From fc80acd41caa57897c6595b89c420418cbf78510 Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <cuvelier.thibaut@gmail.com>
Date: Tue, 29 Oct 2019 17:11:45 +0100
Subject: [PATCH 1/8] Implementations of writeLP and writeMPS that use
 MathOptFormat.

---
 Project.toml | 1 +
 src/JuMP.jl  | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Project.toml b/Project.toml
index bf486700f75..08900786e44 100644
--- a/Project.toml
+++ b/Project.toml
@@ -8,6 +8,7 @@ Calculus = "49dc2e85-a5d0-5ad3-a950-438e2897f1b9"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+MathOptFormat = "f3a3d49f-3211-5bb3-8051-36b1456cf382"
 MathOptInterface = "b8f27783-ece8-5eb3-8dc8-9495eed66fee"
 NaNMath = "77ba4419-2d1f-58cd-9bb1-8ffee604a2e3"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
diff --git a/src/JuMP.jl b/src/JuMP.jl
index 010d911975f..6239f8e1e27 100644
--- a/src/JuMP.jl
+++ b/src/JuMP.jl
@@ -16,6 +16,7 @@ using SparseArrays
 import MathOptInterface
 const MOI = MathOptInterface
 const MOIU = MOI.Utilities
+using MathOptFormat
 
 import Calculus
 import DataStructures.OrderedDict
@@ -38,8 +39,8 @@ Base.@deprecate(setlowerbound,     JuMP.set_lower_bound)
 Base.@deprecate(setupperbound,     JuMP.set_upper_bound)
 Base.@deprecate(linearterms,       JuMP.linear_terms)
 
-writeLP(args...; kargs...) = error("writeLP has been removed from JuMP. Use `MathOptFormat.jl` instead.")
-writeMPS(args...; kargs...) = error("writeMPS has been removed from JuMP. Use `MathOptFormat.jl` instead.")
+writeLP(args...; kargs...) = error("writeLP has been renamed to write_LP and its arguments have changed.")
+writeMPS(args...; kargs...) = error("writeMPS has been renamed to write_MPS and its arguments have changed.")
 
 include("utils.jl")
 

From 323d1f0cb0e0d476a7c6eb06a76f9086f360d97d Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <cuvelier.thibaut@gmail.com>
Date: Tue, 29 Oct 2019 17:12:20 +0100
Subject: [PATCH 2/8] Propose a unified API.

---
 src/JuMP.jl   |  5 ++--
 src/export.jl | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+), 2 deletions(-)
 create mode 100644 src/export.jl

diff --git a/src/JuMP.jl b/src/JuMP.jl
index 6239f8e1e27..cd375339cf5 100644
--- a/src/JuMP.jl
+++ b/src/JuMP.jl
@@ -39,8 +39,8 @@ Base.@deprecate(setlowerbound,     JuMP.set_lower_bound)
 Base.@deprecate(setupperbound,     JuMP.set_upper_bound)
 Base.@deprecate(linearterms,       JuMP.linear_terms)
 
-writeLP(args...; kargs...) = error("writeLP has been renamed to write_LP and its arguments have changed.")
-writeMPS(args...; kargs...) = error("writeMPS has been renamed to write_MPS and its arguments have changed.")
+writeLP(args...; kargs...) = error("writeLP has been merged into write_to_file and its arguments have changed.")
+writeMPS(args...; kargs...) = error("writeMPS has been merged into write_to_file and its arguments have changed.")
 
 include("utils.jl")
 
@@ -788,6 +788,7 @@ include("nlp.jl")
 include("print.jl")
 include("lp_sensitivity.jl")
 include("callbacks.jl")
+include("export.jl")
 
