iex> Enum.count([1, 2, 3])
3
```
### iex> hc(idx)
Copies the command at index 'i' and pastes it to the shell.
```
iex> hl(114)
114: 2023-09-01 19:30:14: Enum.count([1, 2, 3])
iex> hc(114)
:ok
iex> Enum.count([1, 2, 3])
```
### iex> he(idx)
Usefull for large terms or pasted modules. Will open the historical item in a text editor, ensuring
the result is re-evaluated and returned to the shell.
```
iex> he(114)
.....
.....
{:ok, :changes_made}
```
NOTE: To use `he/1` the environment variable EDITOR must be set to point to the editor:
```
export EDITOR="vim"
```
### iex> hb()
Shows the variable bindings.
### iex> hi()
Status summary.
## Binding Functions
The functions IExHistory2.add_binding/2 and IExHistory2.get_binding/1 allows variables to be
set in a module that is invoked in the shell to be accessible in the shell.
### IExHistory2.add_binding/2
This helper function can be used when testing code (for example a module pasted
into the shell). It allows a variable to be set that will become available in
the shell. For example:
```
defmodule VarTest do
def set_me(var) do
var = var * 2
IExHistory2.add_binding(:test_var, var)
var + 100
end
end
iex> VarTest.set_me(7)
iex> test_var
14
```
The variable can be represented as an atom or string.
### IExHistory2.get_binding/1
The inverse of `add_binding/2`
It allows a variable that is set in the shell to be available in a module under test. For example:
```
defmodule VarTest do
def get_me(val) do
if IExHistory2.get_binding(:path_to_use) == :path1 do
val + 100
else
val + 200
end
end
end
iex> path_to_use = :path1
:path1
iex> VarTest.get_me(50)
150
iex> path_to_use = :path2
:path2
iex> VarTest.get_me(50)
```
The complimentary functions `add_binding/3` and `get_binding/2` that take a shell pid or registered name allowing
the user to debug applications.
```
defmodule VarTest do
def get_me(val) do
if IExHistory2.get_binding(:path_to_use, :myshell) == :path1 do
result = val + 100
IExHistory2.add_binding(:result_var, %{path: :path1, result: result}, :myshell)
result
else
result = val + 200
IExHistory2.add_binding(:result_var, %{path: :path2, result: result}, :myshell)
result
end
end
end
iex> spawn(fn -> VarTest.get_me(100) end)
#PID<0.1557.0>
%{path: :path2, result: 300}
iex> result_var
%{path: :path2, result: 300}
```
See also `IExHistory2.register/1`.
## Misc Functions
### IExHistory2.initialize(opts)
Initializes the IExHistory2 app. See the `Configuration` section for options.
### IExHistory2.clear()
Clears the history and bindings. If scope is :global the IEx session needs restarting for the changes to take effect.
### IExHistory2.clear_history(range)
Clears the history only, if no argument all history is cleared, else history from 1 to value is cleared
### IExHistory2.clear_bindings()
Clears bindings only
### IExHistory2.unbind(vars)
Unbinds a variable or list of variables, varibales should be expressed as atoms
### IExHistory2.stop_clear()
Clears the history and bindings then stops the service. If scope is :global the IEx session needs restarting for the changes to take effect.
### IExHistory2.configuration()
Displays the current conifuration
### IExHistory2.configure/2
Allows the following options to be changed:
```
:show_date
:history_limit
:hide_history_commands,
:prepend_identifiers,
:command_display_width,
:save_invalid_results,
:key_buffer_history,
:colors
```
Examples:
```
IExHistory2.configure(:colors, [index: :blue])
IExHistory2.configure(:prepend_identifiers, true)
```
### IExHistory2.is_enabled?()
Returns true or false is IExHistory2 is enabled
## Configuration
The following options can be set:
### In `~/.iex.exs`:
```
[
colors: [
index: :red,
date: :green,
command: :yellow,
label: :red,
variable: :green,
binding: :cyan
],
command_display_width: 150,
hide_history_commands: true,
history_limit: :infinity,
import: true,
key_buffer_history: true,
navigation_keys: [
up: 21,
down: 11,
editor: 5,
modify: 8,
abandon: 27,
enter: 13
],
paste_eval_regex: ["#Reference", "#PID", "#Function", "#Ecto.Schema.Metadata", "#Port"],
prepend_identifiers: true,
save_bindings: true,
save_invalid_results: false,
scope: :local,
show_date: true
]
```
### Same options in `config/runtime.exs`:
```
config :iex_history2,
scope: :local,
history_limit: :infinity,
paste_eval_regex: [],
import: true,
...
