Source code for SCons.Variables.BoolVariable

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"""Variable type for true/false Variables.

Usage example::

    opts = Variables()
    opts.Add(BoolVariable('embedded', 'build for an embedded system', False))
    env = Environment(variables=opts)
    if env['embedded']:
        ...
"""

from typing import Tuple, Callable

import SCons.Errors

__all__ = ['BoolVariable',]

TRUE_STRINGS = ('y', 'yes', 'true', 't', '1', 'on', 'all')
FALSE_STRINGS = ('n', 'no', 'false', 'f', '0', 'off', 'none')


[docs]def _text2bool(val: str) -> bool: """Convert boolean-like string to boolean. If *val* looks like it expresses a bool-like value, based on the :const:`TRUE_STRINGS` and :const:`FALSE_STRINGS` tuples, return the appropriate value. This is usable as a converter function for SCons Variables. Raises: ValueError: if *val* cannot be converted to boolean. """ lval = val.lower() if lval in TRUE_STRINGS: return True if lval in FALSE_STRINGS: return False # TODO: leave this check to validator? raise ValueError(f"Invalid value for boolean variable: {val!r}")
[docs]def _validator(key, val, env) -> None: """Validate that the value of *key* in *env* is a boolean. Parameter *val* is not used in the check. Usable as a validator function for SCons Variables. Raises: KeyError: if *key* is not set in *env* UserError: if the value of *key* is not ``True`` or ``False``. """ if env[key] not in (True, False): msg = f'Invalid value for boolean variable {key!r}: {env[key]}' raise SCons.Errors.UserError(msg) from None
# lint: W0622: Redefining built-in 'help' (redefined-builtin)
[docs]def BoolVariable(key, help: str, default) -> Tuple[str, str, str, Callable, Callable]: """Return a tuple describing a boolean SCons Variable. The input parameters describe a boolean variable, using a string value as described by :const:`TRUE_STRINGS` and :const:`FALSE_STRINGS`. Returns a tuple including the correct converter and validator. The *help* text will have ``(yes|no)`` automatically appended to show the valid values. The result is usable as input to :meth:`~SCons.Variables.Variables.Add`. """ help = f'{help} (yes|no)' return key, help, default, _validator, _text2bool
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