Merge pull request #1989 from xonsh/load-events

Load events

Makefile

@@ -0,0 +1,31 @@
+# Make GNU Make xonshy
+SHELL=xonsh
+.SHELLFLAGS=-c
+.ONESHELL:
+.SILENT:
+
+# Unlike normal makefiles: executes the entire body in one go under xonsh, and doesn't echo
+
+.PHONY: help
+help:
+	print("""
+	Utility file for xonsh project. Try these targets:
+	* amalgamate: Generate __amalgam__.py files
+	* clean: Remove generated files (namely, the amalgamations)
+	* xonsh/ply: Pull down most recent ply
+	""")
+
+xonsh/ply:
+	git subtree pull --prefix xonsh/ply https://github.com/dabeaz/ply.git master --squash
+
+
+.PHONY: clean
+clean:
+	find xonsh -name __amalgam__.py -delete -print
+
+.PHONY: amalgamate
+amalgamate:
+	sys.path.insert(0, '.')
+	import setup
+	setup.amalgamate_source()
+	_ = sys.path.pop(0)

news/load-events.rst

@@ -0,0 +1,14 @@
+**Added:**
+
+* Load events are now available
+* New events added: ``on_post_init``, ``on_pre_cmdloop``, ``on_pre_rc``, ``on_post_rc``, ``on_ptk_create``
+
+**Changed:** None
+
+**Deprecated:** None
+
+**Removed:** None
+
+**Fixed:** None
+
+**Security:** None

tests/test_events.py

@@ -3,10 +3,12 @@ import inspect
 import pytest
 from xonsh.events import EventManager, Event, LoadEvent
 
+
 @pytest.fixture
 def events():
     return EventManager()
 
+
 def test_event_calling(events):
     called = False
 
@@ -19,6 +21,7 @@ def test_event_calling(events):
 
     assert called == "eggs"
 
+
 def test_event_returns(events):
     called = 0
 
@@ -39,6 +42,7 @@ def test_event_returns(events):
     assert called == 2
     assert set(vals) == {1, 2}
 
+
 def test_validator(events):
     called = None
 
@@ -92,6 +96,7 @@ def test_transmogrify(events):
     assert len(events.on_test) == 1
     assert inspect.getdoc(events.on_test) == docstring
 
+
 def test_transmogrify_by_string(events):
     docstring = "Test event"
     events.doc('on_test', docstring)
@@ -110,6 +115,46 @@ def test_transmogrify_by_string(events):
     assert len(events.on_test) == 1
     assert inspect.getdoc(events.on_test) == docstring
 
+
+def test_load(events):
+    events.transmogrify('on_test', 'LoadEvent')
+    called = 0
+
+    @events.on_test
+    def on_test():
+        nonlocal called
+        called += 1
+
+    assert called == 0
+
+    events.on_test.fire()
+    assert called == 1
+
+    @events.on_test
+    def second():
+        nonlocal called
+        called += 1
+
+    assert called == 2
+
+def test_load_2nd_call(events):
+    events.transmogrify('on_test', 'LoadEvent')
+    called = 0
+
+    @events.on_test
+    def on_test():
+        nonlocal called
+        called += 1
+
+    assert called == 0
+
+    events.on_test.fire()
+    assert called == 1
+
+    events.on_test.fire()
+    assert called == 1
+
+
 def test_typos(xonsh_builtins):
     for name, ev in vars(xonsh_builtins.events).items():
         if 'pytest' in name:

update_ply.xsh

@@ -1,4 +0,0 @@
-#!/usr/bin/env xonsh
-
-# update the ply repo bundled with xonsh
-git subtree pull --prefix xonsh/ply https://github.com/dabeaz/ply.git master --squash

xonsh/events.py

@@ -144,7 +144,13 @@ class Event(AbstractEvent):
 class LoadEvent(AbstractEvent):
     """
     An event species where each handler is called exactly once, shortly after either the event is
-    fired or the handler is registered (whichever is later).
+    fired or the handler is registered (whichever is later). Additional firings are ignored.
+
+    Note: Does not support scatter/gather, due to never knowing when we have all the handlers.
+
+    Note: Maintains a strong reference to pargs/kwargs in case of the addition of future handlers.
+
+    Note: This is currently NOT thread safe.
     """
     def __init__(self):
         self._fired = set()
@@ -167,7 +173,11 @@ class LoadEvent(AbstractEvent):
 
         This has no effect if the element is already present.
         """
+        if self._hasfired:
+            self._call(item)
             self._fired.add(item)
+        else:
+            self._unfired.add(item)
 
     def discard(self, item):
         """
@@ -178,8 +188,22 @@ class LoadEvent(AbstractEvent):
         self._fired.discard(item)
         self._unfired.discard(item)
 
