Can a cleric "multi class" between domains? [duplicate]

I have a player asking me if there is a mechanic that would allow them to take on a second domain, much in the same way a player can multi class. My gut here is no and I am contemplating instead finding out which 2 domains they wish to combine and then forming my own homebrew deity and domain that takes aspects of each, but not everything. But is there a RAW way that a player could take on multiple domains as a cleric?

Java – IntelliJ claims it can not find "Symbol: class" if the "class" is actually an interface

So I write a simple text encoder for a homework and for some reason IntelliJ refuses to create my project. It is claimed that my "Word" user interface can not be found when I try to create my project. I've seen other people ask a similar question, and their problem has been resolved simply by rebuilding their project. No matter how many times I press "Build -> ReBuild Project", it never fixes the bug. I also tried to restart IntelliJ IDEA, but that does not help. It is also strangely maintained that Word is a class, not an interface.

Error message:

Error:(1, 45) java: cannot find symbol
  symbol: class Word

The error points to the first line of the L33t class code:

class L33t extends WordBehaviors implements Word{

Is it possible to share an "enum class" between C ++ and C #?

I refer to an earlier question: is it possible to share an enum declaration between C # and unmanaged C ++?

I would like to do something similar, but for an enumeration class instead of an enumeration:

C ++ Code:

enum class MyEnum {ONE, TWO, THREE, ...}

C # code:

public listing {ONE, TWO, THREE, ...}

Is there a preprocessor magic that can achieve this? I can not seem to remove the keyword "class" in the C # part of the code.

eg: in MyEnum.cs

#if __LINE__ // if C ++
#define public // C ++ Code: Removes the public keyword for C ++
#define class // does not work: The class keyword for C # can not be removed

enum class MyEnum {ONE, TWO, THREE, ...}

#if __LINE__
#undef public // ok: remove public = nothing definition in C ++
#undef class // does not work: #undef must be in C # at the beginning of the file

dnd 5e – PHB, p. 164: What does "as if you were a single member of this class" mean?

I am currently building a multiclass wizard and came across this discussion:

Can a multi-class wizard copy every spell he finds into his spellbook?

This discussion seems to be hanging on the phrase

as if you were a single member of this class.

from p. 164 of the PHB. What this means, however, is never discussed in relation to RAW. The Twittersphere has produced this tweet, which is referenced by @Cambio in its response to the above thread, but Twitter is not a discussion platform and therefore no justification was found. In addition, tweets are not RAW.

So on my specific questions:

  1. Can a single-class member have higher magic slots than would normally be allowed by a nebulous "spellcaster-level" concept that is independent of the grade level?

  2. Does "as if you were a single member of this class" mean that you determine the spells for individual classes during character development? Or do we work at all points of character development with a consistent set of magic slots? Or both?

  3. Is there any source material for the concept that unified character slots are not a class-dependent concept (eg from commentary)?

    Characters with multiple classes in D & D5 use a unified set of spells, there is no concept for "spell magic slots" for our multiclass wizard.

created by @ Danny Cuppets) outside the implication of the PHB Multiclass spell chart?

I specifically see rules written as this has tickled my logical bone.