From abe03ab04d1a3920f75ac68878951a5943379840 Mon Sep 17 00:00:00 2001
From: Nathan Daly <nhdaly@gmail.com>
Date: Sat, 26 Jan 2019 19:01:39 -0500
Subject: [PATCH 1/6] Add Channel{T}(f::Function) constructors.

The Channel constructors that do and don't create a Task are currently
written in different styles:

 - The non-Task constructor takes a Type {T} as a type parameter, and
 the size as a positional argument.
    - `Channel{Int}(Inf)`
    - `Channel(0)`

 - The Task constructor takes a Function, but the size and type are
keyword arguments:
    - `Channel(c->put!(c,0), ctype=Int, csize=0)`
    - `Channel(ctype=Int, csize=0, taskref=t) do c; put!(c,0); end`

This commit adds convenience methods to the Task-creating constructor,
allowing you to specify the Type and/or size as in the non-Task
constructor:
    - `Channel{Char}(1) do c; put!(c, 'a'); end`
    - `Channel{Char}(csize=2, taskref=t) do c; put!(c, 'a'); end`

---

Also adds tests for the existing Task-creating constructors, which
weren't explicitly tested before.
---
 base/channels.jl | 22 ++++++++++++++++++++++
 test/channels.jl | 26 ++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/base/channels.jl b/base/channels.jl
index 1cb6b5386f960..c29c2e29e017d 100644
--- a/base/channels.jl
+++ b/base/channels.jl
@@ -95,6 +95,22 @@ Hello
 julia> istaskdone(taskref[])
 true
 ```
+
+Other constructors:
+* `Channel{T}(func::Function, sz=0)`
+* `Channel{T}(func::Function; csize=0, taskref=nothing)`
+
+```jldoctest
+julia> chnl = Channel{Char}(1) do ch
+           for c in "hello world"
+               put!(ch, c)
+           end
+       end
+>> Channel{Char}(sz_max:1,sz_curr:1)
+
+julia> String(collect(chnl))
+>> "hello world"
+```
 """
 function Channel(func::Function; ctype=Any, csize=0, taskref=nothing)
     chnl = Channel{ctype}(csize)
@@ -105,6 +121,12 @@ function Channel(func::Function; ctype=Any, csize=0, taskref=nothing)
     isa(taskref, Ref{Task}) && (taskref[] = task)
     return chnl
 end
+function Channel{T}(f::Function, sz=0) where T
+    return Channel(f, csize=sz, ctype=T)
+end
+function Channel{T}(f::Function; csize=0, taskref=nothing) where T
+    return Channel(f, csize=csize, ctype=T, taskref=taskref)
+end
 
 
 closed_exception() = InvalidStateException("Channel is closed.", :closed)
diff --git a/test/channels.jl b/test/channels.jl
index 2583e2f8e4e39..cdbc341d26663 100644
--- a/test/channels.jl
+++ b/test/channels.jl
@@ -36,6 +36,32 @@ end
     @test_throws InexactError Channel(1.5)
 end
 
+@testset "Task constructors" begin
+    c = Channel(ctype=Float32, csize=2) do c; map(i->put!(c,i), 1:100); end
+    @test eltype(c) == Float32
+    @test c.sz_max == 2
+    @test isopen(c)
+    @test collect(c) == 1:100
+
+    c = Channel{Int}() do c; map(i->put!(c,i), 1:100); end
+    @test eltype(c) == Int
+    @test c.sz_max == 0
+    @test collect(c) == 1:100
+
+    c = Channel{Int}(Inf) do c; put!(c,1); end
+    @test eltype(c) == Int
+    @test c.sz_max == typemax(Int)
+
+    taskref = Ref{Task}()
+    c = Channel{Int}(csize=0, taskref=taskref) do c; put!(c, 0); end
+    @test eltype(c) == Int
+    @test c.sz_max == 0
+    @test istaskstarted(taskref[])
+    @test !istaskdone(taskref[])
+    take!(c); yield()
+    @test istaskdone(taskref[])
+end
+
 @testset "multiple concurrent put!/take! on a channel for different sizes" begin
     function testcpt(sz)
         c = Channel{Int}(sz)

From eb37c0e7876aca134d19940a183d14bb54820690 Mon Sep 17 00:00:00 2001
From: Nathan Daly <nhdaly@gmail.com>
Date: Sat, 26 Jan 2019 19:39:12 -0500
Subject: [PATCH 2/6] Fix test: switch `yield()` to `wait(taskref[])`

---
 test/channels.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/channels.jl b/test/channels.jl
index cdbc341d26663..52ea021393747 100644
--- a/test/channels.jl
+++ b/test/channels.jl
@@ -58,7 +58,7 @@ end
     @test c.sz_max == 0
     @test istaskstarted(taskref[])
     @test !istaskdone(taskref[])
-    take!(c); yield()
+    take!(c); wait(taskref[])
     @test istaskdone(taskref[])
 end
 

From e0481cb9448db2bec29c1de2157f0ace48a094df Mon Sep 17 00:00:00 2001
From: Nathan Daly <nhdaly@gmail.com>
Date: Mon, 1 Jul 2019 16:42:23 -0400
Subject: [PATCH 3/6] Add !!! compat "Julia 1.3" message

---
 base/channels.jl | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/base/channels.jl b/base/channels.jl
index c29c2e29e017d..4aac83b3893df 100644
--- a/base/channels.jl
+++ b/base/channels.jl
@@ -96,6 +96,9 @@ julia> istaskdone(taskref[])
 true
 ```
 
