自定义命令

def nullify [...cols] {
  let start = $in
  $cols | reduce --fold $start { |col, table|
    $table | upsert $col null
  }
}

ls | nullify name size
# => ╭───┬──────┬──────┬──────┬───────────────╮
# => │ # │ name │ type │ size │   modified    │
# => ├───┼──────┼──────┼──────┼───────────────┤
# => │ 0 │      │ dir  │      │ 8 minutes ago │
# => │ 1 │      │ file │      │ 8 minutes ago │
# => │ 2 │      │ file │      │ 8 minutes ago │
# => │ 3 │      │ file │      │ 8 minutes ago │
# => ╰───┴──────┴──────┴──────┴───────────────╯

def if [] { "my if" }
# => Error: nu::parser::name_is_keyword
# =>
# =>   × Can't use parser keyword `if` as command name.
# =>    ╭─[repl_entry #1:1:5]
# =>  1 │ def if [] { "my if" }
# =>    ·     ─┬
# =>    ·      ╰── 'if' is a parser keyword
# =>    ╰────
# =>   help: Parser keywords cannot be shadowed (including via module exports and `use *`). Choose a different command name so language constructs keep working.

def greet [] { "hi" }
%greet
# => Error: nu::parser::error
# =>
# =>   × percent sigil requires a built-in command
# =>    ╭─[repl_entry #1:2:2]
# =>  1 │ def greet [] { "hi" }
# =>  2 │ %greet
# =>    ·  ──┬──
# =>    ·    ╰── unknown built-in command
# =>    ╰────
# =>   help: remove `%` to use normal resolution, or use `^` to run an external command explicitly

def greet [name1, name2] {
  $"Hello, ($name1) and ($name2)!"
}

greet Wei Mei
# => Hello, Wei and Mei!

greet Wei
# => Error: nu::parser::missing_positional
# =>
# =>   × Missing required positional argument.
# =>    ╭─[repl_entry #3:1:10]
# =>  1 │ greet Wei
# =>    ╰────
# =>   help: Usage: greet <name1> <name2> . Use `--help` for more information.

greet World
# => Error: nu::parser::parse_mismatch
# =>
# =>   × Parse mismatch: expected int.
# =>    ╭─[repl_entry #2:1:7]
# =>  1 │ greet World
# =>    ·       ──┬──
# =>    ·         ╰── expected int
# =>    ╰────
# =>   help: Check the syntax around this position — a typo, missing delimiter, or wrong separator is common.

type Point = record<x: float, y: float>
def length-of [p: Point]: nothing -> float { ($p.x ** 2 + $p.y ** 2) | math sqrt }

length-of {x: 1, y: 2}
# => Error: nu::parser::type_mismatch
# =>
# =>   × Type mismatch.
# =>    ╭─[repl_entry #3:1:11]
# =>  1 │ length-of {x: 1, y: 2}
# =>    ·           ──────┬─────
# =>    ·                 ╰── expected record<x: float, y: float>, found record<x: int, y: int>
# =>    ╰────

greet Lucia --age 23
# => ╭──────┬───────╮
# => │ name │ Lucia │
# => │ age  │ 23    │
# => ╰──────┴───────╯

greet --age 39 Ali
# => ╭──────┬─────╮
# => │ name │ Ali │
# => │ age  │ 39  │
# => ╰──────┴─────╯

greet World
# => ╭──────┬───────╮
# => │ name │ World │
# => │ age  │       │
# => ╰──────┴───────╯

def greet [
  name: string
  --caps
] {
    let greeting = $"Hello, ($name)!"
    if $caps {
      $greeting | str uppercase
    } else {
      $greeting
    }
}

greet Miguel --caps
# => HELLO, MIGUEL!

greet Chukwuemeka
# => Hello, Chukwuemeka!

def greet [
  name: string
  --all-caps
] {
    let greeting = $"Hello, ($name)!"
    if $all_caps {
      $greeting | str uppercase
    } else {
      $greeting
    }
}

def multi-greet [...names: string] {
  for $name in $names {
    print $"Hello, ($name)!"
  }
}

multi-greet Elin Lars Erik
# => Hello, Elin!
# => Hello, Lars!
# => Hello, Erik!

def vip-greet [vip: string, ...names: string] {
  for $name in $names {
    print $"Hello, ($name)!"
  }

  print $"And a special welcome to our VIP today, ($vip)!"
}

#         $vip          $name
#         ----- -------------------------
vip-greet Rahul Priya Arjun Anjali Vikram
# => Hello, Priya!
# => Hello, Arjun!
# => Hello, Anjali!
# => Hello, Vikram!
# => And a special welcome to our VIP today, Rahul!

def --wrapped ezal [...rest] {
  if '-G' in $rest {
    eza ...$rest
  } else {
    eza -l --icons ...$rest
  }
}

ezal -G commands
# => categories  docs  README.md

# 问候客人和一位贵宾
#
# 用于生日、毕业派对、
# 退休，以及任何其他
# 庆祝特定人物事件的
# 活动。
def vip-greet [
  vip: string        # 特别嘉宾
   ...names: string  # 其他客人
] {
  for $name in $names {
    print $"Hello, ($name)!"
  }

  print $"And a special welcome to our VIP today, ($vip)!"
}

# 问候客人和一位贵宾
#
# 用于生日、毕业派对、
# 退休，以及任何其他
# 庆祝特定人物事件的
# 活动。
@example "Greet a VIP" {vip-greet "Bob"} --result "And a special welcome to our VIP today, Bob!"
@example "Greet multiple people" {vip-greet "Bob" "Alice" "Charlie"} --result "Hello, Alice!
Hello, Charlie!
And a special welcome to our VIP today, Bob!"
def vip-greet [
  vip: string        # 特别嘉宾
   ...names: string  # 其他客人
] {
  for $name in $names {
    print $"Hello, ($name)!"
  }

  print $"And a special welcome to our VIP today, ($vip)!"
}

@deprecated
def greet [
  name: string
  --all-caps
] {
    let greeting = $"Hello, ($name)!"
    if $all_caps {
      $greeting | str uppercase
    } else {
      $greeting
    }
}

greet "bob"
# => Warning: nu::parser::deprecated
# =>
# =>   ⚠ Command deprecated.
# =>    ╭─[repl_entry #2:1:1]
# =>  1 │ greet "bob"
# =>    · ─────┬─────
# =>    ·      ╰── greet is deprecated and will be removed in a future release.
# =>    ╰────
# =>
# => Hello, bob!

@deprecated "Use vip-greet as a replacement." --report every
@category "deprecated"
def greet [
  name: string
  --all-caps
] {
    let greeting = $"Hello, ($name)!"
    if $all_caps {
      $greeting | str uppercase
    } else {
      $greeting
    }
}

greet bob
# => Warning: nu::parser::deprecated
# =>
# =>   ⚠ Command deprecated.
# =>    ╭─[repl_entry #2:1:1]
# =>  1 │ greet bob
# =>    · ────┬────
# =>    ·     ╰── greet is deprecated and will be removed in a future release.
# =>    ╰────
# =>   help: Use vip-greet as a replacement.
# =>
# => Hello, bob!

help commands | where category == deprecated | select name category command_type
# => ╭───┬───────┬────────────┬──────────────╮
# => │ # │ name  │  category  │ command_type │
# => ├───┼───────┼────────────┼──────────────┤
# => │ 0 │ greet │ deprecated │ custom       │
# => ╰───┴───────┴────────────┴──────────────╯