Reusing variables declared on Try-Catch

Question

I am using a try-catch block like this one:

try {

    Texture heightmapTexture = Texture("Snow0101_7_M.jpg");

} catch (TextureLoadException exc) {
    std::cout << exc.what() << std::endl;
}

The thing is that I need to reuse the variable heightmapTexture further in my program. So I realized I can't do that because of the scope. Should I put the rest of the program inside the scope? For me that doesn't make any sense.

I also can't declare the variable outside of the scope because I have to initialize it. It has a constructor that only receives a string as input.

What would be the best solution?

I realize that I could use a pointer, but I am trying to avoid that (I am not really good at preventing memory leaks).

EDIT: Sorry, I was declaring the variable as a class Heightmap, which is wrong!, it is a texture object. But the problem is the same.

Use a boost::shared_ptr instead of raw pointers, will avoid leaks and will solve the problem. — vishal129, Dec 05 '14 at 19:03
An object that can be initialized but not assigned? Can you change that class? — Silicomancer, Dec 05 '14 at 19:08
what do you mean @Silicomancer? I guess it will have to be a pointer then. — lhahn, Dec 05 '14 at 19:09
You could add a default constructor and an assignment operator to Heightmap it so you can first define an empty object (before try) and then assign the texture in the try block. BTW *why* do you want to reuse the object? — Silicomancer, Dec 05 '14 at 19:17
Ahm, the object has to methods of Binding and Unbinding the texture. — lhahn, Dec 05 '14 at 19:20

score 2 · Accepted Answer · answered Dec 05 '14 at 19:15

you'd normally want all your logic inside one try/catch context. Presumably if the loading of a texture fails, everything after it will fail also?

in which case you might be able to express the logic more neatly as:

try {
    Heightmap heightmapTexture = Texture("Snow0101_7_M.jpg");

    // do your work here

    // if anything fails fatally, throw

    // do you need to store the height map in an object?
    my_object.give_heightmap(std::move(heightmapTexture));
} 
// report failures here
catch (TextureLoadException& exc) { // note: by reference
    std::cout << exc.what() << std::endl;
}
catch (OtherReason& e) {
    // report the reason
}
catch(exception& e) {
  // other failures
}

A good way to think about exception handling is that an exception object is the explanation you are being given for a process or sequence failing, rather than each exception being an error code for one operation.

score 0 · Answer 2 · answered Dec 05 '14 at 19:06

0

Declare your variable outside of the try-catch block like so.

Heightmap *heightmapTexture = null;

try {

    heightmapTexture = new Texture("Snow0101_7_M.jpg");

} catch (TextureLoadException exc) {
    std::cout << exc.what() << std::endl;
}

answered Dec 05 '14 at 19:06

user4330016

1

I can't do that in c++ – lhahn Dec 05 '14 at 19:08
1

no! Firstly, this requires Heightmap to have a default constructor. Secondly it defeats the purpose of exception handling. – Richard Hodges Dec 05 '14 at 19:09
1

raw pointers are evil. do not use – Richard Hodges Dec 05 '14 at 19:13
@RichardHodges no default constructor is required here – M.M Aug 02 '18 at 12:14

Reusing variables declared on Try-Catch

2 Answers2