LoadpackageAndExposeGlobals

pkg/GAPJulia/JuliaInterface/julia/gap.jl

@@ -94,3 +94,66 @@ macro gap(str)
 end
 
 export @gap
+
+"""
+    LoadPackageAndExposeGlobals(package::String, mod::String; all_globals::Bool = false)
+    LoadPackageAndExposeGlobals(package::String, mod::Module = Main; all_globals::Bool = false)
+
+`LoadPackageAndExposeGlobals` loads `package` into GAP via `LoadPackage`,
+and stores all newly defined GAP globals as globals in the module `mod`. If `mod` is
+a string, the function creates a new module, if `mod` is a Module, it uses `mod` directly.
+
+The function is intended to be used for creating mock modules for GAP packages.
+If you load the package `CAP` via
+
+    LoadPackageAndExposeGlobals( "CAP", "CAP" )
+
+you can use CAP commands via
+
+    CAP.PreCompose( a, b )
+
+"""
+function LoadPackageAndExposeGlobals(package::String, mod::String; all_globals::Bool = false)
+    mod_sym = Symbol(mod)
+    Base.MainInclude.eval(:(
+        module $(mod_sym)
+            import GAP
+        end
+    ))
+    ## Adds the new module to the Main module, so it is directly accessible in the julia REPL
+    mod_mod = Base.MainInclude.eval(:(Main.$(mod_sym)))
+
+    ## We need to call `invokelatest` as the module `mod_mod` was only created during the
+    ## call of this function in a different module, so its world age is higher than the
+    ## function calls world age.
+    Base.invokelatest(LoadPackageAndExposeGlobals, package, mod_mod; all_globals = all_globals)
+end
+
+function LoadPackageAndExposeGlobals(package::String, mod::Module; all_globals::Bool = false)
+    current_gvar_list = nothing
+    if !all_globals
+        current_gvar_list = Globals.ShallowCopy(Globals.NamesGVars())
+    end
+    load_package = EvalString("LoadPackage(\"$package\")")
+    if load_package == Globals.fail
+        error("cannot load package $package")
+    end
+    new_gvar_list = nothing
+    if all_globals
+        new_gvar_list = Globals.NamesGVars()
+    else
+        new_gvar_list = Globals.Difference(Globals.NamesGVars(),current_gvar_list)
+    end
+    new_symbols = gap_to_julia(Array{Symbol,1},new_gvar_list)
+    for sym in new_symbols
+        try
+            mod.eval(:(
+                $(sym)=GAP.Globals.$(sym)
+            ))
+        catch
+        end
+    end
+end
+
+export LoadPackageAndExposeGlobals
+