+!!! compat "Julia 1.3"
+  The following constructors were added in Julia 1.3.
+
 Other constructors:
 * `Channel{T}(func::Function, sz=0)`
 * `Channel{T}(func::Function; csize=0, taskref=nothing)`

From d5cad7464b19636f856a6e386acd356bdd7cb8ec Mon Sep 17 00:00:00 2001
From: Nathan Daly <nhdaly@gmail.com>
Date: Mon, 1 Jul 2019 16:44:46 -0400
Subject: [PATCH 4/6] Add `Channel()` constr, defaults to unbufferred channel

Add unit tests for default constructor
---
 base/channels.jl | 7 ++++++-
 test/channels.jl | 8 +++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/base/channels.jl b/base/channels.jl
index 4aac83b3893df..0c6ce4bfd8e43 100644
--- a/base/channels.jl
+++ b/base/channels.jl
@@ -8,7 +8,7 @@ Representation of a channel passing objects of type `T`.
 abstract type AbstractChannel{T} end
 
 """
-    Channel{T}(sz::Int)
+    Channel{T}(sz::Int=0)
 
 Constructs a `Channel` with an internal buffer that can hold a maximum of `sz` objects
 of type `T`.
@@ -19,8 +19,12 @@ And vice-versa.
 
 Other constructors:
 
+* `Channel()`: default constructor, equivalent to `Channel{Any}(0)`
 * `Channel(Inf)`: equivalent to `Channel{Any}(typemax(Int))`
 * `Channel(sz)`: equivalent to `Channel{Any}(sz)`
+
+!!! compat "Julia 1.3"
+  The default constructor `Channel()` was added in Julia 1.3.
 """
 mutable struct Channel{T} <: AbstractChannel{T}
     cond_take::Threads.Condition                 # waiting for data to become available
@@ -48,6 +52,7 @@ function Channel{T}(sz::Float64) where T
     return Channel{T}(sz)
 end
 Channel(sz) = Channel{Any}(sz)
+Channel() = Channel{Any}(0)
 
 # special constructors
 """
diff --git a/test/channels.jl b/test/channels.jl
index 52ea021393747..5aa6fc83a6134 100644
--- a/test/channels.jl
+++ b/test/channels.jl
@@ -13,6 +13,9 @@ using Random
 end
 
 @testset "various constructors" begin
+    c = Channel()
+    @test eltype(c) == Any
+
     c = Channel(1)
     @test eltype(c) == Any
     @test put!(c, 1) == 1
@@ -31,7 +34,6 @@ end
     tvals = Int[take!(c) for i in 1:10^6]
     @test pvals == tvals
 