 # JuMP exports everything except internal symbols, which are defined as those
 # whose name starts with an underscore. If you don't want all of these symbols
diff --git a/src/export.jl b/src/export.jl
new file mode 100644
index 00000000000..1fa8b623f8f
--- /dev/null
+++ b/src/export.jl
@@ -0,0 +1,78 @@
+"List of accepted export formats. `Automatic` corresponds to a detection from the file name."
+@enum(FileFormat, CBF, LP, MOF, MPS, Automatic)
+
+function _filename_to_format(filename::String)
+    return if endswith(filename, ".mof.json.gz") || endswith(filename, ".mof.json")
+        MOF
+    elseif endswith(filename, ".cbf.gz") || endswith(filename, ".cbf")
+        CBF
+    elseif endswith(filename, ".mps.gz") || endswith(filename, ".mps")
+        MPS
+    elseif endswith(filename, ".lp.gz") || endswith(filename, ".lp")
+        LP
+    else
+        error("File type of $(filename) not recognized by JuMP.")
+    end
+end
+
+"List of accepted export compression formats. `Automatic` corresponds to a detection from the file name."
+@enum(FileCompression, None, GZip, Automatic)
+
+function _filename_to_compression(filename::String)
+    return if endswith(filename, ".gz")
+        GZip
+    else
+        None
+    end
+end
+
+function _open(f::Function, filename::String, mode::String; compression::FileCompression=Automatic)
+    if compression == Automatic
+        compression = _filename_to_compression(filename)
+    end
+
+    open_f = if compression == GZip
+        GZip.open
+    else
+        open
+    end
+    return open_f(f, filename, mode)
+end
+
+function write_to_file(model::Model, io::IO, format::FileFormat=MPS; kwargs...)
+    dest = if format == CBF
+        MathOptFormat.CBF.Model(; kwargs...)
+    elseif format == LP
+        MathOptFormat.LP.Model(; kwargs...)
+    elseif format == MOF
+        MathOptFormat.MOF.Model(; kwargs...)
+    elseif format == MPS
+        MathOptFormat.MPS.Model(; kwargs...)
+    else
+        error("When passing an IO object to write_to_file, the file format cannot be guessed from the file name.")
+    end
+    MOI.copy_to(dest, backend(model))
+    MOI.write_to_file(dest, io)
+    return
+end
+
+"""
+    write_to_file(model::Model, filename::String; format::FileFormat=Automatic, compression::FileCompression=Automatic, kwargs...)
+
+Write `model` to the file called `filename` using the format `format`.
+
+Valid formats are given by the enum [`FileFormat`](@ref). Valid compression algorithms
+are given by the enum [`FileCompression`](@ref).
+
+For keyword options, see [MathOptFormat.jl](https://github.com/odow/MathOptFormat.jl).
+"""
+function write_to_file(model::Model, filename::String; format::FileFormat=Automatic, compression::FileCompression=Automatic, kwargs...)
+    if format == Automatic
+        format = _filename_to_format(filename)
+    end
+
+    _open(filename, "w", compression) do io
+        write_to_file(model, io, format; kwargs...)
+    end
+    return
+end

From 6068992c823f6c0f14b5cf7ece9a7d34998a842a Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <cuvelier.thibaut@gmail.com>
Date: Tue, 29 Oct 2019 22:34:21 +0100
Subject: [PATCH 3/8] Respond to @odow's comments.

---
 Project.toml                       |  1 +
 src/JuMP.jl                        |  2 ++
 src/{export.jl => file_formats.jl} | 42 ++++++++++++++++++------------
 3 files changed, 28 insertions(+), 17 deletions(-)
 rename src/{export.jl => file_formats.jl} (61%)

diff --git a/Project.toml b/Project.toml
index 08900786e44..8e08b7953b9 100644
--- a/Project.toml
+++ b/Project.toml
@@ -5,6 +5,7 @@ version = "0.20.0"
 
