FWCore/MessageService/doc/preambleMode.txt - master - githubmirror/cmssw

FWCore/MessageService/doc/preambleMode.txt
46 строк2 KB
Giulio Eulisse
Snapshot of CMSSW_6_2_0_pre8.
26 июн 2013, 18:12
26 июн 2013, 18:12214ab73
	The workings of ELoutput::preambleMode 
	--------------------------------------

(A MessageLogger maintenance document)


preambleMode is a data member of the ELoutput destination class.

Its use is in emitToken:  
void ELoutput::emitToken( const ELstring & s, bool nl )  { ...

The first tokens may be of a header nature, in which
case certain line control and other processing is done.  That is indicated
if preambleMode is true; otherwise the token s is output without further ado.

preambleMode is established in several places.  The key one is in 
  bool ELoutput::log( const edm::ErrorObj & msg )  {...
which sets it true **regardless of incoming value**, does whatever header work
is specified by configuration information, and sets it false before 
emitting the ordinary items in the message string.  

In each ctor, it is also established.  Prior to Sept 2 2010 the code
looked like:

ELoutput::ELoutput( std::ostream & os_ , bool emitAtStart ) {
  if (emitAtStart) {
    bool tprm = preambleMode;
    preambleMode = true;
    emitToken( "\n=================================================", true );
    emitToken( "\nMessage Log File written by MessageLogger service \n" );
    emitToken( "\n=================================================\n", true );
    preambleMode = tprm;
  }

Note that the value used for those emitToken calls is invariably true;
note also that whatever value preambleMode had coming in was preserved, 
only to be wiped out by the first log call.  Therefore, the use of tprm
was unnecessary.  Moreover, it was technically use of an unititialized
data member.

Two possible choices for a fix could have been considered:  Initializing
preambleMode (to true) in the initializer list, or removing the use of
tprm.  Since we are going to the trouble of initializing all the other data
members, as is good coding form, we did the former fix, initializing
preambleMode (to true) in the initializer list for each ctor.  We also
removed the now-completely-superfluous code using tprm.