```
To import short-cut functions set `import:` to true.
import: true
One issue with the current shell is the inconsistent ability to paste large terms into
the shell. Types such as process ids and references (`#PID<0.1234.0>`) cause the evaluator to fail.
`IExHistory2` will attempt to recognize and parse such terms during evaluation.
Currently process ids, references, anonymous functions, ports and `#Ecto.Schema.Metadata` are
supported by default. Additional terms can be added:
paste_eval_regex: ["#SpecialItem1", "#NewObject"]
This toggle true/false for calls to `IExHistory2.*` (and imports) from been saved.
hide_history_commands: true
If set to false, the default, commands that were evaluated incorrectly will not be saved.
save_invalid_results: false
If set to true will allow the user to scroll up (ctrl+u) or down (ctrl+k) through history.
key_buffer_history: true
Unlike the standard up/down arrow history where the up-arrow key has to be pressed multiple times to
traverse a large term, `IExHistory2` only requires a single up/down key, and the entire term can then
be edited.
The default navigation keys are defined above, but can be changed to any reasonable value. Please be aware
that certain key are reserved by the runtime and can not be used. The values should be set to decimal, the
example below sets opening the editor from `ctrl^l` to `ctrl^e`
navigation_keys: [editor: 5]
If this is enabled it will prepend identifiers when a call to `x = hx(val)` is issued.
prepend_identifiers: true
For example:
```
enabled:
iex> time = Time.utc_now().second
14
iex> new_time = IExHistory2.x(1)
22
iex> new_time
22 # New time is assigned to variable time
iex> time
13 # However, the original date variable is unchanged
iex> IExHistory2.h()
1: 2023-09-01 17:13:13: time = Time.utc_now().second
2: 2023-09-01 17:13:22: new_time = time = Time.utc_now().second # We see the binding to new_time
disabled:
iex> time = Time.utc_now().second
43
iex> new_time = IExHistory2.x(1)
50
iex> new_time # New time is assigned to variable time
50
iex> time
50 # However, this time the original time variable has also changed
iex> IExHistory2.h
1: 2023-09-01 17:17:43: time = Time.utc_now().second
2: 2023-09-01 17:17:50: time = Time.utc_now().second # We do not see the binding to new_time
```
`:scope` can be one of `:local, :global` or a `node()` name
If `scope` is `:local` (the default) history will be active on all shells, even those that are remotely connected, but the history for each shell will be unique
If `scope` is `node()` (e.g. `:mgr@localhost`) history will only be active on that shell
If `scope` is `:global` history will be shared between all shells. However the saving of variable bindings will be disabled along with the date/time in history
Furthermore, if a `scope` of `:global` is selected following kernel option must be set, either directly as VM options or via an environment variable:
## Initialization
### Using `.iex.exs`
It is recommended to configure and start using `.iex.exs`, for example:
```
IExHistory2.initialize(history_limit: :infinity,
scope: :local,
paste_eval_regex: ["#Extra"],
show_date: true,
colors: [index: :red])
```
### As part of another application
Add to `mix.exs` as a dependency:
```
{:iex_history2, "~> 5.2"}
```
Or:
```
{:iex_history2, github: "nhpip/iex_history2", tag: "5.2.0"},
```
Add the configuration to your application `config/runtime.exs`. For example:
```
config :iex_history2,
history_limit: 12345,
import: false,
scope: :local,
paste_eval_regex: ["#Extra"],
show_date: true,
colors: [index: :red])
```
When you connect your shell call `IExHistory2.initialize/0` (in `.iex.exs` or as a standalone call):
```
IExHistory2.initialize()
```
