feature(workspace builder): Add shell-configuration to pane layer (#672)

* Added the ability to specify `shell` per pane.

Had to implement the special case for the first pane. In that case the
shell for the window that is created has to be overridden.

This also fixed a bug (in my opinion) that `window_shell` only affected
the first pane, and none of the other panes in a window.

The system unfortunatelly still bailes out, when the specified shell is
not executable (e.g. doesn't even exist). The problem is an unhandeled
exception when the information for the pane can't be extracted (as it
never really started). Not sure how to catch that and provide a sensible
message to the user.

* Added an example for the pane-shell configuration.

* Added the documentation to the example.md file instead.

As the examples.rst files was replaced by the md-files in the main line.

Author: jerri

docs/examples.md

@@ -307,6 +307,26 @@ without `window_index` will use the lowest available window index.
 
 ```
 
+## Shell per pane
+
+Every pane can have its own shell or application started. This allows for usage
+of the ``remain-on-exit`` setting to be used properly, but also to have
+different shells on different panes.
+
+### YAML
+
+```{literalinclude} ../examples/pane-shell.yaml
+:language: yaml
+
+```
+
+### JSON
+
+```{literalinclude} ../examples/pane-shell.json
+:language: json
+
+```
+
 ## Set tmux options
 
 Works with global (server-wide) options, session options

examples/pane-shell.json

@@ -0,0 +1,40 @@
+{
+  "session_name": "Pane shell example",
+  "windows": [
+    {
+      "window_name": "first",
+      "window_shell": "/usr/bin/python2",
+      "layout": "even-vertical",
+      "suppress_history": false,
+      "options": {
+        "remain-on-exit": true
+      },
+      "panes": [
+        {
+          "shell": "/usr/bin/python3",
+          "shell_command": [
+            "print('This is python 3')"
+          ]
+        },
+        {
+          "shell": "/usr/bin/vim -u none",
+          "shell_command": [
+            "iAll panes have the `remain-on-exit` setting on.",
+            "When you exit out of the shell or application, the panes will remain.",
+            "Use tmux command `:kill-pane` to remove the pane.",
+            "Use tmux command `:respawn-pane` to restart the shell in the pane.",
+            "Use <Escape> and then `:q!` to get out of this vim window. :-)"
+          ]
+        },
+        {
+          "shell_command": [
+            "print('Hello World 2')"
+          ]
+        },
+        {
+          "shell": "/usr/bin/top"
+        }
+      ]
+    }
+  ]
+}

examples/pane-shell.yaml

@@ -0,0 +1,22 @@
+session_name: Pane shell example
+windows:
+  - window_name: first
+    window_shell: /usr/bin/python2
+    layout: even-vertical
+    suppress_history: false
+    options:
+      remain-on-exit: true
+    panes:
+      - shell: /usr/bin/python3
+        shell_command:
+          - print('This is python 3')
+      - shell: /usr/bin/vim -u none
+        shell_command:
+          - iAll panes have the `remain-on-exit` setting on.
+          - When you exit out of the shell or application, the panes will remain.
+          - Use tmux command `:kill-pane` to remove the pane.
+          - Use tmux command `:respawn-pane` to restart the shell in the pane.
+          - Use <Escape> and then `:q!` to get out of this vim window. :-)
+      - shell_command:
+          - print('Hello World 2')
+      - shell: /usr/bin/top

tmuxp/workspacebuilder.py

@@ -265,6 +265,13 @@ def iter_create_windows(self, session, append=False):
             else:
                 ws = None
 
+            # If the first pane specifies a shell, use that instead.
+            try:
+                if wconf['panes'][0]['shell'] != '':
+                    ws = wconf['panes'][0]['shell']
+            except (KeyError, IndexError):
+                pass
+
             w = session.new_window(
                 window_name=window_name,
                 start_directory=sd,
@@ -328,8 +335,20 @@ def get_pane_start_directory():
                     else:
                         return None
 
+                def get_pane_shell():
+
+                    if 'shell' in pconf:
+                        return pconf['shell']
+                    elif 'window_shell' in wconf:
+                        return wconf['window_shell']
+                    else:
+                        return None
+
                 p = w.split_window(
-                    attach=True, start_directory=get_pane_start_directory(), target=p.id
+                    attach=True,
+                    start_directory=get_pane_start_directory(),
+                    shell=get_pane_shell(),
+                    target=p.id
                 )
 
             assert isinstance(p, Pane)