Make AWSConfig its own type

Rather than defining `AWSConfig` as a `SymbolDict` with no restrictions
on the contents, we can make it its own type, which gives more control
over how things are stored and accessed.

Fixes #53

Author: ararslan

src/AWSCore.jl

@@ -22,17 +22,69 @@ using DataStructures: OrderedDict
 using JSON
 using LazyJSON
 
+# NOTE: This needs to be defined before AWSConfig. Methods defined on AWSCredentials are
+# in src/AWSCredentials.jl.
+"""
+    AWSCredentials
+
+A type which holds AWS credentials.
+When you interact with AWS, you specify your
+[AWS Security Credentials](http://docs.aws.amazon.com/general/latest/gr/aws-security-credentials.html)
+to verify who you are and whether you have permission to access the resources that you are
+requesting. AWS uses the security credentials to authenticate and authorize your requests.
+
+The fields `access_key_id` and `secret_key` hold the access keys used to authenticate API
+requests (see [Creating, Modifying, and Viewing Access
+Keys](http://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html#Using_CreateAccessKey)).
+
+[Temporary Security Credentials](http://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp.html)
+require the extra session `token` field.
 
+The `user_arn` and `account_number` fields are used to cache the result of the
+[`aws_user_arn`](@ref) and [`aws_account_number`](@ref) functions.
+
+The `AWSCredentials()` constructor tries to load local Credentials from
+environment variables, `~/.aws/credentials`, `~/.aws/config`, or EC2 instance credentials.
+To specify the profile to use from `~/.aws/credentials`, do, for example,
+`AWSCredentials(profile="profile-name")`.
 """
-Most `AWSCore` functions take a `AWSConfig` dictionary as the first argument.
-This dictionary holds [`AWSCredentials`](@ref) and AWS region configuration.
+mutable struct AWSCredentials
+    access_key_id::String
+    secret_key::String
+    token::String
+    user_arn::String
+    account_number::String
+
+    function AWSCredentials(access_key_id, secret_key,
+                            token="", user_arn="", account_number="")
+        new(access_key_id, secret_key, token, user_arn, account_number)
+    end
+end
 
-```julia
-aws = AWSConfig(:creds => AWSCredentials(), :region => "us-east-1")`
+"""
+    AWSConfig
+
+Most `AWSCore` functions take an `AWSConfig` object as the first argument.
+This type holds [`AWSCredentials`](@ref), region, and output configuration.
+
+```julia-repl
+julia> AWSConfig(creds=AWSCredentials(), region="us-east-1")
+AWSConfig((AKIDEXAMPLE, wJa...)
+, "us-east-1", "json")
 ```
 """
-const AWSConfig = SymbolDict
+mutable struct AWSConfig
+    creds::AWSCredentials
+    region::String
+    output::String
+end
+AWSConfig(; creds, region, output="json") = AWSConfig(creds, region, output)
 
+# Relics of using SymbolDict
+import Base: getindex, setindex!
+Base.@deprecate AWSConfig(pairs::Pair...) AWSConfig(; pairs...)
+Base.@deprecate getindex(conf::AWSConfig, x::Symbol) getfield(conf, x)
+Base.@deprecate setindex!(conf::AWSConfig, val, var::Symbol) setfield!(conf, var, val)
 
 """
 The `AWSRequest` dictionary describes a single API request:
@@ -57,7 +109,6 @@ include("names.jl")
 include("mime.jl")
 
 
-
 #------------------------------------------------------------------------------#
 # Configuration.
 #------------------------------------------------------------------------------#

src/AWSCredentials.jl

@@ -17,32 +17,7 @@ export AWSCredentials,
        aws_account_number
 
 
-"""
-When you interact with AWS, you specify your [AWS Security Credentials](http://docs.aws.amazon.com/general/latest/gr/aws-security-credentials.html) to verify who you are and whether you have permission to access the resources that you are requesting. AWS uses the security credentials to authenticate and authorize your requests.
-
-The fields `access_key_id` and `secret_key` hold the access keys used to authenticate API requests (see [Creating, Modifying, and Viewing Access Keys](http://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html#Using_CreateAccessKey)).
-
-[Temporary Security Credentials](http://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp.html) require the extra session `token` field.
-
-
-The `user_arn` and `account_number` fields are used to cache the result of the [`aws_user_arn`](@ref) and [`aws_account_number`](@ref) functions.
-
-The `AWSCredentials()` constructor tries to load local Credentials from
-environment variables, `~/.aws/credentials`, `~/.aws/config` or EC2 instance credentials.
-To specify the profile to use from `~/.aws/credentials`, do, for example, `AWSCredentials(profile="profile-name")`.
-"""
-mutable struct AWSCredentials
-    access_key_id::String
-    secret_key::String
-    token::String
-    user_arn::String
-    account_number::String
-
-    function AWSCredentials(access_key_id, secret_key,
-                            token="", user_arn="", account_number="")
-        new(access_key_id, secret_key, token, user_arn, account_number)
-    end
-end
+# AWSCredentials type defined in src/AWSCore.jl
 
 function Base.show(io::IO,c::AWSCredentials)
     println(io, string(c.user_arn,
@@ -322,7 +297,7 @@ function aws_get_role(role::AbstractString, ini::Inifile)
     end
     credentials = dot_aws_credentials(source_profile)
 
-    config = AWSConfig(:creds=>credentials, :region=>aws_get_region(source_profile, ini))
+    config = AWSConfig(creds=credentials, region=aws_get_region(source_profile, ini))
 
     role = Services.sts(
         config,