  In this paper, we propose a general form of the equation of state (EoS) which
is the function of the fractional dark energy density $\Omega_{d}$. At least,
five related models, the cosmological constant model, the holographic dark
energy model, the agegraphic dark energy model, the modified holographic dark
energy model and the Ricci scalar holographic dark energy model are included in
this form. Furthermore, if we consider proper interactions, the interactive
variants of those models can be included as well. The phase-space analysis
shows that the scaling solutions may exist both in the non-interacting and
interacting cases. And the stability analysis of the system could give out the
attractor solution which could alleviate the coincidence problem.
