# FBB::Mbuf(3bobcat)

## Message handler
(libbobcat-dev_5.07.03)

## 2005-2021

## NAME

FBB::Mbuf - std::streambuf handling messages

## SYNOPSIS

#include <bobcat/mbuf>
Linking option: -lbobcat

## DESCRIPTION

Objects of this class are derived from std::streambuf, and are used to handle messages in a standardized way. Messages may be prefixed with order (line) numbers and/or labels.

By default all messages are inserted into the standard output stream, but other destinations (standard error, a named file, etc.) can easily be configured.

FBB::Mbuf objects themselves are std::streambuf objects, so they can be used to construct std::ostream objects. However, they are intended to be used by mstream(3bobcat) objects, and passing Mbuf objects to other kind of ostream objects is deprecated and results in undefined behavior.

## NAMESPACE

FBB
All elements mentioned in this man-page, are defined in the namespace FBB.

## INHERITS FROM

std::streambuf

## CONSTRUCTORS

- Mbuf():
  The default constructor handles messages using the std::streambuf also used by std::cout. There is no limit to the number of messages that may be inserted. No message or line numbers are shown, no exception are thrown when inserting messages.
- explicit Mbuf(std::streambuf *buf, size_t maxCount = std::numeric_limits<size_t>::max(), std::string const &tag = "", bool throwing = false):
  This constructor uses buf to handle messages. By default (using the default argument values) there is no limit to the number of messages that may be inserted. No message or line numbers are shown, no exception are thrown when inserting messages. Specifying any other value than std::numeric_limits<size_t>::max() sets the maximum number of messages that can be inserted to that value. The tag defines the text of the message label (e.g., Error). When throwing is specified as true an FBB::Exception exception is thrown after completing a message. The generated exception holds the id (see below for the member id) of the FBB::Mbuf object from which the exception was thrown as well as the text FBB::Mbuf.
- explicit Mbuf(std::string const &name, size_t maxCount = std::numeric_limits<size_t>::max(), std::string const &tag = "", bool throwing = false):
  This constructor creates a std::ofstream from the provided name parameter that receives the messages handled by the constructed FBB:Mbuf object. It throws an FBB::Exception exception if the stream cannot be opened for writing. If a file by that name already exists it is rewritten. The remaining parameters are identical to those of the previous two constructors.

Copy and move constructors (and assignment operators) are not available.

## MEMBER FUNCTIONS

- size_t count() const:
  returns the number of inserted messages (if setCount has been called: the value set by the last setCount call plus the number of inserted messages since that call).

- bool lineExcess() const:
  returns true after attempting to insert an additional message after maxCount() number of messages have been inserted.

- std::string const &lineTag() const:
  returns the currently used line-tag (by default `Line').

- size_t maxCount() const:
  returns the maximum number of messages that can be inserted. If the returned value equals std::numeric_limits<size_t>::max() then there is no limit to the number of messages that can be inserted.

- void noLineNr():
  calling this member will suppress the display of a line number if it is called after calling setLineNr (see below) but before a message is being (or has been) inserted.

- void reset(std::streambuf *buf, size_t maxCount, std::string const &tag, bool throwing):
  messages inserted into FBB::Mbuf objects are handled by std::streambuf buf. By specifying std::numeric_limits<size_t>::max() for maxCount there is no limit to the number of messages that may be handled by this std::streambuf. The tag defines the text of the message label (e.g., Error or the empty string for no message label). When throwing is specified as true an FBB::Exception exception is thrown after completing a message.

- void reset(std::string const &name, size_t maxCount, std::string const &tag, bool throwing):
  messages inserted into FBB::Mbuf objects are handled by a std::ofstream created using the provided name parameter. It throws an FBB::Exception exception if the stream cannot be opened for writing. If a file by that name already exists it is rewritten. The remaining parameters are identical to those of the previous reset members.

- void reset(FBB::Mbuf const &mbuf):
  the current object is reset using the parameters of the mbuf parameter. Following the reset all of the current object's parameters can independently be modified from those used by mbuf.

- void setCount(size_t count):
  assigns the value count to the object's message counter.

- void setLineNr(size_t lineNr):
  specifies the value lineNr as the message's line number when the next line is displayed (see also noLineNr). This value is not changed by the FBB::Mbuf object. To display another line number the member will have to be called again (i.e., the line number is not displayed automatically again at every new line).

- void setLineTag(std::string const &tag):
  specifies the tag prefixing line numbers. By default the line tag equals `Line'.

- void setMaxCount(size_t maxCount):
  defines maxCount as the maximum number of messages that can be inserted into the FBB::Mbuf object.

- void setTag(std::string const &tag):
  specifies the tag prefixing messages. By default the tag is empty. If not empty the tag is enclosed by square brackets. E.g., specifying the tag `Error' will prefix messages with [Error].

- std::string const &tag() const:
  returns the currently used message tag (by default an empty string).

- bool throws():
  returns true when the FBB::Mbuf object will throw an FBB::Exception exception at the next completed message. The generated exception holds the id (see earlier for the member id) of the FBB::Mbuf object from which the exception was thrown as well as the text FBB::Mbuf.

- void throwing(bool ifTrue):
  modifies the behavior of FBB::Mbuf objects at completed messages. After passing true FBB::Mbuf objects will throw an FBB::Exception exception at the next completed message, otherwise this exception is not thrown.

## EXAMPLE

See the mstream(3bobcat) example.

## FILES

bobcat/mbuf - defines the class interface

## SEE ALSO

bobcat(7), exception(3bobcat), mstream(3bobcat)

## BUGS

None Reported.

## BOBCAT PROJECT FILES

- https://fbb-git.gitlab.io/bobcat/: gitlab project page;
- bobcat_5.07.03-x.dsc: detached signature;
- bobcat_5.07.03-x.tar.gz: source archive;
- bobcat_5.07.03-x_i386.changes: change log;
- libbobcat1_5.07.03-x_*.deb: debian package containing the libraries;
- libbobcat1-dev_5.07.03-x_*.deb: debian package containing the libraries, headers and manual pages;

## 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).