monty.tempfile — monty 4.0.2 documentation

# Source code for monty.tempfile

    """
    Temporary directory and file creation utilities.
    """

    import os
    import tempfile

    from pathlib import Path

    from monty.shutil import copy_r, remove

    class ScratchDir:
        """
        .. note::

            With effect from Python 3.2, tempfile.TemporaryDirectory already
            implements much of the functionality of ScratchDir. However, it does
            not provide options for copying of files to and from (though it is
            possible to do this with other methods provided by shutil).

        Creates a "with" context manager that automatically handles creation of
        temporary directories (utilizing Python's build in temp directory
        functions) and cleanup when done. This improves on Python's built in
        functions by allowing for truly temporary workspace that are deleted
        when it is done. The way it works is as follows:

        1. Create a temp dir in specified root path.
        2. Optionally copy input files from current directory to temp dir.
        3. Change to temp dir.
        4. User performs specified operations.
        5. Optionally copy generated output files back to original directory.
        6. Change back to original directory.
        7. Delete temp dir.
        """
        SCR_LINK = "scratch_link"

        def __init__(self, rootpath, create_symbolic_link=False,
                     copy_from_current_on_enter=False,
                     copy_to_current_on_exit=False):
            """
            Initializes scratch directory given a **root** path. There is no need
            to try to create unique directory names. The code will generate a
            temporary sub directory in the rootpath. The way to use this is using a
            with context manager. Example::

                with ScratchDir("/scratch"):
                    do_something()

            If the root path does not exist or is None, this will function as a
            simple pass through, i.e., nothing happens.

            Args:
                rootpath (str/Path): Path in which to create temp subdirectories.
                    If this is None, no temp directories will be created and
                    this will just be a simple pass through.
                create_symbolic_link (bool): Whether to create a symbolic link in
                    the current working directory to the scratch directory
                    created.
                copy_from_current_on_enter (bool): Whether to copy all files from
                    the current directory (recursively) to the temp dir at the
                    start, e.g., if input files are needed for performing some
                    actions. Defaults to False.
                copy_to_current_on_exit (bool): Whether to copy files from the
                    scratch to the current directory (recursively) at the end. E
                    .g., if output files are generated during the operation.
                    Defaults to False.
            """
            if Path is not None and isinstance(rootpath, Path):
                rootpath = str(rootpath)

            self.rootpath = os.path.abspath(rootpath) if rootpath is not None \
                else None
            self.cwd = os.getcwd()
            self.create_symbolic_link = create_symbolic_link
            self.start_copy = copy_from_current_on_enter
            self.end_copy = copy_to_current_on_exit

        def __enter__(self):
            tempdir = self.cwd
            if self.rootpath is not None and os.path.exists(self.rootpath):
                tempdir = tempfile.mkdtemp(dir=self.rootpath)
                self.tempdir = os.path.abspath(tempdir)
                if self.start_copy:
                    copy_r(".", tempdir)
                if self.create_symbolic_link:
                    os.symlink(tempdir, ScratchDir.SCR_LINK)
                os.chdir(tempdir)
            return tempdir

        def __exit__(self, exc_type, exc_val, exc_tb):
            if self.rootpath is not None and os.path.exists(self.rootpath):
                if self.end_copy:
                    files = set(os.listdir(self.tempdir))
                    orig_files = set(os.listdir(self.cwd))

                    # First copy files over
                    copy_r(self.tempdir, self.cwd)

                    # Delete any files that are now gone
                    for f in orig_files - files:
                        fpath = os.path.join(self.cwd, f)
                        remove(fpath)

                os.chdir(self.cwd)
                remove(self.tempdir)