X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=slides%2Fcaesar-encipher.html;h=4afd78dad4f3367c5107a99d0f40ff8f1e0aa037;hb=7203ac94911556e2b4bf4caab6f5285445faed3b;hp=f45a166ca80d71f37605364c4dac44c9e43925d1;hpb=7fc1274a02de18710febd4a1f7d89ba7eaea6192;p=cipher-training.git diff --git a/slides/caesar-encipher.html b/slides/caesar-encipher.html index f45a166..4afd78d 100644 --- a/slides/caesar-encipher.html +++ b/slides/caesar-encipher.html @@ -37,6 +37,11 @@ text-shadow: 0 0 20px #333; padding: 2px 5px; } + .indexlink { + position: absolute; + bottom: 1em; + left: 1em; + } @@ -50,6 +55,12 @@ Letter-by-letter enciphering --- +layout: true + +.indexlink[[Index](index.html)] + +--- + # Enciphering and deciphering ## Arithmetic on letters @@ -71,6 +82,34 @@ chr() --- +# 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? @@ -120,50 +160,7 @@ if __name__ == "__main__": --- -# Accents - -```python ->>> caesar_encipher_letter('é', 1) -``` -What does it produce? - -What should it produce? - -## Unicode, combining codepoints, and normal forms - -Text encodings will bite you when you least expect it. - -* urlencoding is the other pain point. - ---- - -# Five minutes on StackOverflow later... - -```python -def unaccent(text): - """Remove all accents from letters. - It does this by converting the unicode string to decomposed compatibility - form, dropping all the combining accents, then re-encoding the bytes. - - >>> unaccent('hello') - 'hello' - >>> unaccent('HELLO') - 'HELLO' - >>> unaccent('héllo') - 'hello' - >>> unaccent('héllö') - 'hello' - >>> unaccent('HÉLLÖ') - 'HELLO' - """ - return unicodedata.normalize('NFKD', text).\ - encode('ascii', 'ignore').\ - decode('utf-8') -``` - ---- - -# Doing all the letters +# Doing the whole message ## Test-first developement @@ -174,7 +171,7 @@ def unaccent(text): --- -# Doing all the letters +# Doing the whole message ## Abysmal @@ -184,9 +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 @@ -200,7 +199,7 @@ for p in plaintext: --- -# Doing all the letters +# Doing the whole message ## Good (but unPythonic) @@ -210,7 +209,7 @@ ciphertext = map(lambda p: caesar_encipher_letter(p, key), plaintext) --- -# Doing all the letters +# Doing the whole message ## Best