Microsoft.VisualStudio.Project.NestedProjectNode.InitializeInstanceGuid C# (CSharp) Method

        protected virtual void InitializeInstanceGuid()
        {
            if (this.projectInstanceGuid != Guid.Empty)
            {
                return;
            }

            Guid instanceGuid = Guid.Empty;

            Debug.Assert(this.nestedHierarchy != null, "The nested hierarchy object must be created before calling this method");

            // This method should be called from the open children method, then we can safely use the IsNewProject property
            if (this.ProjectManager.IsNewProject)
            {
                instanceGuid = Guid.NewGuid();
                this.ItemNode.SetMetadata(ProjectFileConstants.InstanceGuid, instanceGuid.ToString("B"));
                ErrorHandler.ThrowOnFailure(this.nestedHierarchy.SetGuidProperty(VSConstants.VSITEMID_ROOT, (int)__VSHPROPID.VSHPROPID_ProjectIDGuid, ref instanceGuid));
            }
            else
            {
                // Get a guid from the nested hierarchy.
                Guid nestedHiererachyInstanceGuid;
                ErrorHandler.ThrowOnFailure(this.nestedHierarchy.GetGuidProperty(VSConstants.VSITEMID_ROOT, (int)__VSHPROPID.VSHPROPID_ProjectIDGuid, out nestedHiererachyInstanceGuid));

                // Get instance guid from the project file. If it does not exist then we create one.
                string instanceGuidAsString = this.ItemNode.GetMetadata(ProjectFileConstants.InstanceGuid);

                // 1. nestedHiererachyInstanceGuid is empty and instanceGuidAsString is empty then create a new one.
                // 2. nestedHiererachyInstanceGuid is empty and instanceGuidAsString not empty use instanceGuidAsString and update the nested project object by calling SetGuidProperty.
                // 3. nestedHiererachyInstanceGuid is not empty instanceGuidAsString is empty then use nestedHiererachyInstanceGuid and update the outer project element.
                // 4. nestedHiererachyInstanceGuid is not empty instanceGuidAsString is empty then use nestedHiererachyInstanceGuid and update the outer project element.

                if (nestedHiererachyInstanceGuid == Guid.Empty && String.IsNullOrEmpty(instanceGuidAsString))
                {
                    instanceGuid = Guid.NewGuid();
                }
                else if (nestedHiererachyInstanceGuid == Guid.Empty && !String.IsNullOrEmpty(instanceGuidAsString))
                {
                    instanceGuid = new Guid(instanceGuidAsString);

                    ErrorHandler.ThrowOnFailure(this.nestedHierarchy.SetGuidProperty(VSConstants.VSITEMID_ROOT, (int)__VSHPROPID.VSHPROPID_ProjectIDGuid, ref instanceGuid));
                }
                else if (nestedHiererachyInstanceGuid != Guid.Empty)
                {
                    instanceGuid = nestedHiererachyInstanceGuid;

                    // If the instanceGuidAsString is empty then creating a guid out of it would throw an exception.
                    if (String.IsNullOrEmpty(instanceGuidAsString) || nestedHiererachyInstanceGuid != new Guid(instanceGuidAsString))
                    {
                        this.ItemNode.SetMetadata(ProjectFileConstants.InstanceGuid, instanceGuid.ToString("B"));
                    }
                }
            }

            this.projectInstanceGuid = instanceGuid;
        }