How do I reload a module in an active Julia session after an edit?

Question

2018 Update: Be sure to check all the responses, as the answer to this question has changed multiple times over the years. At the time of this update, the Revise.jl answer is probably the best solution.

I have a file "/SomeAbsolutePath/ctbTestModule.jl", the contents of which are:

module ctbTestModule
export f1
f1(x) = x + 1
end

I fire up Julia in a terminal, which runs "~/.juliarc.jl". The startup code includes the line:

push!(LOAD_PATH, "/SomeAbsolutePath/")

Hence I can immediately type into the Julia console:

using ctbTestModule

to load my module. As expected f1(1) returns 2. Now I suddenly decide I want to edit f1. I open up "/SomeAbsolutePath/ctbTestModule.jl" in an editor, and change the contents to:

module ctbTestModule
export f1
f1(x) = x + 2
end

I now try to reload the module in my active Julia session. I try

using ctbTestModule

but f1(1) still returns 2. Next I try:

reload("ctbTestModule")

as suggested here, but f1(1) still returns 2. Finally, I try:

include("/SomeAbsolutePath/ctbTestModule.jl")

as suggested here, which is not ideal since I have to type out the full absolute path since the current directory might not be "/SomeAbsolutePath". I get the warning message Warning: replacing module ctbTestModule which sounds promising, but f1(1) still returns 2.

If I close the current Julia session, start a new one, and type in using ctbTestModule, I now get the desired behaviour, i.e. f1(1) returns 3. But obviously I want to do this without re-starting Julia.

So, what am I doing wrong?

Other details: Julia v0.2 on Ubuntu 14.04.

Thank you for including the 2018 update. Simply because it's been so long since workspace() existed in Julia, I'd go so far as to accept miguelmorin's answer now instead of the previously accepted answer that has since become deprecated. — NoseKnowsAll
@NoseKnowsAll Honestly, I'm not sure what the appropriate etiquette is in this situation. The accepted answer does not necessarily need to be the right one. Rather the FAQ states that it is the one the asker found most helpful. For me, this is the currently accepted answer. Given my 2018 update at the top of my post directs readers in the right direction, I think it is better to just leave things be. — Colin T Bowers

waTeim waTeim · Accepted Answer · 2014-08-01T10:04:56

The basis of this problem is the confluence of reloading a module, but not being able to redefine a thing in the module Main (see the documentation here) -- that is at least until the new function workspace() was made available on July 13 2014. Recent versions of the 0.3 pre-release should have it.

Before workspace()

Consider the following simplistic module

module TstMod
export f

function f()
   return 1
end

end

Then use it....

julia> using TstMod

julia> f()
1

If the function f() is changed to return 2 and the module is reloaded, f is in fact updated. But not redefined in module Main.

julia> reload("TstMod")
Warning: replacing module TstMod

julia> TstMod.f()
2

julia> f()
1

The following warnings make the problem clear

julia> using TstMod
Warning: using TstMod.f in module Main conflicts with an existing identifier.

julia> using TstMod.f
Warning: ignoring conflicting import of TstMod.f into Main

Using workspace()

However, the new function workspace() clears Main preparing it for reloading TstMod

julia> workspace()

julia> reload("TstMod")

julia> using TstMod

julia> f()
2

Also, the previous Main is stored as LastMain

julia> whos()
Base                          Module
Core                          Module
LastMain                      Module
Main                          Module
TstMod                        Module
ans                           Nothing

julia> LastMain.f()
1

How do I reload a module in an active Julia session after an edit?

5 Answers

Before workspace()

Using workspace()