This does not make sense as a command if Temp is a function and V is a function space.
You haven’t really provided a reproducible code, so Im not sure what you are attempting here.
XDMFFile supports writing first order Lagrange Spaces, thus, you should create an appropriate function space W, being a scalar/vector/tensor space of first order Lagrange elements (depending on the use case), then make a function w in W, and call w.interpolate(Temp) to transfer Temp into a compatible space.