 [deps]
 Calculus = "49dc2e85-a5d0-5ad3-a950-438e2897f1b9"
+CodecZlib = "944b1d66-785c-5afd-91f1-9de20f533193"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
diff --git a/src/JuMP.jl b/src/JuMP.jl
index cd375339cf5..3bc3684e698 100644
--- a/src/JuMP.jl
+++ b/src/JuMP.jl
@@ -17,6 +17,7 @@ import MathOptInterface
 const MOI = MathOptInterface
 const MOIU = MOI.Utilities
 using MathOptFormat
+import CodecZlib
 
 import Calculus
 import DataStructures.OrderedDict
@@ -789,6 +790,7 @@ include("print.jl")
 include("lp_sensitivity.jl")
 include("callbacks.jl")
 include("export.jl")
+include("file_formats.jl")
 
 # JuMP exports everything except internal symbols, which are defined as those
 # whose name starts with an underscore. If you don't want all of these symbols
diff --git a/src/export.jl b/src/file_formats.jl
similarity index 61%
rename from src/export.jl
rename to src/file_formats.jl
index 1fa8b623f8f..f269992a91b 100644
--- a/src/export.jl
+++ b/src/file_formats.jl
@@ -1,5 +1,8 @@
-"List of accepted export formats. `Automatic` corresponds to a detection from the file name."
-@enum(FileFormat, CBF, LP, MOF, MPS, Automatic)
+"""
+List of accepted export formats. `AUTOMATIC_FILE_FORMAT` corresponds to
+a detection from the file name.
+"""
+@enum(FileFormat, CBF, LP, MOF, MPS, AUTOMATIC_FILE_FORMAT)
 
 function _filename_to_format(filename::String)
     return if endswith(filename, ".mof.json.gz") || endswith(filename, ".mof.json")
@@ -15,31 +18,34 @@ function _filename_to_format(filename::String)
     end
 end
 
-"List of accepted export compression formats. `Automatic` corresponds to a detection from the file name."
-@enum(FileCompression, None, GZip, Automatic)
+"""
+List of accepted export compression formats. `AUTOMATIC_FILE_COMPRESSION`
+corresponds to a detection from the file name.
+"""
+@enum(FileCompression, NO_FILE_COMPRESSION, GZIP, AUTOMATIC_FILE_COMPRESSION)
 
 function _filename_to_compression(filename::String)
     return if endswith(filename, ".gz")
-        GZip
+        GZIP
     else
-        None
+        NO_FILE_COMPRESSION
     end
 end
 
-function _open(f::Function, filename::String, mode::String; compression::FileCompression=Automatic)
-    if compression == Automatic
+function _open(f::Function, filename::String, mode::String; compression::FileCompression=AUTOMATIC_FILE_COMPRESSION)
+    if compression == AUTOMATIC_FILE_COMPRESSION
         compression = _filename_to_compression(filename)
     end
 
-    open_f = if compression == GZip
-        GZip.open
+    if compression == GZIP
+        stream = (mode == "r") ? CodecZlib.GzipDecompressorStream : CodecZlib.GzipCompressorStream
+        return open(f, stream, filename, mode)
     else
-        open
+        return open(f, filename, mode)
     end
-    return open_f(f, filename, mode)
 end
 
-function write_to_file(model::Model, io::IO, format::FileFormat=MPS; kwargs...)
+function write_to_file(model::Model, io::IO, format::FileFormat; kwargs...)
     dest = if format == CBF
         MathOptFormat.CBF.Model(; kwargs...)
     elseif format == LP
@@ -57,7 +63,7 @@ function write_to_file(model::Model, io::IO, format::FileFormat=MPS; kwargs...)
 end
 
 """
-    write_to_file(model::Model, filename::String; format::FileFormat=Automatic, compression::FileCompression=Automatic, kwargs...)
+    write_to_file(model::Model, filename::String; format::FileFormat=AUTOMATIC_FILE_FORMAT, compression::FileCompression=AUTOMATIC_FILE_COMPRESSION, kwargs...)
 
 Write `model` to the file called `filename` using the format `format`.
 
