From a51872fb823013c98aacde5f072aeaa5a6ce5f38 Mon Sep 17 00:00:00 2001
From: Logan Darklock <logandarklock@gmail.com>
Date: Fri, 22 Jan 2021 16:33:07 -0800
Subject: [PATCH 1/2] Implement builder pattern; fixes #10

---
 Cargo.toml    |  1 +
 src/config.rs | 13 ++++++++++++-
 src/lib.rs    |  4 +++-
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index bbc0f52..c6255df 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,3 +15,4 @@ readme = "README.md"
 glutin = "0.26.0"
 gl = "0.10.0"
 rustic_gl = "0.3.2"
+derive_builder = "0.10.0-alpha"
diff --git a/src/config.rs b/src/config.rs
index 2aa186a..e9e11f1 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -20,9 +20,20 @@ use glutin::dpi::LogicalSize;
 /// from a trait like [`Default`]. The [`config!`][config] macro makes it much less tedious to
 /// construct custom configs. See its documentation for more information.
 ///
+/// Alternatively, you can choose to use the builder pattern instead:
+///
+/// ```
+/// use mini_gl_fb::ConfigBuilder;
+///
+/// let config = ConfigBuilder::default()
+///     .invert_y(false)
+///     .build().unwrap();
+/// ```
+///
 /// If there's a config option you want to see or think is missing, please open an issue!
 #[non_exhaustive]
-#[derive(Clone, PartialEq, Debug)]
+#[builder(default)]
+#[derive(Clone, PartialEq, Debug, Builder)]
 pub struct Config {
     /// Sets the pixel dimensions of the buffer. The buffer will automatically stretch to fill the
     /// whole window. By default this will be the same as the window_size.
diff --git a/src/lib.rs b/src/lib.rs
index 41e3857..1f1e7a4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -105,6 +105,8 @@
 
 #[macro_use]
 pub extern crate rustic_gl;
+#[macro_use]
+extern crate derive_builder;
 
 pub extern crate glutin;
 pub extern crate gl;
@@ -114,7 +116,7 @@ pub mod core;
 pub mod breakout;
 
 pub use breakout::{GlutinBreakout, BasicInput};
-pub use config::Config;
+pub use config::{Config, ConfigBuilder};
 pub use core::{Internal, BufferFormat, Framebuffer};
 
 use core::ToGlType;

From 3a91ef772d3ff10e0aa2e116c03d1b9ba2692942 Mon Sep 17 00:00:00 2001
From: Logan Darklock <logandarklock@gmail.com>
Date: Fri, 22 Jan 2021 16:45:11 -0800
Subject: [PATCH 2/2] Building a Config cannot fail

---
 src/config.rs | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/config.rs b/src/config.rs
index e9e11f1..603ba85 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -27,12 +27,13 @@ use glutin::dpi::LogicalSize;
 ///
 /// let config = ConfigBuilder::default()
 ///     .invert_y(false)
-///     .build().unwrap();
+///     .build();
 /// ```
 ///
 /// If there's a config option you want to see or think is missing, please open an issue!
 #[non_exhaustive]
 #[builder(default)]
+#[builder(build_fn(skip))]
 #[derive(Clone, PartialEq, Debug, Builder)]
 pub struct Config {
     /// Sets the pixel dimensions of the buffer. The buffer will automatically stretch to fill the
@@ -54,6 +55,28 @@ pub struct Config {
     pub invert_y: bool
 }
 
+impl ConfigBuilder {
+    /// Builds a new [`Config`].
+    pub fn build(&self) -> Config {
+        let mut config = Config::default();
+
+        macro_rules! fields {
+            ($($n:ident),+) => {
+                $(
+                if let Some($n) = &self.$n {
+                    config.$n = $n.clone();
+                }
+                )+
+            }
+        }
+
+        // I guess this is better than implementing the entire builder by hand
+        fields!(buffer_size, resizable, window_title, window_size, invert_y);
+
+        config
+    }
+}
+
 impl Default for Config {
     fn default() -> Self {
         Config {