Implement async checks. Fixes #380.

discord/ext/commands/bot.py

@@ -85,7 +85,7 @@ def _default_help_command(ctx, *commands : str):
 
     # help by itself just lists our own commands.
     if len(commands) == 0:
-        pages = bot.formatter.format_help_for(ctx, bot)
+        pages = yield from bot.formatter.format_help_for(ctx, bot)
     elif len(commands) == 1:
         # try to see if it is a cog name
         name = _mention_pattern.sub(repl, commands[0])
@@ -98,7 +98,7 @@ def _default_help_command(ctx, *commands : str):
                 yield from destination.send(bot.command_not_found.format(name))
                 return
 
-        pages = bot.formatter.format_help_for(ctx, command)
+        pages = yield from bot.formatter.format_help_for(ctx, command)
     else:
         name = _mention_pattern.sub(repl, commands[0])
         command = bot.commands.get(name)
@@ -117,7 +117,7 @@ def _default_help_command(ctx, *commands : str):
                 yield from destination.send(bot.command_has_no_subcommands.format(command, key))
                 return
 
-        pages = bot.formatter.format_help_for(ctx, command)
+        pages = yield from bot.formatter.format_help_for(ctx, command)
 
     if bot.pm_help is None:
         characters = sum(map(lambda l: len(l), pages))
@@ -218,9 +218,9 @@ class BotBase(GroupMixin):
         on a per command basis except it is run before any command checks
         have been verified and applies to every command the bot has.
 
-        .. warning::
+        .. info::
 
-            This function must be a *regular* function and not a coroutine.
+            This function can either be a regular function or a coroutine.
 
         Similar to a command :func:`check`\, this takes a single parameter
         of type :class:`Context` and can only raise exceptions derived from
@@ -268,8 +268,12 @@ class BotBase(GroupMixin):
         except ValueError:
             pass
 
+    @asyncio.coroutine
     def can_run(self, ctx):
-        return all(f(ctx) for f in self._checks)
+        if len(self._checks) == 0:
+            return True
+
+        return (yield from discord.utils.async_all(f(ctx) for f in self._checks))
 
     def before_invoke(self, coro):
         """A decorator that registers a coroutine as a pre-invoke hook.

discord/ext/commands/core.py

@@ -342,6 +342,7 @@ class Command:
                 raise TooManyArguments('Too many arguments passed to ' + self.qualified_name)
 
 
+    @asyncio.coroutine
     def _verify_checks(self, ctx):
         if not self.enabled:
             raise DisabledCommand('{0.name} command is disabled'.format(self))
@@ -349,10 +350,7 @@ class Command:
         if self.no_pm and not isinstance(ctx.channel, discord.abc.GuildChannel):
             raise NoPrivateMessage('This command cannot be used in private messages.')
 
-        if not ctx.bot.can_run(ctx):
-            raise CheckFailure('The global check functions for command {0.qualified_name} failed.'.format(self))
-
-        if not self.can_run(ctx):
+        if not (yield from self.can_run(ctx)):
             raise CheckFailure('The check functions for command {0.qualified_name} failed.'.format(self))
 
     @asyncio.coroutine
@@ -402,7 +400,7 @@ class Command:
     @asyncio.coroutine
     def prepare(self, ctx):
         ctx.command = self
-        self._verify_checks(ctx)
+        yield from self._verify_checks(ctx)
         yield from self._parse_arguments(ctx)
 
         if self._buckets.valid:
@@ -533,14 +531,17 @@ class Command:
             return self.help.split('\n', 1)[0]
         return ''
 
-    def can_run(self, context):
-        """Checks if the command can be executed by checking all the predicates
+    @asyncio.coroutine
+    def can_run(self, ctx):
+        """|coro|
+
+        Checks if the command can be executed by checking all the predicates
         inside the :attr:`checks` attribute.
 
         Parameters
         -----------
-        context : :class:`Context`
-            The context of the command currently being invoked.
+        ctx: :class:`Context`
+            The ctx of the command currently being invoked.
 
         Returns
         --------
@@ -548,6 +549,9 @@ class Command:
             A boolean indicating if the command can be invoked.
         """
 
+        if not (yield from ctx.bot.can_run(ctx)):
+            raise CheckFailure('The global check functions for command {0.qualified_name} failed.'.format(self))
+
         cog = self.instance
         if cog is not None:
             try:
@@ -555,14 +559,16 @@ class Command:
             except AttributeError:
                 pass
             else:
-                if not local_check(context):
+                ret = yield from discord.utils.maybe_coroutine(local_check, ctx)
+                if not ret:
                     return False
 
         predicates = self.checks
         if not predicates:
             # since we have no checks, then we just return True.
             return True
-        return all(predicate(context) for predicate in predicates)
+
+        return (yield from discord.utils.async_all(predicate(ctx) for predicate in predicates))
 
 class GroupMixin:
     """A mixin that implements common functionality for classes that behave
@@ -855,6 +861,10 @@ def check(predicate):
     will be propagated while those subclassed will be sent to
     :func:`on_command_error`.
 
