kovidgoyal/kitty · error · ValueError

{parts[1]} is not a number

Error message

{parts[1]} is not a number

What it means

The right-hand side of a spacing spec must be a float or the literal 'default'; float() failure raises ValueError '{parts[1]} is not a number'.

Source

Thrown at kitty/rc/set_spacing.py:60

        mapper[f'{q}-h'] = mapper[f'{q}-horizontal'] = f'{q}-left {q}-right'.split()
        mapper[f'{q}-v'] = mapper[f'{q}-vertical'] = f'{q}-top {q}-bottom'.split()
        for edge in ('left', 'top', 'right', 'bottom'):
            mapper[f'{q}-{edge}'] = [f'{q}-{edge}']
    settings: dict[str, float | None] = {}
    for spec in args:
        parts = spec.split('=', 1)
        if len(parts) != 2:
            raise ValueError(f'{spec} is not a valid setting')
        which = mapper.get(parts[0].lower())
        if not which:
            raise ValueError(f'{parts[0]} is not a valid edge specification')
        if parts[1].lower() == 'default':
            val = None
        else:
            try:
                val = float(parts[1])
            except Exception:
                raise ValueError(f'{parts[1]} is not a number')
        for q in which:
            settings[q] = val
    return settings


class SetSpacing(RemoteCommand):
    protocol_spec = __doc__ = """
    settings+/dict.spacing: An object mapping margins/paddings using canonical form {'margin-top': 50, 'padding-left': null} etc
    match_window/str: Window to change paddings and margins in
    match_tab/str: Tab to change paddings and margins in
    all/bool: Boolean indicating change paddings and margins everywhere or not
    configured/bool: Boolean indicating whether to change the configured paddings and margins. Must be True if reset is True
    """

    short_desc = 'Set window paddings and margins'
    desc = (
        'Set the paddings and margins for the specified windows (defaults to active window).'
        ' For example: :code:`margin=20` or :code:`padding-left=10` or :code:`margin-h=30`. The shorthand form sets'

View on GitHub (pinned to 6d5d0c4406)

Solutions

1. Use a bare number (interpreted as points) or 'default', e.g. 'margin=10' or 'margin=default'
2. Remove unit suffixes like px

Example fix

# before
kitten @set-spacing margin=10px
# after
kitten @set-spacing margin=10

def valid_val(v): 
    try: float(v); return True
    except ValueError: return v.lower()=='default'

def is_number_or_default(v: str) -> bool:
    if v.lower()=='default': return True
    try: float(v); return True
    return False

When it happens

Trigger: Passing non-numeric values like 'margin=wide' or 'padding=10px' (units are not accepted).

Common situations: Including units (px, em) or other text in the value.

Related errors

• {spec} is not a valid setting
• {parts[0]} is not a valid edge specification
• No colors specified
• Unknown type_of_input: {type_of_input}
• Unknown keys in multicell_command:

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/79f6368c2d8bb7cb. Report an issue: GitHub.