@@ -66,12 +72,14 @@ are given by the enum [`FileCompression`](@ref).
 
 For keyword options, see [MathOptFormat.jl](https://github.com/odow/MathOptFormat.jl).
 """
-function write_to_file(model::Model, filename::String; format::FileFormat=Automatic, compression::FileCompression=Automatic, kwargs...)
-    if format == Automatic
+function write_to_file(model::Model, filename::String; format::FileFormat=AUTOMATIC_FILE_FORMAT, compression::FileCompression=AUTOMATIC_FILE_COMPRESSION, kwargs...)
+    if format == AUTOMATIC_FILE_FORMAT
         format = _filename_to_format(filename)
     end
 
-    _open(filename, "w", compression) do io
+    # println((filename, "w", compression))
+
+    _open(filename, "w", compression=compression) do io
         write_to_file(model, io, format; kwargs...)
     end
     return

From 0c53815c026ee3aadca0d0ce497de30fca87bd5b Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <cuvelier.thibaut@gmail.com>
Date: Tue, 29 Oct 2019 22:56:49 +0100
Subject: [PATCH 4/8] Correct Project.toml.

---
 Project.toml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 8e08b7953b9..7c5967d887b 100644
--- a/Project.toml
+++ b/Project.toml
@@ -9,10 +9,11 @@ CodecZlib = "944b1d66-785c-5afd-91f1-9de20f533193"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
-MathOptFormat = "f3a3d49f-3211-5bb3-8051-36b1456cf382"
+MathOptFormat = "f4570300-c277-12e8-125c-4912f86ce65d"
 MathOptInterface = "b8f27783-ece8-5eb3-8dc8-9495eed66fee"
 NaNMath = "77ba4419-2d1f-58cd-9bb1-8ffee604a2e3"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
+Revise = "295af30f-e4ad-537b-8983-00126c2a3abe"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
@@ -20,6 +21,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 Calculus = "0.5"
 DataStructures = "0.17"
 ForwardDiff = "~0.5.0, ~0.6, ~0.7, ~0.8, ~0.9, ~0.10"
+MathOptFormat = "≥ 0.2"
 MathOptInterface = "~0.9.1"
 NaNMath = "0.3"
 OffsetArrays = "≥ 0.2.13"

From b82f70cfeba2171f53746f198e581a7bb798b9bf Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <cuvelier.thibaut@gmail.com>
Date: Wed, 30 Oct 2019 01:24:11 +0100
Subject: [PATCH 5/8] Implement more compression formats.

---
 Project.toml        |  3 ++-
 src/JuMP.jl         |  2 ++
 src/file_formats.jl | 20 ++++++++++++++------
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/Project.toml b/Project.toml
index 7c5967d887b..5b7a6c3dfb5 100644
--- a/Project.toml
+++ b/Project.toml
@@ -5,6 +5,8 @@ version = "0.20.0"
 
 [deps]
 Calculus = "49dc2e85-a5d0-5ad3-a950-438e2897f1b9"
+CodecBzip2 = "523fee87-0ab8-5b00-afb7-3ecf72e48cfd"
+CodecXz = "ba30903b-d9e8-5048-a5ec-d1f5b0d4b47b"
 CodecZlib = "944b1d66-785c-5afd-91f1-9de20f533193"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
@@ -13,7 +15,6 @@ MathOptFormat = "f4570300-c277-12e8-125c-4912f86ce65d"
 MathOptInterface = "b8f27783-ece8-5eb3-8dc8-9495eed66fee"
 NaNMath = "77ba4419-2d1f-58cd-9bb1-8ffee604a2e3"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
-Revise = "295af30f-e4ad-537b-8983-00126c2a3abe"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
diff --git a/src/JuMP.jl b/src/JuMP.jl
index 3bc3684e698..37791357741 100644
--- a/src/JuMP.jl
+++ b/src/JuMP.jl
@@ -17,6 +17,8 @@ import MathOptInterface
 const MOI = MathOptInterface
 const MOIU = MOI.Utilities
 using MathOptFormat
+import CodecBzip2
+import CodecXz
 import CodecZlib
 
