[LLVMdev] ConstantBuilder proposal

[Talin]

On Fri, Feb 4, 2011 at 2:12 PM, Frits van Bommel <fvbommel at gmail.com> wrote:

> If you remove all the 'static's from the member functions, it'd work
> more like IRBuilder.
> It would also allow you to take the LLVMContext& as a constructor
> parameter, so that methods like this:
>
> On Fri, Feb 4, 2011 at 6:57 PM, Talin <viridia at gmail.com> wrote:
> >   /// GetStruct - return a constant struct given a context and a vector
> >   /// of elements.
> >   static Constant *GetStruct(
> >     LLVMContext &Context,
> >     const std::vector<Constant*> &V,
> >     bool Packed = false) {
> >     return ConstantStruct::get(Context, V, Packed);
> >   }
>
> can remove it from their parameter list. It's probably pretty unlikely
> a given ConstantBuilder instance would be used with multiple
> LLVMContexts.
>

I thought about that - the only issue is that the only methods that need a
context parameter are the ones for building structs, the rest can derive the
context from the arguments. (in fact, you could even get the context for the
struct-building methods from the arguments except in the case where the
struct was empty.)

>
> Making this a class you need an instance of would likely also allow
> typing to be reduced a bit because said instance can be given a
> shorter name than 'ConstantBuilder'. For example: 'cb.GetStruct(...)'
> instead of 'ConstantBuilder::GetStruct(MyContext, ...)'.
>

That would make sense if you were going to keep the builder around for
creating more than one constant with the same instance.

In my own code, I have a StructBuilder class that is specialized for
building structs:

   Constant * foo = StructBuilder(context)
     .add(ptr)
     .addNullPtr(type)
     .addInt32(10)
     .build();

-- 
-- Talin
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