CODEWITHSUNDEEP
c++constructor
Tiana987642
Tiana987642

Reputation: 754

Handle condtional parameter for constructor

My program works this way: if the user inputs the data path parameter, it will use that path. If not, it uses the current path of the program.

The constructor is Server(QString path).

Obviously, this won't work:

if(!isDefaultPath)
   Server server(userPath);
else
   Server server(programPath);
server.doSmth();

Currently, I do like this 

Server serverDefault(programPath);
Server serverCustomized(userPath);
if(!isDefaultPath)
       serverCustomized.doSmth();
    else
       serverDefault.doSmth();

But I feel this ain't nice. Are there any better ways to do this?

Upvotes: 0

Views: 35

Answers (2)

Petr
Petr

Reputation: 10007

The most obvious way is 

Server server(isDefaultPath? programPath : userPath )

Note also that even if you have a more advanced logic that does not fit into a simple ?: operator, you can always implement it to find the needed parameter as string and only then initialize the constructor:

path = programPath;
if (....) path = ...
else ...
path = path + ...;

Server server(path);

One more approach if the constructor calls are drastically different, use a pointer

std::unique_ptr pServer;
if (...) pServer = std::make_unique<Server>(new Server("a", "b"));
else pServer = std::make_unique<Server>(new Server(137));
Server server = *pServer;
...

Upvotes: 5

Jarod42
Jarod42

Reputation: 218238

You may use ternary operator:

Server server(isDefaultPath ? programPath : userPath);

Upvotes: 2

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