saving with bson modifies dict argument

[GregPlowman]

Writing with bson(file, dict) seems to modify the dict argument.
Is this the intended behaviour?

Julia-1.1.0> using BSON

Julia-1.1.0> d = Dict(:a => [1+2im, 3+4im], :b => "Hello, World!")
Dict{Symbol,Any} with 2 entries:
  :a => Complex{Int64}[1+2im, 3+4im]
  :b => "Hello, World!"

Julia-1.1.0> d2 = copy(d)
Dict{Symbol,Any} with 2 entries:
  :a => Complex{Int64}[1+2im, 3+4im]
  :b => "Hello, World!"

Julia-1.1.0> bson("test.bson", d)

Julia-1.1.0> d
Dict{Symbol,Any} with 2 entries:
  :a => Dict{Symbol,Any}(:tag=>"array",:type=>Dict{Symbol,Any}(:tag=>"datatype",:params=>Any[Dict{Symbol,Any}(:tag=>"datatype",:params=>Any[],:name=>Any["Main", "Core", "Int64"])],:name=>Any["Main", …
  :b => "Hello, World!"

Julia-1.1.0> d3 = BSON.load("test.bson")
Dict{Symbol,Any} with 2 entries:
  :a => Complex{Int64}[1+2im, 3+4im]
  :b => "Hello, World!"

Julia-1.1.0> d3 == d
false

Julia-1.1.0> d3 == d2
true

[Datseris]

Hi, this seems to be a big problem for me as I later want to use the dictionaries I save using BSON. Is there a way to solve this? SOme dictionaries I save have significantly large data, so copy may not be very nice solution always.

[mauro3]

Note that this also happens to dicts nested within other data:

julia> using BSON

julia> d = [Dict(:a => [1+2im, 3+4im], :b => "Hello, World!")]
1-element Array{Dict{Symbol,Any},1}:
 Dict(:a=>Complex{Int64}[1+2im, 3+4im],:b=>"Hello, World!")

julia> bson("/tmp/test.bson", Dict(:d=>d))

julia> d[1]
Dict{Symbol,Any} with 2 entries:
  :a => Dict{Symbol,Any}(:tag=>"array",:type=>Dict{Symbol,Any}(:tag=>"datatype",:params=>Any[Dict{Symbol,Any}(:tag=>"datatype",:params=>Any[],:name=>Any["Main", "Core",…
  :b => "Hello, World!"

And also note that this is also present in v0.14, the last Julia 0.6 version.

[mauro3]

A workaround:

julia> d = Dict{Any,Any}(:a => [1+2im, 3+4im], :b => "Hello, World!")
Dict{Any,Any} with 2 entries:
  :a => Complex{Int64}[1+2im, 3+4im]
  :b => "Hello, World!"

julia> bson("/tmp/test.bson", d)

julia> d
Dict{Any,Any} with 2 entries:
  :a => Complex{Int64}[1+2im, 3+4im]
  :b => "Hello, World!"

[Datseris]

So the workaround is to define the dictionary as {Any, Any} ?

[mauro3]

Yes

[mauro3]

In #29 is a start to fix this. But I cannot spend more time on it. Maybe one of you can?

[racinmat]

The workaround does not work for me :(
I have some deep structure in sch, and all of these are mutating the sch

BSON.bson("sth.bson", Dict{Any, Any}(:a=>sch))
BSON.bson("sth.bson", Dict{Any, Any}("a"=>sch))
BSON.bson("sth.bson", Dict("a"=>sch))

Btw, I think tt should be somewhere more clearly stated that the serialization function modifies the argument, it caused me some nasty bugs, looking forward to the merge.