 import Calculus
diff --git a/src/file_formats.jl b/src/file_formats.jl
index f269992a91b..afe54e09804 100644
--- a/src/file_formats.jl
+++ b/src/file_formats.jl
@@ -22,11 +22,15 @@ end
 List of accepted export compression formats. `AUTOMATIC_FILE_COMPRESSION`
 corresponds to a detection from the file name.
 """
-@enum(FileCompression, NO_FILE_COMPRESSION, GZIP, AUTOMATIC_FILE_COMPRESSION)
+@enum(FileCompression, NO_FILE_COMPRESSION, BZIP2, GZIP, XZ, AUTOMATIC_FILE_COMPRESSION)
 
 function _filename_to_compression(filename::String)
-    return if endswith(filename, ".gz")
+    return if endswith(filename, ".bz2")
+        BZIP2
+    elseif endswith(filename, ".gz")
         GZIP
+    elseif endswith(filename, ".xz")
+        XZ
     else
         NO_FILE_COMPRESSION
     end
@@ -37,8 +41,14 @@ function _open(f::Function, filename::String, mode::String; compression::FileCom
         compression = _filename_to_compression(filename)
     end
 
-    if compression == GZIP
-        stream = (mode == "r") ? CodecZlib.GzipDecompressorStream : CodecZlib.GzipCompressorStream
+    if compression == BZIP2 || compression == GZIP || compression == XZ
+        stream = if compression == BZIP2
+            (mode == "r") ? CodecBzip2.Bzip2DecompressorStream : CodecBzip2.Bzip2CompressorStream
+        elseif compression == GZIP
+            (mode == "r") ? CodecZlib.GzipDecompressorStream : CodecZlib.GzipCompressorStream
+        else # compression == XZ
+            (mode == "r") ? CodecXz.XzDecompressorStream : CodecXz.XzCompressorStream
+        end
         return open(f, stream, filename, mode)
     else
         return open(f, filename, mode)
@@ -77,8 +87,6 @@ function write_to_file(model::Model, filename::String; format::FileFormat=AUTOMA
         format = _filename_to_format(filename)
     end
 
-    # println((filename, "w", compression))
-
     _open(filename, "w", compression=compression) do io
         write_to_file(model, io, format; kwargs...)
     end

From 6991b86ee83b41e7703e7eb04c7ebffdf89c8f76 Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <cuvelier.thibaut@gmail.com>
Date: Wed, 30 Oct 2019 02:31:02 +0100
Subject: [PATCH 6/8] Move most of the code to MathOptFormat.

---
 Project.toml        |  3 --
 src/JuMP.jl         |  3 --
 src/file_formats.jl | 79 +++++----------------------------------------
 3 files changed, 8 insertions(+), 77 deletions(-)

diff --git a/Project.toml b/Project.toml
index 5b7a6c3dfb5..8fed4af432e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -5,9 +5,6 @@ version = "0.20.0"
 
 [deps]
 Calculus = "49dc2e85-a5d0-5ad3-a950-438e2897f1b9"
-CodecBzip2 = "523fee87-0ab8-5b00-afb7-3ecf72e48cfd"
-CodecXz = "ba30903b-d9e8-5048-a5ec-d1f5b0d4b47b"
-CodecZlib = "944b1d66-785c-5afd-91f1-9de20f533193"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
diff --git a/src/JuMP.jl b/src/JuMP.jl
index 37791357741..52852a9501c 100644
--- a/src/JuMP.jl
+++ b/src/JuMP.jl
@@ -17,9 +17,6 @@ import MathOptInterface
 const MOI = MathOptInterface
 const MOIU = MOI.Utilities
 using MathOptFormat
-import CodecBzip2
-import CodecXz
-import CodecZlib
 
