Importing an mx file into a context

Question

Consider the following simple code which dumps the global context:

var = 5;
DumpSave["test.mx", "Global`"];

Now, in a new notebook, I would like to import var in another context. Trying

Begin["myContext`"]
<< "test.mx"
End[]

does not work because var remains in the global context. Is there a solution?

Thank you.

Answer 1

Using Begin and End won't help, because .mx files are lower-level and the way they are loaded is different from normal packages.

I was about to say that this isn't possible, but here is a hack which seems to work:

ClearAll[loadInContext];
loadInContext[context_String,file_String/;FileExtension[file]==="mx"]:=
    Module[{tag},
        Block[{$NewSymbol=Sow[#1,tag]&},
            With[{created=(If[#1==={},{},First[#1]]&)[Reap[Import[file],tag][[2]]]},
                Scan[(Context[#1]=context)&,created]
            ]
        ]
    ]

You can use this as, for example:

loadInContext["MyContext`", "test.mx"}]

It is based on a rather interesting and little-known feature, that the assignment like

Context[sym] = newContext

will move the symbol (together with the global rules possibly attached to it) to a new context.