🚀 go-pugleaf

In article <4gsa2r$gjm@sdaw04.seinf.abb.se>, alindbac@sw.seisy.abb.se wrote:

<< In article <4gognf$et@news.bridge.net>,
<< David Byrden  <100101.2547@compuserve.com> wrote:
<< ><<<<<<<
<< >
<< >Why is it not allowed to delegate the initialisation to another
<< >constructor
<< >
<< >class X
<< >{
<< >public:
<< >    X (int i) : i_(i) {}
<< >
<< >    X () : X(34) {}             // Not allowed
<< >>>>>>>>>>
<< >
<< >
<< >     Why not use      X (int i = 34 ) : i_(i) {}
<< 
<< >[ I think he was concerned with the more general case of a complicated
<< >  initialization (not assignment) that must be repeated for each
<< >  constructor. -sdc, moderator
<< >]
<< 
<< Well, one could use a similar thing using a member function:
<< 
<< X (int i) { init(i); }
<< X () { init(34); }
<< 
<< where init is a member function for class X.
<< 

Not very useful for const or reference data members ( here, useful ==
can't be done without explicitly initializing them, but than you "init"
will do only half the work )

My inclination, although I rarly use const or reference data members, will
be to wrap those data members in an internal structure with it's own
constructor :

class A_Class_With_A_Const_Or_Refs {
    A_Class_With_A_Const_Or_Refs(long& l);
    struct internal_Data {
        long& mLong;
        const long mClassID; // when there was no RTTI, for instance
        internal_Data(long& inLong, const long inID);
        } mInternalData;
    };

A_Class_With_A_Const_Or_Refs::A_Class_With_A_Const_Or_Refs(long& l) :
mInternalData(l, 'MYID') {}

and so on.

In my opinion, those cases will be very rare.

-- 
-- Etay Bogner
-- Etay_Bogner@mail.stil.scitex.com
-- Scitex Corp.
-- Israel.
-- 
-- There are two rules for success in life:                   
-- Rule 1:  Don't tell people everything you know.                
-- 
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