move file validation to the constructor

some other small changes:

- validate_order: make sure `order` field is unique
- show: remove extra new line for AbstractDemoCard

Author: johnnychen94

src/show.jl

@@ -3,7 +3,7 @@ import Base: show
 const indent_spaces = "  "
 
 function show(io::IO, card::AbstractDemoCard)
-    println(io, basename(card))
+    print(io, basename(card))
 end
 
 function show(io::IO, sec::DemoSection; level=1)
@@ -15,6 +15,7 @@ function show(io::IO, sec::DemoSection; level=1)
     foreach(sec.cards) do x
         print(io, repeat(indent_spaces, level))
         show(io, x)
+        println(io)
     end
 
     foreach(x->show(io, x; level=level+1), sec.subsections)

src/types/card.jl

@@ -18,7 +18,6 @@ to your demofile. Currently supported types are:
 
 """
 function democard(path::String)::AbstractDemoCard
-    validate_file(path)
     _, ext = splitext(path)
     if ext in markdown_exts
         return MarkdownDemoCard(path)

src/types/julia.jl

@@ -74,6 +74,20 @@ mutable struct JuliaDemoCard <: AbstractDemoCard
     date::DateTime
     julia::VersionNumber
     hidden::Bool
+    function JuliaDemoCard(
+        path::String,
+        cover::Union{String, Nothing},
+        id::String,
+        title::String,
+        description::String,
+        author::String,
+        date::DateTime,
+        julia::VersionNumber,
+        hidden::Bool
+    )
+        isfile(path) || throw(ArgumentError("$(path) is not a valid file"))
+        new(path, cover, id, title, description, author, date, julia, hidden)
+    end
 end
 
 function JuliaDemoCard(path::String)::JuliaDemoCard

src/types/markdown.jl

@@ -67,6 +67,19 @@ mutable struct MarkdownDemoCard <: AbstractDemoCard
     author::String
     date::DateTime
     hidden::Bool
+    function MarkdownDemoCard(
+        path::String,
+        cover::Union{String, Nothing},
+        id::String,
+        title::String,
+        description::String,
+        author::String,
+        date::DateTime,
+        hidden::Bool
+    )
+        isfile(path) || throw(ArgumentError("$(path) is not a valid file"))
+        new(path, cover, id, title, description, author, date, hidden)
+    end
 end
 
 function MarkdownDemoCard(path::String)::MarkdownDemoCard

src/utils.jl

@@ -1,9 +1,3 @@
-function validate_file(path, filetype = :text)
-    isfile(path) || throw(ArgumentError("$(path) is not a valid file"))
-    check_ext(path, filetype)
-end
-
-
 function check_ext(path, filetype = :text)
     _, ext = splitext(path)
     if filetype == :text
@@ -19,6 +13,7 @@ end
 ### common utils for DemoPage and DemoSection
 
 function validate_order(order::AbstractArray, x::Union{DemoPage, DemoSection})
+    length(unique(order)) == length(order) || throw(ArgumentError("`\"order\"` entry should be unique."))
     default_order = get_default_order(x)
     if intersect(order, default_order) == union(order, default_order)
         return true