add a new image for chap 13

Makefile

@@ -13,4 +13,4 @@ count-todos:
 	ls *.asciidoc | xargs grep -c TODO | sed  s/:/\\t/
 
 diagrams: html
-	./render-diagrams.py
+	./render-diagrams.py $(CHAP)

chapter_13_dependency_injection.asciidoc

@@ -231,30 +231,41 @@ Because Python is not a "pure" OO language, Python developers aren't necessarily
 used to the concept of needing to "compose" a set of objects into a working
 application.  We just pick our entrypoint and run code from top to bottom.],
 and we'll do a bit of "Manual DI" (dependency injection without a
-frameworkfootnote:[Mark Seeman calls this https://blog.ploeh.dk/2012/11/06/WhentouseaDIContainer/[Pure DI], or sometimes "Vanilla DI".]).
+frameworkfootnote:[Mark Seeman calls this https://blog.ploeh.dk/2012/11/06/WhentouseaDIContainer/[Pure DI], or sometimes "Vanilla DI".]),
+and it will all turn out something like <<bootstrap_diagram>>.
 
 
+[bootstrap_diagram]]
+.Bootstrapper between entrypoints and message bus
+image::images/apwp_1303.png[]
+[role="image-source"]
 ----
-Flask + Redis
-|
-| call
-V
-Bootstraper:  prepares handlers with correct dependencies injected in
-|             (test bootstrapper will use fakes, prod one will use reals)
-|
-|  pass injected handlers to
-V
-Messagebus
-|
-|  dispatches events and commands to injected handlers
-|
-V
+[ditaa, apwp_1303]
+
++---------------+
+|  Entrpyoints  |
+| (Flask/Redis) |
++---------------+
+        |
+        | call
+        V
+ /--------------\
+ |              |  prepares handlers with correct dependencies injected in
+ | Bootstrapper |  (test bootstrapper will use fakes, prod one will use real)
+ |              |
+ \--------------/
+        |
+        | pass injected handlers to
+        V
+/---------------\
+|  Message Bus  |
++---------------+
+        |
+        | dispatches events and commands to injected handlers
+        |
+        V
 ----
 
-TODO: betterify diagram? or just get rid of, in favour of the first?
-
-
-
 
 === Preparing Handlers: Manual DI with Closures and Partials
 
@@ -745,7 +756,7 @@ of setup and sensible defaults into a single place.
 **********************************************************************
 Change all the handlers to being classes as per <<di_with_classes>>,
 and amend the bootstrapper's DI code as appropriate.  This will let you
-know if you prefer the functional or the class-based approach, when 
+know if you prefer the functional or the class-based approach, when
 it comes to your own projects.
 **********************************************************************
 
@@ -996,14 +1007,14 @@ And, erm, that's it really.
 
 There are two possible things you could do for practice regarding adapters:
 
-1. Try swapping out our notifications from email to, for example, SMS 
+1. Try swapping out our notifications from email to, for example, SMS
     notifications using Twilio, or Slack notifications.  Can you find
     a good equivalent to Mailhog for integration testing?
 
 2. In a similar way to what we did moving from `send_mail` to a `Notifications`
     class, try refactoring our `redis_eventpublisher` which is currently just
     a `Callable` to some sort of more formal adapter / base class / protocol.
-    
+
 ******************************************************************************
 
 

render-diagrams.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+import sys
 import tempfile
 import subprocess
 from pathlib import Path
@@ -7,16 +8,24 @@
 IMAGES_DIR = Path(__file__).absolute().parent / 'images'
 
 
-def main():
+def all_chapter_names():
     for fn in sorted(Path(__file__).absolute().parent.glob('*.html')):
         chapter_name = fn.name.replace('.html', '')
         if chapter_name == 'book':
             continue
-        print('Rendering images for', chapter_name)
+        yield chapter_name
+
+def main(paths):
+    if paths:
+        chapter_names = [p.replace('.html', '').replace('.asciidoc', '') for p in paths]
+    else:
+        chapter_names = all_chapter_names()
+    for chapter_name in chapter_names:
         render_images(chapter_name)
 
 
 def render_images(chapter_name):
+    print('Rendering images for', chapter_name)
     raw_contents = Path(f'{chapter_name}.html').read_text()
     parsed_html = html.fromstring(raw_contents)
 
@@ -68,4 +77,4 @@ def render_image(source, image_id):
 
 
 if __name__ == '__main__':
-    main()
+    main(sys.argv[1:])