Static and global constructors

[Richard Hayden]

Hi,

I'm wondering if there is any order in the calling of global and static
member objects' constructors which occurs before a C++ program can run.
For example, what if I wish to use static member variable objects in a
global variable's constructor? I was thinking that perhaps C++
guarantees to construct all global variable objects first or all static
member variable objects first. Is this at all the case?

Thanks,

Richard Hayden.

 

[Gregg]

Hi,

I'm wondering if there is any order in the calling of global and static
member objects' constructors which occurs before a C++ program can run.
For example, what if I wish to use static member variable objects in a
global variable's constructor? I was thinking that perhaps C++
guarantees to construct all global variable objects first or all static
member variable objects first. Is this at all the case?

Thanks,

Richard Hayden.

Statics are constructed in the order in which they appear in each
translation unit (single compiled file and what it #includes). Order of
initialization between translation units is implementation defined. If
you need to be able to use global objects across translation units, you
either have to use a trick like "nifty counter" (google to find out what
it is) or use a singleton object that creates it on demand.

Gregg


Gregg

 

[Gregg]

Statics are constructed in the order in which they appear in each

By "order in which they appear", I meant "order in which the objects are
defined". The order they are declared is immaterial to construction order.

Gregg

 

[Pete Becker]

Order of
initialization between translation units is implementation defined.

It's unspecified, not implementation defined.

 

[Gregg]

It's unspecified, not implementation defined.

What's the difference? Isn't a given implementation deterministic in this
regard?

Gregg

 

[Pete Becker]

What's the difference? Isn't a given implementation deterministic in this
regard?

The difference is that implementation defined means that a conforming
implementation must document what it does. Yes, it's deterministic, but
typically far too complex for anyone to want to try to figure out.
Objects in libraries are only linked when the linker determines that
they're needed; sometimes that requires multiple passes through the list
of libraries.