+    .. info::
+
+        These functions can either be regular functions or coroutines.
+
     Parameters
     -----------
     predicate

discord/ext/commands/formatter.py

@@ -26,9 +26,11 @@ DEALINGS IN THE SOFTWARE.
 
 import itertools
 import inspect
+import asyncio
 
 from .core import GroupMixin, Command
 from .errors import CommandError
+# from discord.iterators import _FilteredAsyncIterator
 
 # help -> shows info of bot on top/bottom and lists subcommands
 # help command -> shows detailed info of command
@@ -227,6 +229,7 @@ class HelpFormatter:
         return "Type {0}{1} command for more info on a command.\n" \
                "You can also type {0}{1} category for more info on a category.".format(self.clean_prefix, command_name)
 
+    @asyncio.coroutine
     def filter_command_list(self):
         """Returns a filtered list of commands based on the two attributes
         provided, :attr:`show_check_failure` and :attr:`show_hidden`. Also
@@ -238,8 +241,9 @@ class HelpFormatter:
             An iterable with the filter being applied. The resulting value is
             a (key, value) tuple of the command name and the command itself.
         """
-        def predicate(tuple):
-            cmd = tuple[1]
+
+        def sane_no_suspension_point_predicate(tup):
+            cmd = tup[1]
             if self.is_cog():
                 # filter commands that don't exist to this cog.
                 if cmd.instance is not self.command:
@@ -248,18 +252,31 @@ class HelpFormatter:
             if cmd.hidden and not self.show_hidden:
                 return False
 
-            if self.show_check_failure:
-                # we don't wanna bother doing the checks if the user does not
-                # care about them, so just return true.
-                return True
+            return True
+
+        @asyncio.coroutine
+        def predicate(tup):
+            if sane_no_suspension_point_predicate(tup) is False:
+                return False
 
+            cmd = tup[1]
             try:
-                return cmd.can_run(self.context) and self.context.bot.can_run(self.context)
+                return (yield from cmd.can_run(self.context))
             except CommandError:
                 return False
 
         iterator = self.command.commands.items() if not self.is_cog() else self.context.bot.commands.items()
-        return filter(predicate, iterator)
+        if not self.show_check_failure:
+            return filter(sane_no_suspension_point_predicate, iterator)
+
+        # Gotta run every check and verify it
+        ret = []
+        for elem in iterator:
+            valid = yield from predicate(elem)
+            if valid:
+                ret.append(elem)
+
+        return ret
 
     def _add_subcommands_to_page(self, max_width, commands):
         for name, command in commands:
@@ -271,6 +288,7 @@ class HelpFormatter:
             shortened = self.shorten(entry)
             self._paginator.add_line(shortened)
 
+    @asyncio.coroutine
     def format_help_for(self, context, command_or_bot):
         """Formats the help page and handles the actual heavy lifting of how
         the help command looks like. To change the behaviour, override the
@@ -290,8 +308,9 @@ class HelpFormatter:
         """
         self.context = context
         self.command = command_or_bot
-        return self.format()
+        return (yield from self.format())
 
+    @asyncio.coroutine
     def format(self):
         """Handles the actual behaviour involved with formatting.
 
@@ -334,18 +353,19 @@ class HelpFormatter:
             # last place sorting position.
             return cog + ':' if cog is not None else '\u200bNo Category:'
 
+        filtered = yield from self.filter_command_list()
         if self.is_bot():
-            data = sorted(self.filter_command_list(), key=category)
+            data = sorted(filtered, key=category)
             for category, commands in itertools.groupby(data, key=category):
                 # there simply is no prettier way of doing this.
-                commands = list(commands)
+                commands = sorted(commands)
                 if len(commands) > 0:
                     self._paginator.add_line(category)
 
                 self._add_subcommands_to_page(max_width, commands)
         else:
             self._paginator.add_line('Commands:')
-            self._add_subcommands_to_page(max_width, self.filter_command_list())
+            self._add_subcommands_to_page(max_width, sorted(filtered))
 
         # add the ending note
         self._paginator.add_line()

discord/iterators.py

@@ -30,18 +30,11 @@ import aiohttp
 import datetime
 
 from .errors import NoMoreItems
-from .utils import time_snowflake
+from .utils import time_snowflake, maybe_coroutine
 from .object import Object
 
 PY35 = sys.version_info >= (3, 5)
 
-@asyncio.coroutine
-def _probably_coroutine(f, e):
-    if asyncio.iscoroutinefunction(f):
-        return (yield from f(e))
-    else:
-        return f(e)
-
 class _AsyncIterator:
     __slots__ = ()
 
@@ -67,7 +60,7 @@ class _AsyncIterator:
             except NoMoreItems:
                 return None
 
-            ret = yield from _probably_coroutine(predicate, elem)
+            ret = yield from maybe_coroutine(predicate, elem)
             if ret:
                 return elem
 
@@ -114,7 +107,7 @@ class _MappedAsyncIterator(_AsyncIterator):
     def get(self):
         # this raises NoMoreItems and will propagate appropriately
         item = yield from self.iterator.get()
-        return (yield from _probably_coroutine(self.func, item))
+        return (yield from maybe_coroutine(self.func, item))
 
 class _FilteredAsyncIterator(_AsyncIterator):
     def __init__(self, iterator, predicate):
@@ -132,7 +125,7 @@ class _FilteredAsyncIterator(_AsyncIterator):
         while True:
             # propagate NoMoreItems similar to _MappedAsyncIterator
             item = yield from getter()
-            ret = yield from _probably_coroutine(pred, item)
+            ret = yield from maybe_coroutine(pred, item)
             if ret:
                 return item
 

discord/utils.py

@@ -260,3 +260,19 @@ def _bytes_to_base64_data(data):
 def to_json(obj):
     return json.dumps(obj, separators=(',', ':'), ensure_ascii=True)
 
+@asyncio.coroutine
+def maybe_coroutine(f, e):
+    if asyncio.iscoroutinefunction(f):
+        return (yield from f(e))
+    else:
+        return f(e)
+
+@asyncio.coroutine
+def async_all(gen):
+    check = asyncio.iscoroutine
+    for elem in gen:
+        if check(elem):
+            elem = yield from elem
+        if not elem:
+            return False
+    return True