Let $\mathcal{C}$ be a category internal to (some convenient model for) topological spaces (which I will denote by $\mathsf{Top}$). In the [question](https://mathoverflow.net/questions/414293/what-is-the-right-notion-of-a-functor-from-an-internal-topological-category-to-t) Greg Arone asks:

> What is the correct notion of a topological functor $\mathcal{C} \to \mathsf{Top}$?

In particular, Greg wanted to know about the homotopy theory of such functors.  My questions can be seen as somewhat of a follow-up question. Let $\mathcal{M}$ be a topologically enriched category.

> What is the correct notion of a topological functor $\mathcal{C} \to \mathcal{M}$?

Particular examples I am interested in include (some convenient model for) based topological spaces and spectra. 

I am also interested in understanding the homotopy theory of such functors.

>If, in addition, $\mathcal{M}$ is a topological model category, what do we know about the homotopy theory of topological functors $\mathcal{C} \to \mathcal{M}$? 


----------


I am aware of one definition of such functors in the literature. In ["Derivatives of embedding functors I: the stable case"][1] Arone makes the following definition (Definition 3.1), which I will state only for based spaces, but Arone also defines for spectra.

A functor from a small topological category $\mathcal{C}$ to the category of based spaces consists of the following data:

 1. A ex-space $F$ over the space $ob(\mathcal{C})$ of objects of $\mathcal{C}$, the fiber over $c \in \mathcal{C}$ is what we would usually call $F(c)$.
 2. A fiberwise map of objects over the space $mor(\mathcal{C})$ of morphisms of $\mathcal{C}$
$$
\alpha: s^* (F) \to t^*(F),
$$
where $s^*(F)$ and $t^*(F)$ are the pullbacks of $F$ from $ob(\mathcal{C})$ to $mor(\mathcal{C})$ along the source and the larget maps respectively. 

This data is subject to unicity and composition law conditions, which I leave to the reference. The idea is that when $\mathcal{C}$ is discrete, this precisely recovers the standard definitions.

I'm hopeful that there is some 'slicker' way to define such functors analogous to that of a $\mathsf{Top}$-internal diagram as in Emily's [answer](https://mathoverflow.net/a/414345/117088) to Greg's original question. 

  [1]: https://arxiv.org/pdf/0707.3489.pdf