+    def _call(self, handler):
+        try:
+            handler(*self._pargs, **self._kwargs)
+        except Exception:
+            print_exception("Exception raised in event handler; ignored.")
+
     def fire(self, *pargs, **kwargs):
-        raise NotImplementedError("See #1550")
+        if self._hasfired:
+            return
+        self._pargs = pargs
+        self._kwargs = kwargs
+        while self._unfired:
+            handler = self._unfired.pop()
+            self._call(handler)
+        self._hasfired = True
+        return ()  # Entirely for API compatibility
 
 
 class EventManager:

xonsh/main.py

@@ -19,6 +19,57 @@ from xonsh.codecache import run_script_with_cache, run_code_with_cache
 from xonsh.xonfig import xonfig_main
 from xonsh.lazyimps import pygments, pyghooks
 from xonsh.imphooks import install_hook
+from xonsh.events import events
+
+
+events.transmogrify('on_post_init', 'LoadEvent')
+events.doc('on_post_init', """
+on_post_init() -> None
+
+Fired after all initialization is finished and we're ready to do work.
+
+NOTE: This is fired before the wizard is automatically started.
+""")
+
+events.transmogrify('on_exit', 'LoadEvent')
+events.doc('on_exit', """
+on_exit() -> None
+
+Fired after all commands have been executed, before tear-down occurs.
+
+NOTE: All the caveats of the atexit module also apply to this event.
+""")
+
+
+events.transmogrify('on_pre_cmdloop', 'LoadEvent')
+events.doc('on_pre_cmdloop', """
+on_pre_cmdloop() -> None
+
+Fired just before the command loop is started, if it is.
+""")
+
+events.transmogrify('on_post_cmdloop', 'LoadEvent')
+events.doc('on_post_cmdloop', """
+on_post_cmdloop() -> None
+
+Fired just after the command loop finishes, if it is.
+
+NOTE: All the caveats of the atexit module also apply to this event.
+""")
+
+events.transmogrify('on_pre_rc', 'LoadEvent')
+events.doc('on_pre_rc', """
+on_pre_rc() -> None
+
+Fired just before rc files are loaded, if they are.
+""")
+
+events.transmogrify('on_post_rc', 'LoadEvent')
+events.doc('on_post_rc', """
+on_post_rc() -> None
+
+Fired just before rc files are loaded, if they are.
+""")
 
 
 def get_setproctitle():
@@ -206,8 +257,10 @@ def main(argv=None):
     if argv is None:
         argv = sys.argv[1:]
     args = premain(argv)
+    events.on_post_init.fire()
     env = builtins.__xonsh_env__
     shell = builtins.__xonsh_shell__
+    try:
         if args.mode == XonshMode.interactive:
             # enter the shell
             env['XONSH_INTERACTIVE'] = True
@@ -218,7 +271,11 @@ def main(argv=None):
                 print('Could not find xonsh configuration or run control files.',
                       file=sys.stderr)
                 xonfig_main(['wizard', '--confirm'])
+            events.on_pre_cmdloop.fire()
+            try:
                 shell.shell.cmdloop()
+            finally:
+                events.on_post_cmdloop.fire()
         elif args.mode == XonshMode.single_command:
             # run a single command and exit
             run_code_with_cache(args.command.lstrip(), shell.execer, mode='single')
@@ -238,6 +295,8 @@ def main(argv=None):
             code = sys.stdin.read()
             run_code_with_cache(code, shell.execer, glb=shell.ctx, loc=None,
                                 mode='exec')
+    finally:
+        events.on_exit.fire()
     postmain(args)
 
 

xonsh/ptk/shell.py

@@ -20,6 +20,15 @@ from xonsh.ptk.completer import PromptToolkitCompleter
 from xonsh.ptk.history import PromptToolkitHistory
 from xonsh.ptk.key_bindings import load_xonsh_bindings
 from xonsh.ptk.shortcuts import Prompter
+from xonsh.events import events
+
+
+events.transmogrify('on_ptk_create', 'LoadEvent')
+events.doc('on_ptk_create', """
+on_ptk_create(prompter: Prompter, history: PromptToolkitHistory, completer: PromptToolkitCompleter, bindings: KeyBindingManager) ->
+
+Fired after prompt toolkit has been initialized
+""")
 
 
 class PromptToolkitShell(BaseShell):
@@ -37,6 +46,8 @@ class PromptToolkitShell(BaseShell):
             }
         self.key_bindings_manager = KeyBindingManager(**key_bindings_manager_args)
         load_xonsh_bindings(self.key_bindings_manager)
+        # This assumes that PromptToolkitShell is a singleton
+        events.on_ptk_create.fire(self.prompter, self.history, self.pt_completer, self.key_bindings_manager)
 
     def singleline(self, store_in_history=True, auto_suggest=None,
                    enable_history_search=True, multiline=True, **kwargs):

xonsh/shell.py

@@ -148,5 +148,7 @@ class Shell(object):
             # load run control files
             env = builtins.__xonsh_env__
             rc = env.get('XONSHRC') if rc is None else rc
+            events.on_pre_rc.fire()
             self.ctx.update(xonshrc_context(rcfiles=rc, execer=self.execer, initial=self.ctx))
+            events.on_post_rc.fire()
         self.ctx['__name__'] = '__main__'