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# Description
The meaning of the word usage is specific to describing how a command
function is *used* and not a synonym for general description. Usage can
be used to describe the SYNOPSIS or EXAMPLES sections of a man page
where the permitted argument combinations are shown or example *uses*
are given.
Let's not confuse people and call it what it is a description.
Our `help` command already creates its own *Usage* section based on the
available arguments and doesn't refer to the description with usage.
# User-Facing Changes
`help commands` and `scope commands` will now use `description` or
`extra_description`
`usage`-> `description`
`extra_usage` -> `extra_description`
Breaking change in the plugin protocol:
In the signature record communicated with the engine.
`usage`-> `description`
`extra_usage` -> `extra_description`
The same rename also takes place for the methods on
`SimplePluginCommand` and `PluginCommand`
# Tests + Formatting
- Updated plugin protocol specific changes
# After Submitting
- [ ] update plugin protocol doc
81 lines
3.0 KiB
Rust
81 lines
3.0 KiB
Rust
use nu_engine::command_prelude::*;
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use nu_protocol::engine::CommandType;
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#[derive(Clone)]
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pub struct Def;
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impl Command for Def {
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fn name(&self) -> &str {
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"def"
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}
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fn description(&self) -> &str {
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"Define a custom command."
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}
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fn signature(&self) -> nu_protocol::Signature {
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Signature::build("def")
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.input_output_types(vec![(Type::Nothing, Type::Nothing)])
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.required("def_name", SyntaxShape::String, "Command name.")
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.required("params", SyntaxShape::Signature, "Parameters.")
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.required("block", SyntaxShape::Closure(None), "Body of the definition.")
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.switch("env", "keep the environment defined inside the command", None)
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.switch("wrapped", "treat unknown flags and arguments as strings (requires ...rest-like parameter in signature)", None)
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.category(Category::Core)
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}
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fn extra_description(&self) -> &str {
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r#"This command is a parser keyword. For details, check:
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https://www.nushell.sh/book/thinking_in_nu.html"#
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}
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fn command_type(&self) -> CommandType {
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CommandType::Keyword
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}
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fn run(
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&self,
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_engine_state: &EngineState,
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_stack: &mut Stack,
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_call: &Call,
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_input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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Ok(PipelineData::empty())
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}
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fn examples(&self) -> Vec<Example> {
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vec![
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Example {
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description: "Define a command and run it",
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example: r#"def say-hi [] { echo 'hi' }; say-hi"#,
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result: Some(Value::test_string("hi")),
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},
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Example {
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description: "Define a command and run it with parameter(s)",
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example: r#"def say-sth [sth: string] { echo $sth }; say-sth hi"#,
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result: Some(Value::test_string("hi")),
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},
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Example {
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description: "Set environment variable by call a custom command",
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example: r#"def --env foo [] { $env.BAR = "BAZ" }; foo; $env.BAR"#,
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result: Some(Value::test_string("BAZ")),
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},
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Example {
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description: "cd affects the environment, so '--env' is required to change directory from within a command",
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example: r#"def --env gohome [] { cd ~ }; gohome; $env.PWD == ('~' | path expand)"#,
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result: Some(Value::test_string("true")),
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},
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Example {
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description: "Define a custom wrapper for an external command",
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example: r#"def --wrapped my-echo [...rest] { ^echo ...$rest }; my-echo -e 'spam\tspam'"#,
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result: Some(Value::test_string("spam\tspam")),
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},
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Example {
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description: "Define a custom command with a type signature. Passing a non-int value will result in an error",
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example: r#"def only_int []: int -> int { $in }; 42 | only_int"#,
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result: Some(Value::test_int(42)),
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},
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]
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}
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}
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