initializing an auto type variable to zero. Is this type safe?

Question

I'm relatively new to using the auto type, but I have been seeing it a lot in my code base at work lately. One of the reasons I don't like using it is because I often forward declare things, which as far as I know cannot be done with auto. I was under the impression this was because types are determined at compile time.

What I am seeing a lot of is this, and I don't understand why you would ever do it.

auto value = 0;
if ( condition 1 )
{
    value = mValueStore.getValue(foo::bar::value);
}
else
{
    value = mValueStore.getValue(foo::bar::value2);
}

Is there a justification for doing this?

Answer 1

Either using auto or int in this case is not perfect - because type of value is "disconnected" from the type that method returns. Probably int is little bit better in this case because type of value is clear, with auto it can give wrong impression. Better solution could be:

 decltype(mValueStore.getValue(foo::bar::value)) value = 0;

but that is verbose so even better using auto with conditional operator

 auto value = mValueStore.getValue( condition ? foo::bar::value : foo::bar::value2);

if possible to rewrite expression like that so value would always have the same type as that method returns.