--- name: "logbuffer" section: "3bobcat" platform: "linux" package: "libbobcat-dev" version: "4.08.06-1" release: "Debian 10 (Buster)" platforms: ["linux"] url: "https://new.carta.tech/logbuffer" --- # logbuffer(3bobcat) std::streambuf handling log messages ## NAME FBB::LogBuffer - **std::streambuf** handling log messages ## SYNOPSIS **#include \**\ Linking option: *-lbobcat* ## DESCRIPTION **FBB::LogBuffer** is a class derived from **std::streambuf** handling log messages. The stream to log to, timestamps and log-levels can be configured both at construction time and beyond. The **FBB::LogBuffer** may be used to initialize a **std::ostream**. ## NAMESPACE **FBB**\ All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace **FBB**. ## INHERITS FROM **std::streambuf** ## ENUMERATION The enumeration **TimeStamps** is defined in the namespace **FBB** to be used when initializing **FBB::LogBuffer** objects. It has the following values: - o **NOTIMESTAMPS**:\ Log-messages will not have timestamps prepended to them. - o **TIMESTAMPS**:\ Log-messages will have timestamps prepended to them. - o **UTCTIMESTAMPS**:\ Log-messages will have timestamps showing the UTC time prepended to them. ## CONSTRUCTORS - o **LogBuffer(TimeStamps timestamps = TIMESTAMPS,** **bool active = true,** **char const \*delim = " ")**:\ This constructor constructs an **FBB::LogBuffer** object writing its log-messages to **std::cerr**. If the **active** parameter is initialized to **false** no messages will be logged until the buffer’s activity is switched on (see **setActive()** below). The parameter **delim** is inserted immediately beyond the time stamp. If a delimiter is inappropriate, an empty string or a 0-pointer may be specified. When **stamps == FBB::NOTIMESTAMPS** **delim** is ignored. A time stamp consists of the month, the day number of the month and the (local) time of the current message, as usually appearing in messages in */var/log* files. E.g., *Aug 5 13:52:23*. - o **LogBuffer(std::ostream &stream,** **TimeStamps timestamps = TIMESTAMPS,** **bool active = true,** **char const \*delim = " ")**:\ This constructor constructs an **FBB::LogBuffer** object writing its log-messages to the stream used to initialize its **stream** parameter. If the **active** parameter is initialized to **false** no messages will be logged until the buffer’s activity is switched on (see **setActive()** below). The parameter **delim** is inserted immediately beyond the time stamp. If a delimiter is inappropriate, an empty string or a 0-pointer may be specified. When **stamps == FBB::NOTIMESTAMPS delim** is ignored. A time stamp consists of the month, the day number of the month and the (local) time of the current message, as usually appearing in messages in */var/log* files. E.g., *Aug 5 13:52:23*. Copy and move constructors are not available. ## MEMBER FUNCTIONS All members of **std::streambuf** are available, as **FBB::LogBuffer** inherits from this class. - o **int overflow(int c)**:\ This member *overrides* the **std::streambuf** member. It is called by *std::ostream* objects using **OFdStreambuf**. It calls *sync()*, an then it puts the next available character into the buffer. It returns the inserted character. - o **void setActive(bool active)**:\ The member function (de)activates logging. The argument **true** activates logging, the argument **false** deactivates it. - o **void setStream(std::ostream &stream)**:\ This member may be used to switch the stream to log to. It is the responsibility of the programmer to ensure that the external stream remains available for as long as log-messages are inserted into it. - o **void settimestamp(FBB::TimeStamps timestamps,** **char const \*delim = " ")**:\ The member function (de)activates time stamp prepending. Use the value **FBB::TIMESTAMPS** to prepend time stamps, **FBB::NOTIMESTAMPS** suppresses time stamps. A time stamp consists of the month, the day number of the month and the (local) time of the current message, as usually appearing in messages in */var/log* files. E.g., *Aug 5 13:52:23*. The parameter **delim** is inserted immediately beyond the time stamp. If a delimiter is inappropriate, an empty string or a 0-pointer may be specified. When **stamps ==** **FBB::NOTIMESTAMPS delim** is ignored. - o **void setEmpty(bool empty)**:\ This member may be called to ensure that a timestamp is inserted before the next insertion. It is called as **setEmpty(true)** when a newline character (*\\n*) is inserted, ensuring that another timestamp is prepended before the next insertion. - o **int sync()**:\ This member *overrides* the **std::streambuf** member. It writes the buffer to the device associated with the file descriptor, and returns 0. ## PROTECTED MEMBER FUNCTION The member listed in this section implements the tasks of the comparably named virtual function in the class’s private interface. This separates the redefinable interface from the user-interface. The class **LogBuffer** can, in accordance with Liskov’s Substitution Principle, be used as a *std:streambuf*; but it also offers a facility for classes deriving from **LogBuffer**. This facility is listed here. - o **int pSync()**:\ The contents of the **LogBuffer**’s internal buffer is flushed. ## EXAMPLE ``` #include #include #include using namespace std; using namespace FBB; int main() { LogBuffer buffer(cout, FBB::TIMESTAMPS); ostream log(&buffer); log << "This message is written to cout" << nl << setw(16) << ’ ’ << "occupying multiple lines\n"; } ``` ## FILES *bobcat/logbuffer* - defines the class interface ## SEE ALSO [**bobcat**(7)](/bobcat/7.md), [**log**(3bobcat)](/log/3bobcat.md) ## BUGS None Reported. ## DISTRIBUTION FILES - o *bobcat\_4.08.06-x.dsc*: detached signature; - o *bobcat\_4.08.06-x.tar.gz*: source archive; - o *bobcat\_4.08.06-x\_i386.changes*: change log; - o *libbobcat1\_4.08.06-x\_\*.deb*: debian package holding the libraries; - o *libbobcat1-dev\_4.08.06-x\_\*.deb*: debian package holding the libraries, headers and manual pages; - o *http://sourceforge.net/projects/bobcat*: public archive location; ## BOBCAT Bobcat is an acronym of \`Brokken’s Own Base Classes And Templates’. ## COPYRIGHT This is free software, distributed under the terms of the GNU General Public License (GPL). ## AUTHOR Frank B. Brokken (**f.b.brokken@rug.nl**).