[petsc-dev] Reminder: *every* symbol with extern linkage *must* be namespaced

[Mark F. Adams]

I am looking for prescriptions.  Several of my problems are local functions, I guess I can make these static (I assume this works for functions).  I made some attempt to name space some of these (gamg_setup_events) and others are tools that need to be global (createSimpleGraph)  -- how should I fix these?  PetscCreateSimpleGraph?


On Mar 17, 2012, at 12:01 PM, Jed Brown wrote:

> On Sat, Mar 17, 2012 at 10:49, Shri <abhyshr at mcs.anl.gov> wrote:
> I don't know namespacing but looks like its a C++ declaration that can be simulated in C either using prefixes or by using a struct.
> http://ejrh.wordpress.com/2012/01/24/namespaces-in-c/ . 
> What's the prefered PETSc way of namespacing in C? Use the prefix 'Petsc'?
> 
> Yes, use prefixes for all symbols with extern linkage. (Whichever prefix is appropriate for the class you are working with.)
> 
> If you have symbols that go togother, and especially if it might make sense to have multiple instances, it makes sense to put them together in a struct. There may still be a global instance of the struct (which must itself be namespaced), but the members of the struct no longer need their own namespace because they are not symbols (in the linker sense).
> 
> Any time you create a symbol with extern linkage, you are declaring that nobody in the universe (defined by all code that might ever be linked into an application that somehow calls PETSc) will ever choose that name for themselves. PETSc already has (in my opinion) claimed more than its share in user-visible namespace (e.g. Vec and Mat), but changing that is obnoxious for users so it has been postponed indefinitely. There is no excuse, however, for not namespacing new symbols or symbols that are not public (intended for the user to interact with).

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