From: Charles McGarvey <cmcgarvey@bluehost.com>
Date: Sun, 17 Jun 2018 21:39:38 +0000 (-0600)
Subject: add slides on exception handling
X-Git-Url: https://git.dogcows.com/gitweb?p=chaz%2Ftalk-event-driven-programming-in-perl;a=commitdiff_plain;h=fa698f7b8f498a04b0394f5cadc2cadf0a6fb21a

add slides on exception handling
---

diff --git a/css/slides.css b/css/slides.css
index 93fa174..abeeb12 100644
--- a/css/slides.css
+++ b/css/slides.css
@@ -10,7 +10,6 @@
     width: 100%;
 }
 
-
 .pizza img {
     width: 70%;
 }
@@ -53,3 +52,11 @@
     font-size: 32px;
 }
 
+#slide-not-all-roses img {
+    width: 70%;
+}
+
+.ex-exceptions .perl {
+    font-size: 38px;
+}
+
diff --git a/img/thorn.jpg b/img/thorn.jpg
new file mode 100644
index 0000000..4c7be52
Binary files /dev/null and b/img/thorn.jpg differ
diff --git a/notes.txt b/notes.txt
index 16f2f5c..0d32c72 100644
--- a/notes.txt
+++ b/notes.txt
@@ -30,6 +30,7 @@ X kernel facilities (poll, select, etc.)
 - Exceptions in event-driven code.
 - SIGPIPE, EPIPE - might have more to do with long-lived processes rather than
   just event-driven programming, but still something to watch out for...
+- You should almost always check the return code of your syscalls to see if they succeeded or not.
 
 7. Promises:
 - Future
@@ -51,6 +52,7 @@ X What is event-driven programming?
 - C10k problem
 - EDA (event-driven architecture)
 - Benefits of Event-driven
+- How to debug event-driven code.
 
 Traditional programs:
 - CGI - web server calls your program, and your program does its thing and
diff --git a/slides.html b/slides.html
index d86ee03..6d589b4 100644
--- a/slides.html
+++ b/slides.html
@@ -445,6 +445,56 @@ while (1) {
 - [`Mojo::Reactor::Poll`](https://metacpan.org/source/Mojo::Reactor::Poll)
 ]
 
+---
+name:  not-all-roses
+class: center, middle
+
+![Thorns](img/thorn.jpg)
+
+## Watch out for the thorns...
+
+???
+There are some special considerations you need to take when writing event-driven code.
+
+---
+class: center, middle
+
+## Exceptions for error handling
+
+---
+class: center, middle
+
+### Problem: No exception handler up the call stack
+
+---
+class: ex-exceptions
+
+## Rule: Don't die/throw in event handlers.
+
+--
+### Error callback pattern
+
+```perl
+do_something_asynchronously(
+    callback => sub { ... },
+    on_error => sub { ... },
+);
+```
+
+---
+class: ex-exceptions
+
+## Rule: Don't die/throw in event handlers.
+
+### Use promises
+
+```perl
+my $promise = do_something_asynchronously();
+
+$promise->on_done(sub { ... });
+$promise->on_fail(sub { ... });
+```
+
 ---
 class: center, middle