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Subject: Re: [boost] [optional] generates unnessesary code for trivial types
From: Krzysztof Czainski (1czajnik_at_[hidden])
Date: 2012-02-14 13:48:35

+1 for optional<T&> with the current assignment semantics and optimization.

In my opinion, optional<T&> is better then T*, because:
- it is clear, that the object isn't owned (owning T* pointers should be
replaced by smart pointers, but that's another story);
- the default constructor of optional<T&> initializes it to none;
- it is clear, that the object actually is optional, whereas with T*, it
needs to be documented "can be null" or something;
- I don't have to write my own get_value_or function, no matter how trivial
it would be for pointers ;-) ;
- access is asserted, so logic errors are caught early (right?).

Also, I prefer optional<T&> to some dumb_ptr, because optional<T&> says
exactly what i mean, and dumb_ptr - not really.

A note about assignment semantics:
int i = 1, j = 2;
optional<int&> oi = i, oj = j;
oi = oj;
If many people find it confusing, that oi now contains a reference to j,
while i remains unchanged, I could live with this kind of assignment
disabled at compile-time, and replaced by some member function. But
personally I prefer to leave those semantics unchanged.

A note about optimization: as it has been said, it seems easier to just
provide the optimization, than discuss it over and over again.


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