[#BloombergLP-ball-FileObserver-enableFileLogging-00]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/ball.adoc[ball]::xref:BloombergLP/ball/FileObserver.adoc[FileObserver]::enableFileLogging
:relfileprefix: ../../../
:mrdocs:

Enable file logging, optionally appending a timestamp to the name.

== Synopsis

Declared in `<ball_fileobserver.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
enableFileLogging(
    char const* logFilenamePattern,
    bool appendTimestampFlag);
----

== Description

Enable logging of all records published to this file observer to a file whose name is derived from the specified `logFilenamePattern` and append a timestamp to the log filename if the specified `appendTimestampFlag` is `true`. Return 0 on success, a positive value if file logging is already enabled (with no effect), and a negative value otherwise. If the `appendTimestampFlag` is `true` and `logFilenamePattern` does not contain any `%`‐escape sequences, this method behaves as if ".%T" is appended to `logFilenamePattern`.

DEPRECATED: Use `enableFileLogging(logFilenamePattern)` instead (use the ".%T" pattern to replicate `true == appendTimestampFlag` behavior).

== Return Value

0 on success, positive if already enabled, negative on error

== Parameters

[cols="1,4"]
|===
| Name| Description
| *logFilenamePattern*
| filename pattern, possibly with `%`‐escapes
| *appendTimestampFlag*
| whether to append a timestamp to the filename
|===


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