# 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
# Description
When implementing a `Command`, one must also import all the types
present in the function signatures for `Command`. This makes it so that
we often import the same set of types in each command implementation
file. E.g., something like this:
```rust
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
ShellError, Signature, Span, Type, Value,
};
```
This PR adds the `nu_engine::command_prelude` module which contains the
necessary and commonly used types to implement a `Command`:
```rust
// command_prelude.rs
pub use crate::CallExt;
pub use nu_protocol::{
ast::{Call, CellPath},
engine::{Command, EngineState, Stack},
record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, IntoSpanned,
PipelineData, Record, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
};
```
This should reduce the boilerplate needed to implement a command and
also gives us a place to track the breadth of the `Command` API. I tried
to be conservative with what went into the prelude modules, since it
might be hard/annoying to remove items from the prelude in the future.
Let me know if something should be included or excluded.
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# Description
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Related issue and PR, #11825#11864
This improves the signature of `commandline`.
## Before
`commandline` returns different types depending on the flags and an
aurgument.
| command | input | output | description |
|-----------------------------|---------|---------|----------------------------------------|
| `commandline` | nothing | string | get current cursor line |
| `commandline arg` | nothing | nothing | replace the cursor line with
`arg` |
| `commandline --append arg` | nothing | nothing | append `arg` to the
end of cursor line |
| `commandline --insert arg` | nothing | nothing | insert `arg` to the
position of cursor |
| `commandline --replace arg` | nothing | nothing | replace the cursor
line with `arg` |
| `commandline --cursor` | nothing | int | get current cursor position |
| `commandline --cursor pos` | nothing | nothing | set cursor position
to pos |
| `commandline --cursor-end` | nothing | nothing | set cursor position
to end |
`help commandline` shows that `commandline` accepts string as pipeline
input, but `commandline` ignores pipeline input.
```
Input/output types:
╭───┬─────────┬─────────╮
│ # │ input │ output │
├───┼─────────┼─────────┤
│ 0 │ nothing │ nothing │
│ 1 │ string │ string │
╰───┴─────────┴─────────╯
```
671bd08bcd/crates/nu-cli/src/commands/commandline.rs (L70)
This is misleading.
Due to the change #11864 , typecheck does not work well.
https://github.com/nushell/nushell/pull/11864#discussion_r1491814054
## After
Separate `commandline` into subcommands so that each subcommands returns
the same type for the same input type.
| command | input | output | description |
|----------------------------------|---------|---------|----------------------------------------|
| `commandline` | nothing | string | get current cursor line |
| `commandline edit arg` | nothing | nothing | replace the cursor line
with `arg` |
| `commandline edit --append arg` | nothing | nothing | append `arg` to
the end of cursor line |
| `commandline edit --insert arg` | nothing | nothing | insert `arg` to
the position of cursor |
| `commandline edit --replace arg` | nothing | nothing | replace the
cursor line with `arg` |
| `commandline get-cursor` | nothing | int | get current cursor position
|
| `commandline set-cursor pos` | nothing | nothing | set cursor position
to pos |
| `commandline set-cursor --end` | nothing | nothing | set cursor
position to end |
# User-Facing Changes
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# Tests + Formatting
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# After Submitting
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