talk: finish pres and yt script

2026-01-30 14:24:52 -06:00
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+---
+title: A Trick for Designing Friendly APIs in Go
+theme: default
+layout: center
+class: text-center
+fonts:
+  sans: "CaskaydiaCove Nerd Font Mono"
+---
+
+# Why I love control flow in C#
+
+---
+layout: center
+class: text-center
+---
+
+# The false dichotomy
+
+<div class="grid grid-cols-2 gap-12 mt-16 text-left">
+    <v-click>
+        <div class="border-l-4 border-red-500 pl-6">
+            <h3 class="text-red-400 text-2xl font-bold mb-2">Team "Never Throw"</h3>
+            <p class="text-gray-400">"Exceptions are expensive! Treat errors as values! Not every failure is exceptional!"</p>
+        </div>
+    </v-click>
+    <v-click>
+        <div class="border-l-4 border-blue-500 pl-6">
+            <h3 class="text-blue-400 text-2xl font-bold mb-2">Team "Always Throw"</h3>
+            <p class="text-gray-400">"Results are noisy! Just throw and let the middleware handle it! Keep the code clean!"</p>
+        </div>
+    </v-click>
+</div>
+<v-click>
+    <div class="mt-16 text-2xl text-green-400">
+    > Why not both?
+    </div>
+</v-click>
+
+---
+layout: center
+---
+
+# The sweet spot
+
+<div class="grid grid-cols-4 gap-4 mt-8 h-full">
+    <v-click>
+        <div class="bg-gray-800 p-4 rounded border-t-4 border-red-500">
+            <div class="font-bold mb-2 text-center">Global Handler</div>
+            <div class="text-sm text-center">Prevent crashes</div>
+        </div>
+    </v-click>
+    <v-click>
+        <div class="bg-gray-800 p-4 rounded border-t-4 border-green-500">
+            <div class="font-bold mb-2 text-center">Controller</div>
+            <div class="text-sm text-center">Matches result</div>
+        </div>
+    </v-click>
+    <v-click>
+        <div class="bg-gray-800 p-4 rounded border-t-4 border-blue-500">
+            <div class="font-bold mb-2 text-center">Service Layer</div>
+            <div class="text-sm text-center">Returns results</div>
+        </div>
+    </v-click>
+    <v-click>
+        <div class="bg-gray-800 p-4 rounded border-t-4 border-purple-500">
+            <div class="font-bold mb-2 text-center">Deep / Domain</div>
+            <div class="text-sm text-center">Throws exceptions</div>
+        </div>
+    </v-click>
+</div>
+
+---
+layout: center
+---
+
+# An example in a web API
+
+---
+layout: center
+---
+
+# Use exceptions for context agnostic code
+
+```csharp
+public async Task<User?> GetUserAsync(int userId)
+{
+    // NOTE: EF Core might throw exceptions for connection issues, etc.
+    var user = await _dbContext.Users.FindAsync(userId);
+
+    // NOTE: Domain logic might throw exceptions for business rules
+    if (user?.IsBanned)
+    {
+        throw new UserBannedException(userId);
+    }
+
+    return user;
+}
+```
+
+---
+
+# Service layer returns results
+
+```csharp
+public async Task<Result<User>> GetUserAsync(int userId)
+{
+    try
+    {
+        var user = await _userService.GetUserAsync(userId);
+
+        if (user is null)
+        {
+            return Result.Failure<User>(new UserNotFoundException(userId));
+        }
+
+        return Result.Success(user);
+    }
+    catch (UserBannedException ex)
+    {
+        return Result.Failure<User>(ex);
+    }
+}
+```
+
+---
+
+# Match results in the controller
+
+```csharp
+public static async Task<IResult> GetUserHandler(int userId, IUserService _service)
+{
+    var result = await _service.GetUserAsync(userId);
+
+    return result.Match(
+        user => Ok(user),
+        error => error switch
+        {
+            UserNotFoundException => Results.NotFound(),
+            UserBannedException => Results.Forbid(),
+            _ => Results.InternalServerError()
+        }
+    );
+}
+```
+
+---
+
+# Global handler for unexpected errors
+
+```csharp
+public async ValueTask<bool> TryHandleAsync(
+    HttpContext httpContext,
+    Exception exception,
+    CancellationToken cancellationToken
+)
+{
+    _logger.LogError(
+        exception,
+        "Exception occurred: {Message}", exception.Message
+    );
+
+    httpContext.Response.StatusCode =
+        StatusCodes.Status500InternalServerError;
+
+    await httpContext.Response
+        .WriteAsync("An unexpected error occurred.", cancellationToken);
+
+    return true;
+}
+```
+
+---
+layout: center
+---
+
+# C# gives me the freedom to choose
+
+<ul>
+    <v-click>
+        <li>Use exceptions when deep in the call stack.</li>
+    </v-click>
+    <v-click>
+        <li>Use result types where business logic is centralized.</li>
+    </v-click>
+    <v-click>
+        <li>Use global handlers for unexpected exceptions and to prevent crashes.</li>
+    </v-click>
+</ul>