* Allow commands to return a Task<RuntimeResult>
This allows bot developers to centralize command result logic by
using result data whether the command as successful or not.
Example usage:
```csharp
var _result = await Commands.ExecuteAsync(context, argPos);
if (_result is RuntimeResult result)
{
await message.Channel.SendMessageAsync(result.Reason);
}
else if (!_result.IsSuccess)
{
// Previous error handling
}
```
The RuntimeResult class can be subclassed too, for example:
```csharp
var _result = await Commands.ExecuteAsync(context, argPos);
if (_result is MySubclassedResult result)
{
var builder = new EmbedBuilder();
for (var pair in result.Data)
{
builder.AddField(pair.Key, pair.Value, true);
}
await message.Channel.SendMessageAsync("", embed: builder);
}
else if (_result is RuntimeResult result)
{
await message.Channel.SendMessageAsync(result.Reason);
}
else if (!_result.IsSuccess)
{
// Previous error handling
}
```
* Make RuntimeResult's ctor protected
* Make RuntimeResult abstract
It never really made sense to have it instantiable in the first place,
frankly.
* Allow arbitrary attributes to be added to commands
I still don't approve adding type info back into commands, so
I decided to use this solution for allowing arbitrary attributes to be
added to commands.
Add attributes property to ParameterBuilder
Add Attributes properties to info types
* Why on earth git
* Add using for system so that Attribute can be used
* C#7 features in commands, CommandInfo in ModuleBase
* Update TypeReaders with C#7 features and IServiceProvider
* Add best-choice command selection to CommandService
* Normalize type reader scores correctly
* Fix logic error and rebase onto dev
* Change GetMethod for SetMethod in ReflectionUtils
Should be checking against setters, not getters
* Ensure args/params scores do not overwhelm Priority
* Remove possibility of NaNs
* Add grouping of preconditions to allow for flexible precondition logic.
* Fix checking Module Preconditions twice (and none of the command's own)
* Fix command preconditions group 0 looping over every other precondition anyway #whoopsies
* Use custom message when a non-zero Precondition Group fails.
* Fix doc comment rendering.
* Refactor loops into local function
* Considering a new result type
* Switch to IReadOnlyCollection<T> and fix compiler errors
* Revert PreconditionResult -> IResult in return types - Change PreconditionResult to a class that PreconditionGroupResult inherits.
* Feedback on property name.
* Change grouping type int -> string
* Explicitly use an ordinal StringComparer
* Full stops on error messages
* Remove some sillyness.
* Remove unneeded using.
Parameter preconditions were always getting the empty service provider,
even when a custom one was provided in ExecuteAsync, which means that
preconditions which use services cannot work properly.
* Improve parameter precondition type safety
Also removes some terrible code which was left over when I first
implemented parameter preconditions. I don't know why that was there.
With this commit, parameter preconditions should be much safer as they
use generic methods instead of janky casting of objects.
* Remove generic CheckPreconditions method
