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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
102 lines
3.2 KiB
Rust
102 lines
3.2 KiB
Rust
use nu_engine::command_prelude::*;
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#[derive(Clone)]
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pub struct Print;
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impl Command for Print {
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fn name(&self) -> &str {
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"print"
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}
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fn signature(&self) -> Signature {
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Signature::build("print")
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.input_output_types(vec![
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(Type::Nothing, Type::Nothing),
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(Type::Any, Type::Nothing),
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])
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.allow_variants_without_examples(true)
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.rest("rest", SyntaxShape::Any, "the values to print")
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.switch(
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"no-newline",
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"print without inserting a newline for the line ending",
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Some('n'),
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)
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.switch("stderr", "print to stderr instead of stdout", Some('e'))
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.switch(
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"raw",
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"print without formatting (including binary data)",
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Some('r'),
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)
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.category(Category::Strings)
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}
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fn description(&self) -> &str {
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"Print the given values to stdout."
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}
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fn extra_description(&self) -> &str {
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r#"Unlike `echo`, this command does not return any value (`print | describe` will return "nothing").
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Since this command has no output, there is no point in piping it with other commands.
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`print` may be used inside blocks of code (e.g.: hooks) to display text during execution without interfering with the pipeline."#
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["display"]
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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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let args: Vec<Value> = call.rest(engine_state, stack, 0)?;
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let no_newline = call.has_flag(engine_state, stack, "no-newline")?;
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let to_stderr = call.has_flag(engine_state, stack, "stderr")?;
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let raw = call.has_flag(engine_state, stack, "raw")?;
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// This will allow for easy printing of pipelines as well
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if !args.is_empty() {
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for arg in args {
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if raw {
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arg.into_pipeline_data()
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.print_raw(engine_state, no_newline, to_stderr)?;
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} else {
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arg.into_pipeline_data()
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.print(engine_state, stack, no_newline, to_stderr)?;
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}
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}
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} else if !input.is_nothing() {
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if raw {
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input.print_raw(engine_state, no_newline, to_stderr)?;
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} else {
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input.print(engine_state, stack, no_newline, to_stderr)?;
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}
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}
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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: "Print 'hello world'",
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example: r#"print "hello world""#,
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result: None,
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},
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Example {
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description: "Print the sum of 2 and 3",
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example: r#"print (2 + 3)"#,
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result: None,
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},
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Example {
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description: "Print 'ABC' from binary data",
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example: r#"0x[41 42 43] | print --raw"#,
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result: None,
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},
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]
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}
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}
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