 import Calculus
 import DataStructures.OrderedDict
diff --git a/src/file_formats.jl b/src/file_formats.jl
index afe54e09804..90197fbeb99 100644
--- a/src/file_formats.jl
+++ b/src/file_formats.jl
@@ -1,72 +1,6 @@
-"""
-List of accepted export formats. `AUTOMATIC_FILE_FORMAT` corresponds to
-a detection from the file name.
-"""
-@enum(FileFormat, CBF, LP, MOF, MPS, AUTOMATIC_FILE_FORMAT)
-
-function _filename_to_format(filename::String)
-    return if endswith(filename, ".mof.json.gz") || endswith(filename, ".mof.json")
-        MOF
-    elseif endswith(filename, ".cbf.gz") || endswith(filename, ".cbf")
-        CBF
-    elseif endswith(filename, ".mps.gz") || endswith(filename, ".mps")
-        MPS
-    elseif endswith(filename, ".lp.gz") || endswith(filename, ".lp")
-        LP
-    else
-        error("File type of $(filename) not recognized by JuMP.")
-    end
-end
-
-"""
-List of accepted export compression formats. `AUTOMATIC_FILE_COMPRESSION`
-corresponds to a detection from the file name.
-"""
-@enum(FileCompression, NO_FILE_COMPRESSION, BZIP2, GZIP, XZ, AUTOMATIC_FILE_COMPRESSION)
-
-function _filename_to_compression(filename::String)
-    return if endswith(filename, ".bz2")
-        BZIP2
-    elseif endswith(filename, ".gz")
-        GZIP
-    elseif endswith(filename, ".xz")
-        XZ
-    else
-        NO_FILE_COMPRESSION
-    end
-end
-
-function _open(f::Function, filename::String, mode::String; compression::FileCompression=AUTOMATIC_FILE_COMPRESSION)
-    if compression == AUTOMATIC_FILE_COMPRESSION
-        compression = _filename_to_compression(filename)
-    end
-
-    if compression == BZIP2 || compression == GZIP || compression == XZ
-        stream = if compression == BZIP2
-            (mode == "r") ? CodecBzip2.Bzip2DecompressorStream : CodecBzip2.Bzip2CompressorStream
-        elseif compression == GZIP
-            (mode == "r") ? CodecZlib.GzipDecompressorStream : CodecZlib.GzipCompressorStream
-        else # compression == XZ
-            (mode == "r") ? CodecXz.XzDecompressorStream : CodecXz.XzCompressorStream
-        end
-        return open(f, stream, filename, mode)
-    else
-        return open(f, filename, mode)
-    end
-end
-
-function write_to_file(model::Model, io::IO, format::FileFormat; kwargs...)
-    dest = if format == CBF
-        MathOptFormat.CBF.Model(; kwargs...)
-    elseif format == LP
-        MathOptFormat.LP.Model(; kwargs...)
-    elseif format == MOF
-        MathOptFormat.MOF.Model(; kwargs...)
-    elseif format == MPS
-        MathOptFormat.MPS.Model(; kwargs...)
-    else
-        error("When passing an IO object to write_to_file, the file format cannot be guessed from the file name.")
-    end
+function write_to_file(model::Model, io::IO, format::MathOptFormat.FileFormat; kwargs...)
+    @assert format != AUTOMATIC_FILE_FORMAT
+    dest = MathOptFormat._file_formats[format]()
     MOI.copy_to(dest, backend(model))
     MOI.write_to_file(dest, io)
     return
@@ -82,12 +16,15 @@ are given by the enum [`FileCompression`](@ref).
 