-    @test_throws MethodError Channel()
     @test_throws ArgumentError Channel(-1)
     @test_throws InexactError Channel(1.5)
 end
@@ -48,6 +50,10 @@ end
     @test c.sz_max == 0
     @test collect(c) == 1:100
 
+    c = Channel() do c; put!(c, 1); put!(c, "hi") end
+    @test c.sz_max == 0
+    @test collect(c) == [1, "hi"]
+
     c = Channel{Int}(Inf) do c; put!(c,1); end
     @test eltype(c) == Int
     @test c.sz_max == typemax(Int)

From 18a80ae7060138c0f30d795f2a8ba1376feda2e9 Mon Sep 17 00:00:00 2001
From: Nathan Daly <nhdaly@gmail.com>
Date: Mon, 1 Jul 2019 17:33:24 -0400
Subject: [PATCH 5/6] Add `Channel{Int}()` constructor, default to sz=0

---
 base/channels.jl | 4 ++--
 test/channels.jl | 5 +++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/base/channels.jl b/base/channels.jl
index 0c6ce4bfd8e43..2f4ebe9a9c7d7 100644
--- a/base/channels.jl
+++ b/base/channels.jl
@@ -24,7 +24,7 @@ Other constructors:
 * `Channel(sz)`: equivalent to `Channel{Any}(sz)`
 
 !!! compat "Julia 1.3"
-  The default constructor `Channel()` was added in Julia 1.3.
+  The default constructor `Channel()` and default `sz=0` were added in Julia 1.3.
 """
 mutable struct Channel{T} <: AbstractChannel{T}
     cond_take::Threads.Condition                 # waiting for data to become available
@@ -36,7 +36,7 @@ mutable struct Channel{T} <: AbstractChannel{T}
     data::Vector{T}
     sz_max::Int                          # maximum size of channel
 
-    function Channel{T}(sz::Integer) where T
+    function Channel{T}(sz::Integer = 0) where T
         if sz < 0
             throw(ArgumentError("Channel size must be either 0, a positive integer or Inf"))
         end
diff --git a/test/channels.jl b/test/channels.jl
index 5aa6fc83a6134..29a0ab52631da 100644
--- a/test/channels.jl
+++ b/test/channels.jl
@@ -15,6 +15,7 @@ end
 @testset "various constructors" begin
     c = Channel()
     @test eltype(c) == Any
+    @test c.sz_max == 0
 
     c = Channel(1)
     @test eltype(c) == Any
@@ -28,6 +29,10 @@ end
     @test eltype(c) == Int
     @test_throws MethodError put!(c, "Hello")
 
+    c = Channel{Int}()
+    @test eltype(c) == Int
+    @test c.sz_max == 0
+
     c = Channel{Int}(Inf)
     @test eltype(c) == Int
     pvals = map(i->put!(c,i), 1:10^6)

From 64109f4c371d830af6b0d590572d1e4a9a664a50 Mon Sep 17 00:00:00 2001
From: Nathan Daly <nhdaly@gmail.com>
Date: Tue, 2 Jul 2019 00:29:37 -0400
Subject: [PATCH 6/6] Oops: removed custom output prompt from jldoctest

I copy/pasted from my terminal, and I had a custom output prompt set via
OhMyREPL that I didn't notice.
---
 base/channels.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/base/channels.jl b/base/channels.jl
index 2f4ebe9a9c7d7..67899f97237db 100644
--- a/base/channels.jl
+++ b/base/channels.jl
@@ -114,10 +114,10 @@ julia> chnl = Channel{Char}(1) do ch
                put!(ch, c)
            end
        end
->> Channel{Char}(sz_max:1,sz_curr:1)
+Channel{Char}(sz_max:1,sz_curr:1)
 
 julia> String(collect(chnl))
->> "hello world"
+"hello world"
 ```
 """
 function Channel(func::Function; ctype=Any, csize=0, taskref=nothing)