Skip to content

types.middleware.transformers

Pad

Type transformation to pad a value to length with padding. Ensures that value will be at least length long. padding should be the same type as value, so the concatenation functions properly

Type Constraints

  • Support len()
  • Support + for concatenation (like str or list)

Example

import arc
from arc.types.middleware import Pad

@arc.command
def command(val: Annotated[str, Pad(6, 'b')])
    arc.print(val)

command()

$ python example.py a
abbbbbb
Source code in /home/runner/work/arc/arc/arc/types/middleware/transformers.py 
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
class Pad:
    """Type transformation to pad a value to `length` with `padding`.
    Ensures that value will be at least `length` long. `padding`
    should be the same type as value, so the concatenation functions properly

    ## Type Constraints
    - Support `len()`
    - Support `+` for concatenation (like `str` or `list`)

    ## Example
    ```py
    import arc
    from arc.types.middleware import Pad

    @arc.command
    def command(val: Annotated[str, Pad(6, 'b')])
        arc.print(val)

    command()
    ```

    ```console
    $ python example.py a
    abbbbbb
    ```
    """

    def __init__(
        self, length: int, padding: t.Any, side: t.Literal["left", "right"] = "right"
    ):
        self.length = length
        self.padding = padding
        self.side = side

    def __call__(self, value: PadProtocol) -> PadProtocol:
        if self.side == "right":
            while len(value) < self.length:
                value += self.padding
        else:
            while len(value) < self.length:
                value = self.padding + value

        return value

Round

Type Tranformation to round given input to ndigits

Type Contraints

  • Supports round()

Example

import arc
from arc.types.middleware import Round

@arc.command
def command(val: Annotated[float, Round(2)])
    arc.print(val)

command()

$ python example.py 1.123456789
1.23
Source code in /home/runner/work/arc/arc/arc/types/middleware/transformers.py 
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
class Round:
    """Type Tranformation to round given input to `ndigits`

    ## Type Contraints
    - Supports `round()`

    ## Example
    ```py
    import arc
    from arc.types.middleware import Round

    @arc.command
    def command(val: Annotated[float, Round(2)])
        arc.print(val)

    command()
    ```

    ```console
    $ python example.py 1.123456789
    1.23
    ```
    """

    __slots__ = ("ndigits",)

    def __init__(self, ndigits: int) -> None:
        self.ndigits = ndigits

    def __call__(self, value: t.SupportsRound[t.Any]) -> t.SupportsRound[t.Any]:
        return round(value, self.ndigits)

Truncate

Type transformation to truncate a value to length

Type Constraints

  • Support list-like slice access

Example

import arc
from arc.types.middleware import Truncate

@arc.command
def command(val: Annotated[str, Truncate(6)])
    arc.print(val)

command()

$ python example.py 'string longer than 6 chars'
string
Source code in /home/runner/work/arc/arc/arc/types/middleware/transformers.py 
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
class Truncate:
    """Type transformation to truncate a value to `length`

    ## Type Constraints
    - Support list-like slice access

    ## Example
    ```py
    import arc
    from arc.types.middleware import Truncate

    @arc.command
    def command(val: Annotated[str, Truncate(6)])
        arc.print(val)

    command()
    ```

    ```console
    $ python example.py 'string longer than 6 chars'
    string
    ```
    """

    def __init__(self, length: int):
        self.length = length

    def __call__(self, value: SupportsSlice) -> SupportsSlice:
        return value[0 : self.length]