X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=slides%2Fcaesar-encipher.html;h=4ef1d341125d73a444a6d2cbbc01a7e7dce08c7c;hb=b2bff955d11597f85c5e1935165a44fb0e5e487e;hp=1cdf8ddf0ad3cc22da75e10f27385c2f569ce118;hpb=2c871791002cd822e2e6d8a81c9728049d66c2c1;p=cipher-training.git
diff --git a/slides/caesar-encipher.html b/slides/caesar-encipher.html
index 1cdf8dd..4ef1d34 100644
--- a/slides/caesar-encipher.html
+++ b/slides/caesar-encipher.html
@@ -1,7 +1,7 @@
- Title
+ Caesar cipher
@@ -35,7 +51,34 @@
-* Letter-by-letter enciphering
+Letter-by-letter enciphering
+
+---
+
+layout: true
+
+.indexlink[[Index](index.html)]
+
+---
+
+# Enciphering and deciphering
+
+## Arithmetic on letters
+
+Convert .plaintext[letter] â .plaintext[number] â
+.ciphertext[number] â .ciphertext[letter]
+
+Functions you will need
+
+```python
+ord()
+
+chr()
+
+%
+```
+
+* What are good test cases?
---
@@ -43,6 +86,7 @@
```python
import string
+
string.ascii_letters
string.ascii_lowercase
string.ascii_uppercase
@@ -50,6 +94,11 @@ string.digits
string.punctuation
```
+---
+# DRY and YAGNI
+
+Is your code DRY?
+
---
# Doctest
@@ -57,6 +106,19 @@ string.punctuation
* Why document?
* Why test?
+```python
+def caesar_encipher_letter(letter, shift):
+ """Encipher a letter, given a shift amount
+
+ >>> caesar_encipher_letter('a', 1)
+ 'b'
+ """
+ if letter in string.ascii_letters:
+ .
+ .
+ .
+```
+
---
# The magic doctest incantation
@@ -71,6 +133,17 @@ if __name__ == "__main__":
# Doing all the letters
+## Test-first developement
+
+1. Write the tests.
+ * They will fail. There is no code.
+2. Write code until the tests pass.
+3. Refactor.
+
+---
+
+# Doing all the letters
+
## Abysmal
```python
@@ -83,7 +156,7 @@ for i in range(len(plaintext)):
# Doing all the letters
-## (Merely) Bad
+## Bad
```python
ciphertext = ''
@@ -91,6 +164,8 @@ for p in plaintext:
ciphertext += caesar_encipher_letter(p, key)
```
+...but easily generalisable
+
---
# Doing all the letters
@@ -98,8 +173,7 @@ for p in plaintext:
## Good (but unPythonic)
```python
-ciphertext = map(lambda p: caesar_encipher_letter(p, key),
- plaintext)
+ciphertext = map(lambda p: caesar_encipher_letter(p, key), plaintext)
```
---
@@ -109,16 +183,21 @@ ciphertext = map(lambda p: caesar_encipher_letter(p, key),
## Best
```python
-ciphertext = [caesar_encipher_letter(p, key)
- for p in plaintext]
+ciphertext = [caesar_encipher_letter(p, key) for p in plaintext]
```
+---
+
+# Not all iterables are equal
+```python
+''.join()
+```
\ No newline at end of file