# MIT License
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# Copyright The SCons Foundation
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"""Variable type for package Variables.
To be used whenever a 'package' may be enabled/disabled and the
package path may be specified.
Given these options ::
x11=no (disables X11 support)
x11=yes (will search for the package installation dir)
x11=/usr/local/X11 (will check this path for existence)
Can be used as a replacement for autoconf's ``--with-xxx=yyy`` ::
opts = Variables()
opts.Add(
PackageVariable(
key='x11',
help='use X11 installed here (yes = search some places)',
default='yes'
)
)
env = Environment(variables=opts)
if env['x11'] is True:
dir = ... # search X11 in some standard places ...
env['x11'] = dir
if env['x11']:
... # build with x11 ...
"""
import os
from typing import Callable, Optional, Tuple, Union
import SCons.Errors
__all__ = ['PackageVariable',]
ENABLE_STRINGS = ('1', 'yes', 'true', 'on', 'enable', 'search')
DISABLE_STRINGS = ('0', 'no', 'false', 'off', 'disable')
[docs]
def _converter(val: Union[str, bool]) -> Union[str, bool]:
"""Convert package variables.
Returns True or False if one of the recognized truthy or falsy
values is seen, else return the value unchanged (expected to
be a path string).
"""
if isinstance(val, bool):
# mainly for the subst=False case: default might be a bool
return val
lval = val.lower()
if lval in ENABLE_STRINGS:
return True
if lval in DISABLE_STRINGS:
return False
return val
[docs]
def _validator(key: str, val, env, searchfunc) -> None:
"""Validate package variable for valid path.
Checks that if a path is given as the value, that pathname actually exists.
"""
# NOTE: searchfunc is currently undocumented and unsupported
if env[key] is True:
if searchfunc:
env[key] = searchfunc(key, val)
# TODO: need to check path, or be sure searchfunc raises.
elif env[key] and not os.path.exists(val):
msg = f'Path does not exist for variable {key!r}: {val!r}'
raise SCons.Errors.UserError(msg) from None
# lint: W0622: Redefining built-in 'help' (redefined-builtin)
[docs]
def PackageVariable(
key: str, help: str, default, searchfunc: Optional[Callable] = None
) -> Tuple[str, str, str, Callable, Callable]:
"""Return a tuple describing a package list SCons Variable.
The input parameters describe a 'package list' variable. Returns
a tuple with the correct converter and validator appended.
The result is usable as input to :meth:`~SCons.Variables.Variables.Add`.
A 'package list' variable may either be a truthy string from
:const:`ENABLE_STRINGS`, a falsy string from
:const:`DISABLE_STRINGS`, or a pathname string.
This information is appended to *help* using only one string
each for truthy/falsy.
"""
# NB: searchfunc is currently undocumented and unsupported
help = '\n '.join((help, f'( yes | no | /path/to/{key} )'))
return (
key,
help,
default,
lambda k, v, e: _validator(k, v, e, searchfunc),
_converter,
)
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