In this example I faced the problem of copying the code:
void BadExample1() {
if (!Initialize1())
return;
if (!Initialize2()) {
Finalize1();
return;
}
if (!Initialize3()) {
Finalize1();
Finalize2();
return;
}
if (!Initialize4()) {
Finalize1();
Finalize2();
Finalize3();
return;
}
// some code..
Finalize1();
Finalize2();
Finalize3();
Finalize4();
}
Bnd here is a bad code structure. If I have a lot of constructs, the width of the code will be too large, this is also bad:
void BadExample2() {
if (Initialize1()) {
if (Initialize2()) {
if (Initialize3()) {
if (Initialize4()) {
if (Initialize5()) {
// some code..
Finalize5();
}
Finalize4();
}
Finalize3();
}
Finalize2();
}
Finalize1();
}
}
How can I save good code sturcture and solve code copying? Finalize1/2/3 is a API functions and not my program classes. Maybe some STL containers can solve it? Maybe something like that?
void GoodExample() {
if (!Initialize1())
return;
RaiiWrapper<void(*)()> raii_wrapper1([]() {
Finalize1();
});
if (!Initialize2()) {
//Finalize1();
return;
}
RaiiWrapper<void(*)()> raii_wrapper2([]() {
Finalize2();
});
if (!Initialize3()) {
//Finalize1();
//Finalize2();
return;
}
RaiiWrapper<void(*)()> raii_wrapper3([]() {
Finalize3();
});
if (!Initialize4()) {
//Finalize1();
//Finalize2();
//Finalize3();
return;
}
RaiiWrapper<void(*)()> raii_wrapper4([]() {
Finalize4();
});
// some code..
//Finalize1();
//Finalize2();
//Finalize3();
//Finalize4();
}
Why not use real objects?
struct SetupPart1 {
SetupPart1 () { if (!Initialize1() throw std::runtime_error("Part1"); }
~SetupPart1 () { Finalize1(); }
};
and so on for part 2, 3, 4, etc. Now your example looks like this:
void GoodExample() {
try {
SetupPart1 p1;
SetupPart2 p2;
SetupPart3 p3;
SetupPart4 p4;
// some code ...
}
catch { const std::runtime_error &ex ) {
std::cerr << "GoodExample Failed: " << ex.what << std::end;
}
}