`using` on demand, is it possible?

Ronis_BR · January 16, 2019, 1:23pm

Hi guys!

I have a package that needs to use ODBC.jl for some tasks. However, the compilation time and import time is huge. Hence, I am wondering: is there a way to import packages “on demand”? For example, I just need this package when the user calls the function connect_db.

Gnimuc · January 16, 2019, 2:04pm

Here is the implementation of check_import function in FileIO.jl that provides a similar feature:

github.com

JuliaIO/FileIO.jl/blob/a676a5c51fbc0181ebe46348c63cc6de9e09bcae/src/loadsave.jl#L6-L32


      
          function _findmod(f::Symbol)
              for (u,v) in Base.loaded_modules
                  (Symbol(v) == f) && return u
              end
              nothing
          end
          function topimport(modname)
              @eval Base.__toplevel__  import $modname
              u = _findmod(modname)
              @eval $modname = Base.loaded_modules[$u]
          end
          
          
function checked_import(pkg::Symbol)
              # kludge for test suite
              if isdefined(Main, pkg)
                  m1 = getfield(Main, pkg)
                  isa(m1, Module) && return m1
              end
              if isdefined(FileIO, pkg)
                  m1 = getfield(FileIO, pkg)

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