- previous support for file appending (largely unused) always
specified opening with the std::ios_base::app flag.
Now differentiate between append behaviours:
APPEND_APP
~~~~~~~~~~
Corresponds to std::ios_base::app behaviour:
- Existing files will be preserved and a seek-to-end is performed at
every write. With this mode seeks/repositioning within the file
will effectively be ignored on output.
APPEND_ATE
~~~~~~~~~~
Largely approximates std::ios_base::ate behaviour:
- Existing files will be preserved and a seek-to-end is performed
immediately after opening, but not subsequently. Can use seekp()
to overwrite parts of a file.
- with ATOMIC, an intermediary file is created - eg, (fileAbc~tmp~)
where all of the output is written to. When the stream goes out of
scope, this intermediary file is moved/renamed to the actually
output name - eg, (fileAbc~tmp~) -> (fileAbc).
This adds some safety if the simulation crashes while writing the
file, since it will the partial (corrupt) file will be left
behind as (fileAbc~tmp~) and not as (fileAbc), which means it will
will be treated as a backup file and not loaded again on restart.
ENH: provided enumeration for APPEND/NON_APPEND
- clearer than using bool (with comments).
Since append mode is primarily only used by masterOFstream etc
this change is unlikely to affect user coding.
ENH: use file atomic for ensight file creation
- avoids corrupt (truncated) files being referenced by the ensight
case file if the simulation crashes while writing the ensight file.
