From edce20642b6d177ee9877775cbfa9e05ebb4e404 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Tue, 2 Aug 2022 23:31:21 +0200
Subject: Replace maybe_make.

It seems unnecessary to throw exceptions when simply checking whether
a library exists.
---
 c/common.cpp | 10 ++++++++++
 c/common.h   | 21 ++-------------------
 c/main.cpp   |  9 +++++----
 3 files changed, 17 insertions(+), 23 deletions(-)

diff --git a/c/common.cpp b/c/common.cpp
index fcf1da2..5d786da 100644
--- a/c/common.cpp
+++ b/c/common.cpp
@@ -1,3 +1,4 @@
+#include <utility>
 #include <windows.h>
 
 #include "common.h"
@@ -104,6 +105,15 @@ const wchar_t* Win32Error::WhatW() const noexcept
 
 /* Library: Wrapper for loading and freeing dynamically linked libraries. */
 
+std::optional<Library> Library::Maybe(const wchar_t* const lib)
+{
+	HMODULE hModule = LoadLibrary(lib);
+	if (!hModule) return {};
+	return Library(hModule);
+}
+
+Library::Library(const HMODULE hModule) : m_hModule(hModule) {}
+
 Library::Library(const wchar_t* const lib)
 {
 	m_hModule = LoadLibrary(lib);
diff --git a/c/common.h b/c/common.h
index d908d12..0851bb6 100644
--- a/c/common.h
+++ b/c/common.h
@@ -5,12 +5,6 @@
 #include <optional>
 #include <windows.h>
 
-#ifdef UNICODE
-#define WA "W"
-#else
-#define WA "A"
-#endif
-
 int EBMessageBox(const wchar_t* wszText, const wchar_t* wszCaption, unsigned uType);
 int GetRelativeCursorPos(HWND hWnd, POINT* pt);
 
@@ -46,10 +40,12 @@ private:
 
 struct Library
 {
+	static std::optional<Library> Maybe(const wchar_t* lib);
 	Library(const wchar_t* lib);
 	~Library();
 	template <class T> T* GetProcAddress(const char* szProc);
 private:
+	Library(HMODULE hModule);
 	HMODULE m_hModule;
 };
 
@@ -65,19 +61,6 @@ inline int wszf(wchar_t (&buf)[N], const wchar_t* const fmt, T... xs)
 	return _snwprintf_s(buf, N, _TRUNCATE, fmt, xs...);
 }
 
-/* Create and return an object of type C. If construction fails,
- * return nothing. The returned value must be checked before being
- * used, as dereferencing is undefined if the value is empty. */
-template <typename T, typename... U>
-std::optional<T> maybe_make(U... xs)
-{
-	try {
-		return T(xs...);
-	} catch (...) {
-		return {};
-	}
-}
-
 /* Variable template for caching values from GetSystemMetrics. */
 template <int I>
 auto Metric = GetSystemMetrics(I);
diff --git a/c/main.cpp b/c/main.cpp
index d76225e..32187c8 100644
--- a/c/main.cpp
+++ b/c/main.cpp
@@ -1,4 +1,5 @@
 #include <exception>
+#include <stdexcept>
 #include <windows.h>
 #include <commctrl.h>
 #include <uxtheme.h>
@@ -165,16 +166,16 @@ static LRESULT CALLBACK CBTProc(const int nCode, const WPARAM wParam, const LPAR
 	g_hWnd = (HWND)wParam;
 
 	/* Look up constants. */
-	if (auto lib = maybe_make<Library>(L"User32.dll");
+	if (auto lib = Library::Maybe(L"User32.dll");
 	    auto GetDpiForWindow = lib->GetProcAddress<UINT(HWND)>("GetDpiForWindow"))
 		g_dpi = GetDpiForWindow(g_hWnd);
 
-	if (auto lib = maybe_make<Library>(L"uxtheme.dll");
+	if (auto lib = Library::Maybe(L"uxtheme.dll");
 	    lib->GetProcAddress<void>("SetWindowTheme"))
 		g_bThemes = 1;
 
-	if (auto lib = maybe_make<Library>(L"User32.dll");
-	    lib->GetProcAddress<void>("SystemParametersInfo" WA)) {
+	if (auto lib = Library::Maybe(L"User32.dll");
+	    lib->GetProcAddress<void>("SystemParametersInfoW")) {
 		NONCLIENTMETRICS m;
 		m.cbSize = sizeof(NONCLIENTMETRICS);
 		require(SystemParametersInfo(SPI_GETNONCLIENTMETRICS,
-- 
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