File Access

h5pp offers more flags for file access permissions than HDF5. The new flags are primarily intended to prevent accidental loss of data, but also to clarify intent and avoid mutually exclusive options.

The flags are listed in the order of increasing "danger" that they pose to previously existing files.

Flag	File exists	No file exists	Comment
READONLY	Open with read-only access	Throw error	Never writes to disk, fails if the file is not found
COLLISION_FAIL	Throw error	Create new file	Never deletes existing files and fails if it already exists
RENAME (default)	Create renamed file	Create new file	Never deletes existing files. Invents a new filename to avoid collision by appending "-#" (#=1,2,3...) to the stem of the filename
READWRITE	Open with read-write access	Create new file	Never deletes existing files, but is allowed to open/modify
BACKUP	Rename existing file and create new	Create new file	Avoids collision by backing up the existing file, appending ".bak_#" (#=1,2,3...) to the filename
REPLACE	Truncate (overwrite)	Create new file	Deletes the existing file and creates a new one in place

• When a new file is created, the intermediate directories are always created automatically.
• When a new file is created, READWRITE access to it is implied.

To give a concrete example, the syntax works as follows

    h5pp::File file("somePath/someFile.h5", h5pp::FileAccess::REPLACE);