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Typo Suggestions#

TLDR, How to enable#

Enable the feature with appRunner.UseTypoSuggestions() or appRunner.UseDefaultMiddleware().

Introduction#

When a user types in a command or option that does not exist, this feature will suggest similar commands or options in case the user made a typo.

λ fakegit commish
'commish' is not a valid subcommand

Did you mean ...
   commit

See 'fakegit --help'
~
λ fakegit commit --brash
'brash' is not a valid option

Did you mean ...
   --branch

See 'fakegit commit --help'

Operand names will never be suggested as they are never entered by the user.

When the typo is prefixed with -- then similar options will be suggested, else similar commands are suggested.

Option short names are not included in typo suggestions.

Suggestions for argument values#

When IArgument.AllowedValues is populated, TypoSuggestions will offer suggestions based on the allowed values as well.

IArgument.AllowedValues are populated by TypeDescriptors implementing IAllowedValuesTypeDescriptor which currently includes bool and enum types.

λ schedule-task --day Mondday
'Mondday' is not a valid DayOfWeek

Did you mean ...
   Monday

See 'schedule-task --help'

To provide AllowedValues for other types, you can

  • create a TypeDescriptors for your type
  • subscribe to OnCommandCreated to update arguments as they're added
    • appRunner.Configure(c => c.BuildEvents.OnCommandCreated += args => a.CommandBuilder.Command.Options ... /*set AllowedValues*/)
  • add middleware to set the IArgument.AllowedValues after MiddlewareSteps.ParseInput
    • appRunner.Configure(c => c.UseMiddleware((ctx,next)=> ctx.ParseResult.TargetCommand.Options ... /*set AllowedValues*/, MiddlewareSteps.ParseInput + 100))
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