CommandLineError variantv0.1.0

Why the arguments did not match the command.

pub variant CommandLineError {
    UnknownOption(OsStringView),
    MissingValue(char8[..]),
    UnexpectedValue(char8[..]),
    UnknownCommand(OsStringView),
    MissingCommand,
    MissingPositional(char8[..]),
    UnexpectedArgument(OsStringView),
    InvalidValue(char8[..], OsStringView)
}

Failure-only: a parse is the success channel of Parsed ! CommandLineError. Copy; every view and name it carries borrows the arguments or the specification, which must outlive it.

Cases

Name	Description
`UnknownOption(OsStringView)`	An argument that looks like an option names none the command has. Carries the argument as typed.
`MissingValue(char8[..])`	An option that takes a value was the last argument, or ended a cluster of short options. Carries the option's long name.
`UnexpectedValue(char8[..])`	A flag was given a value with `=`. Carries the option's long name.
`UnknownCommand(OsStringView)`	The command has subcommands and the word naming one is not among them. Carries the word as typed.
`MissingCommand`	The command has subcommands and none was named.
`MissingPositional(char8[..])`	A required positional argument was not given. Carries its name.
`UnexpectedArgument(OsStringView)`	A positional argument beyond every one the command accepts. Carries the argument as typed.
`InvalidValue(char8[..], OsStringView)`	A value that could not be read as what was asked of it, such as a number. Carries the option or positional's name, then the value as typed.

Implements Display

CommandLineError conforms to Display.

`WriteDisplay`

pub func WriteDisplay(
    self: &CommandLineError,
    writer: &var TextWriter,
    spec: FormatSpec
) -> ! FormatError

Writes what went wrong, naming the argument, option or positional involved. The text is lower case without a final full stop, such as unknown option '--frob' or option '--output' needs a value. No style is understood. Reports whatever the writer reported, and UnsupportedRequest for a style.

Name	Type	Description
`writer`	`&var TextWriter`	the destination
`spec`	`FormatSpec`	what the placeholder asked for

Returns: success when the whole description was accepted

Source

Implements Debug

CommandLineError conforms to Debug.

`WriteDebug`

pub func WriteDebug(
    self: &CommandLineError,
    writer: &var TextWriter,
    spec: FormatSpec
) -> ! FormatError

The same text as Display: the description already names everything involved. The failures WriteDisplay reports.

Name	Type	Description
`writer`	`&var TextWriter`	the destination
`spec`	`FormatSpec`	what the placeholder asked for

Returns: success when the whole description was accepted

Source

Overview

Declarative command-line parsing: options, positional arguments, subcommands and generated help

Parsed

Arguments that matched a command.

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