File valuefd.py#

File List > build > lib.linux-armv7l-cpython-311 > pypisoundmicro > valuefd.py
import os
from .swig import pypisoundmicro as psm
from ._utils import copy_doc
from typing import Union

@copy_doc(psm.ValueFd)
class ValueFd:
    """A wrapper around a file descriptor for reading/writing element values."""
    _fd_obj: psm.ValueFd = None

    def __init__(self, fd: Union[psm.ValueFd, int]):
        """Create a ValueFd from an existing file descriptor.

        Args:
            fd (int): The file descriptor to wrap
        """
        if isinstance(fd, psm.ValueFd):
            self._fd_obj = fd
        elif isinstance(fd, int):
            self._fd_obj = psm.ValueFd(fd)
        else:
            raise TypeError('fd must be a psm.ValueFd or an int')

    def __del__(self):
        """Close the file descriptor when the object is garbage collected."""
        self.closeclose()

    @property
    def is_valid(self) -> bool:
        """ Returns true if the object holds a valid fd."""
        return self._fd_obj.isValid() if self._fd_obj else False

    def take(self) -> int:
        """ Returns the fd value, and won't close it in the destructor, transferring ownership."""
        if self._fd_obj is None:
            return -1
        fd = self._fd_obj.take()
        self._fd_obj = None
        return fd

    def get(self) -> int:
        """ Returns the fd value for your use, but keeps ownership, and will close it upon destruction."""
        return self._fd_obj.get() if self._fd_obj else -1

    def close(self) -> None:
        """ Closes the fd and forgets about it."""
        if hasattr(self, '_fd_obj') and self._fd_obj is not None:
            err = self._fd_obj.close()
            if err != 0:
                raise OSError(f'Failed to close file descriptor: {err}')
            self._fd_obj = None

    def write(self, value) -> int:
        """ Outputs a decimal number to the fd."""
        return self._fd_obj.write(value) if self._fd_obj else -1

    def read(self) -> int:
        """
        Reads a decimal number from the fd and returns it as integer.

        :raises OSError: If the file descriptor is invalid or if an error occurs during reading.
        :return: The read value.
        """
        if self._fd_obj is None:
            return (-1, os.EBADF)
        result, err = self._fd_obj.read()
        if err != 0:
            raise OSError(f'Failed to read from file descriptor: {err}')
        return result