X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=slides%2Fcaesar-encipher.html;h=4afd78dad4f3367c5107a99d0f40ff8f1e0aa037;hb=7203ac94911556e2b4bf4caab6f5285445faed3b;hp=a4d5b2df15bbec0f783b85e6a2d2658314a32742;hpb=7722e2c6e5d07284cb324c2426c1fc7d47842120;p=cipher-training.git
diff --git a/slides/caesar-encipher.html b/slides/caesar-encipher.html
index a4d5b2d..4afd78d 100644
--- a/slides/caesar-encipher.html
+++ b/slides/caesar-encipher.html
@@ -1,7 +1,7 @@
- Title
+ Caesar cipher
@@ -50,6 +55,12 @@ Letter-by-letter enciphering
---
+layout: true
+
+.indexlink[[Index](index.html)]
+
+---
+
# Enciphering and deciphering
## Arithmetic on letters
@@ -64,13 +75,41 @@ ord()
chr()
-mod()
+%
```
* What are good test cases?
---
+# Using the tools
+
+Before doing anything, create a new branch in Git
+
+* This will keep your changes isolated
+
+Experiment in IPython (ephemeral, for us)
+
+Once you've got something working, copy the code into a `.py` file (permanent and reusable)
+
+```python
+from imp import reload
+
+import test
+reload(test)
+from test import *
+```
+
+Re-evaluate the second cell to reload the file into the IPython notebook
+
+When you've made progress, make a Git commit
+
+* Commit early and often!
+
+When you've finished, change back to `master` branch and `merge` the development branch
+
+---
+
# The [string module](http://docs.python.org/3.3/library/string.html) is your friend
```python
@@ -84,6 +123,7 @@ string.punctuation
```
---
+
# DRY and YAGNI
Is your code DRY?
@@ -103,37 +143,13 @@ def caesar_encipher_letter(letter, shift):
'b'
"""
if letter in string.ascii_letters:
+ .
+ .
+ .
```
---
-# My tests
-
-```python
-def caesar_encipher_letter(letter, shift):
- """Encipher a letter, given a shift amount
-
- >>> caesar_encipher_letter('a', 1)
- 'b'
- >>> caesar_encipher_letter('a', 2)
- 'c'
- >>> caesar_encipher_letter('b', 2)
- 'd'
- >>> caesar_encipher_letter('x', 2)
- 'z'
- >>> caesar_encipher_letter('y', 2)
- 'a'
- >>> caesar_encipher_letter('z', 2)
- 'b'
- >>> caesar_encipher_letter('z', -1)
- 'y'
- >>> caesar_encipher_letter('a', -1)
- 'z'
- """
- if letter in string.ascii_letters:
-```
----
-
# The magic doctest incantation
```python
@@ -144,7 +160,7 @@ if __name__ == "__main__":
---
-# Doing all the letters
+# Doing the whole message
## Test-first developement
@@ -155,7 +171,7 @@ if __name__ == "__main__":
---
-# Doing all the letters
+# Doing the whole message
## Abysmal
@@ -165,9 +181,11 @@ for i in range(len(plaintext)):
ciphertext += caesar_encipher_letter(plaintext[i], key)
```
+Try it in IPython
+
---
-# Doing all the letters
+# Doing the whole message
## Bad
@@ -177,9 +195,11 @@ for p in plaintext:
ciphertext += caesar_encipher_letter(p, key)
```
+...but easily generalisable
+
---
-# Doing all the letters
+# Doing the whole message
## Good (but unPythonic)
@@ -189,7 +209,7 @@ ciphertext = map(lambda p: caesar_encipher_letter(p, key), plaintext)
---
-# Doing all the letters
+# Doing the whole message
## Best
@@ -208,7 +228,7 @@ ciphertext = [caesar_encipher_letter(p, key) for p in plaintext]
\ No newline at end of file