#!/usr/bin/env python
# coding: utf-8

# This is a work-in-progress for some future cohpy meeting.

# Lastly, uses names to refer to parts of a string that match a regular expression is fantastic!  It makes the code much more readable than using meaningless numerical indexes.
# 
# This was new to a Python expert who now loves it,
# although his still prefers to eschew regular expressions
# because they are hard to read.
# 
# Imagine the following contrived example,
# where I want to get the hash of an git object from its filepath.

# In[1]:


s = '.git/objects/8e/28241360c472576e8caa944253d4af368d9081'

import re
git_pattern = re.compile(r'''
    .*/                      # anything and a slash
    (
        ([0-9a-fA-F]{2})     # 2 hexadecimal digits
        /                    # separated by a slash
        ([0-9a-fA-F]{38})    # 38 hexadecimal digits
    )$''', flags=re.VERBOSE)


# In[2]:


m = git_pattern.match(s)
m


# In[3]:


m.group(0)


# In[4]:


m.group(1)


# In[5]:


m.group(2)


# In[6]:


m.group(3)


# In[7]:


help(re.compile)


# In[8]:


s = '.git/objects/8e/28241360c472576e8caa944253d4af368d9081'

import re
git_pattern = re.compile(r'''
    .*/                      # anything and a slash
    (?P<hash_with_slash>
        (?P<hash_directory> [0-9a-fA-F]{2})     # 2 hexadecimal digits
        /                    # separated by a slash
        (?P<hash_filename> [0-9a-fA-F]{38})    # 38 hexadecimal digits
    )$''', flags=re.VERBOSE)


# In[9]:


m = git_pattern.match(s)
m


# In[10]:


m.group(2)


# In[11]:


m.group('hash_directory')


# In[12]:


m.group(3)


# In[13]:


m.group('hash_filename')


# In[14]:


hash = m.group('hash_directory') + m.group('hash_filename')
hash


# In[15]:


hash = ''.join(map(m.group, ('hash_directory', 'hash_filename')))
hash


# In[16]:


hash = ''.join(map(lambda s: m.group('hash_%s' % s), ('directory', 'filename')))
hash


# In[17]:


m.group(1)


# In[18]:


m.group('hash_with_slash')


# In[19]:


hash = ''.join(c for c in m.group('hash_with_slash') if c != '/')
hash


# In[20]:


s


# In[21]:


s = '8e/28241360c472576e8caa944253d4af368d9081'
m = git_pattern.match(s)
m


# In[22]:


repr(m)