 For keyword options, see [MathOptFormat.jl](https://github.com/odow/MathOptFormat.jl).
 """
-function write_to_file(model::Model, filename::String; format::FileFormat=AUTOMATIC_FILE_FORMAT, compression::FileCompression=AUTOMATIC_FILE_COMPRESSION, kwargs...)
+function write_to_file(model::Model, filename::String;
+                       format::MathOptFormat.FileFormat=MathOptFormat.AUTOMATIC_FILE_FORMAT,
+                       compression::MathOptFormat.FileCompression=AUTOMATIC_FILE_COMPRESSION,
+                       kwargs...)
     if format == AUTOMATIC_FILE_FORMAT
         format = _filename_to_format(filename)
     end
 
-    _open(filename, "w", compression=compression) do io
+    MathOptFormat.gzip_open(filename, "w", compression=compression) do io
         write_to_file(model, io, format; kwargs...)
     end
     return

From 3e27c6ea9ecd09d928afd40ae1640d773767f134 Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <cuvelier.thibaut@gmail.com>
Date: Tue, 26 Nov 2019 18:38:43 +0100
Subject: [PATCH 7/8] Update to MOF#master.

---
 src/file_formats.jl | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/src/file_formats.jl b/src/file_formats.jl
index 90197fbeb99..6d070920b9e 100644
--- a/src/file_formats.jl
+++ b/src/file_formats.jl
@@ -1,31 +1,28 @@
 function write_to_file(model::Model, io::IO, format::MathOptFormat.FileFormat; kwargs...)
     @assert format != AUTOMATIC_FILE_FORMAT
-    dest = MathOptFormat._file_formats[format]()
+    dest = MathOptFormat._file_formats[format][2]()
     MOI.copy_to(dest, backend(model))
     MOI.write_to_file(dest, io)
     return
 end
 
 """
-    write_to_file(model::Model, filename::String; format::FileFormat=AUTOMATIC_FILE_FORMAT, compression::FileCompression=AUTOMATIC_FILE_COMPRESSION, kwargs...)
+    write_to_file(model::Model, filename::String; format::FileFormat=AUTOMATIC_FILE_FORMAT, compression::MathOptFormat.AbstractCompressionScheme=MathOptFormat.AutomaticCompression(), kwargs...)
 
 Write `model` to the file called `filename` using the format `format`.
 
 Valid formats are given by the enum [`FileFormat`](@ref). Valid compression algorithms
-are given by the enum [`FileCompression`](@ref).
+are given by a concrete subtype of [`AbstractCompressionScheme`](@ref).
 
 For keyword options, see [MathOptFormat.jl](https://github.com/odow/MathOptFormat.jl).
 """
 function write_to_file(model::Model, filename::String;
                        format::MathOptFormat.FileFormat=MathOptFormat.AUTOMATIC_FILE_FORMAT,
-                       compression::MathOptFormat.FileCompression=AUTOMATIC_FILE_COMPRESSION,
+                       compression::MathOptFormat.AbstractCompressionScheme=MathOptFormat.AutomaticCompression(),
                        kwargs...)
     if format == AUTOMATIC_FILE_FORMAT
-        format = _filename_to_format(filename)
-    end
-
-    MathOptFormat.gzip_open(filename, "w", compression=compression) do io
-        write_to_file(model, io, format; kwargs...)
+        format = MathOptFormat._filename_to_format(filename)
     end
+    MOI.write_to_file(model, filename, compression=compression)
     return
 end

From e1679eb173702cb869afc9fae18e55c2736ccd4c Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <cuvelier.thibaut@gmail.com>
Date: Tue, 26 Nov 2019 23:27:54 +0100
Subject: [PATCH 8/8] Rebasing mistake.

---
 src/JuMP.jl | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/JuMP.jl b/src/JuMP.jl
index 52852a9501c..f688a37e7d4 100644
--- a/src/JuMP.jl
+++ b/src/JuMP.jl
@@ -788,7 +788,6 @@ include("nlp.jl")
 include("print.jl")
 include("lp_sensitivity.jl")
 include("callbacks.jl")
-include("export.jl")
 include("file_formats.jl")
 
 # JuMP exports everything except internal symbols, which are defined as those