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"""Variable type for path Variables.
To be used whenever a user-specified path override setting should be allowed.
Arguments to PathVariable are:
* *key* - name of this variable on the command line (e.g. "prefix")
* *help* - help string for variable
* *default* - default value for this variable
* *validator* - [optional] validator for variable value. Predefined are:
* *PathAccept* - accepts any path setting; no validation
* *PathIsDir* - path must be an existing directory
* *PathIsDirCreate* - path must be a dir; will create
* *PathIsFile* - path must be a file
* *PathExists* - path must exist (any type) [default]
The *validator* is a function that is called and which should return
True or False to indicate if the path is valid. The arguments
to the validator function are: (*key*, *val*, *env*). *key* is the
name of the variable, *val* is the path specified for the variable,
and *env* is the environment to which the Variables have been added.
Usage example::
opts = Variables()
opts.Add(
PathVariable(
'qtdir',
help='where the root of Qt is installed',
default=qtdir,
validator=PathIsDir,
)
)
opts.Add(
PathVariable(
'qt_includes',
help='where the Qt includes are installed',
default='$qtdir/includes',
validator=PathIsDirCreate,
)
)
opts.Add(
PathVariable(
'qt_libraries',
help='where the Qt library is installed',
default='$qtdir/lib',
)
)
"""
import os
import os.path
from typing import Callable, Optional, Tuple
import SCons.Errors
import SCons.Util
__all__ = ['PathVariable',]
[docs]class _PathVariableClass:
"""Class implementing path variables.
This class exists mainly to expose the validators without code having
to import the names: they will appear as methods of ``PathVariable``,
a statically created instance of this class, which is placed in
the SConscript namespace.
Instances are callable to produce a suitable variable tuple.
"""
[docs] @staticmethod
def PathAccept(key, val, env) -> None:
"""Validate path with no checking."""
return
[docs] @staticmethod
def PathIsDir(key, val, env) -> None:
"""Validate path is a directory."""
if os.path.isdir(val):
return
if os.path.isfile(val):
msg = f'Directory path for variable {key!r} is a file: {val}'
else:
msg = f'Directory path for variable {key!r} does not exist: {val}'
raise SCons.Errors.UserError(msg)
[docs] @staticmethod
def PathIsDirCreate(key, val, env) -> None:
"""Validate path is a directory, creating if needed."""
if os.path.isdir(val):
return
try:
os.makedirs(val, exist_ok=True)
except FileExistsError as exc:
msg = f'Path for variable {key!r} is a file, not a directory: {val}'
raise SCons.Errors.UserError(msg) from exc
except (PermissionError, OSError) as exc:
msg = f'Path for variable {key!r} could not be created: {val}'
raise SCons.Errors.UserError(msg) from exc
[docs] @staticmethod
def PathIsFile(key, val, env) -> None:
"""Validate path is a file."""
if not os.path.isfile(val):
if os.path.isdir(val):
msg = f'File path for variable {key!r} is a directory: {val}'
else:
msg = f'File path for variable {key!r} does not exist: {val}'
raise SCons.Errors.UserError(msg)
[docs] @staticmethod
def PathExists(key, val, env) -> None:
"""Validate path exists."""
if not os.path.exists(val):
msg = f'Path for variable {key!r} does not exist: {val}'
raise SCons.Errors.UserError(msg)
# lint: W0622: Redefining built-in 'help' (redefined-builtin)
[docs] def __call__(
self, key: str, help: str, default, validator: Optional[Callable] = None
) -> Tuple[str, str, str, Callable, None]:
"""Return a tuple describing a path list SCons Variable.
The input parameters describe a 'path list' variable. Returns
a tuple with the correct converter and validator appended. The
result is usable for input to :meth:`Add`.
The *default* parameter specifies the default path to use if the
user does not specify an override with this variable.
*validator* is a validator, see this file for examples
"""
if validator is None:
validator = self.PathExists
if SCons.Util.is_List(key) or SCons.Util.is_Tuple(key):
helpmsg = f'{help} ( /path/to/{key[0]} )'
else:
helpmsg = f'{help} ( /path/to/{key} )'
return key, helpmsg, default, validator, None
PathVariable = _PathVariableClass()
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