Remove memoization from index name

[mikeyhogarth]

Simple change but maybe one that needs some discussion. The reason for making this change is that the value that needs to be assigned to @index_name may change between calls to index_name, such as between requests in multitenant environment.

If for example the default_prefix were set to a lambda or were overridden to be something dynamic, it wouldn't be re-initialised between requests.

We can sort this out by just not memoizing that variable, however this does introduce a performance overhead (it'll re-evaluate the regex/demodulize etc. every time and will create a new variable) however I think this overhead is very minor compared to the benefit.

If you'd prefer not to have the overhead at all I could introduce this as a configurable option (dynamic_index_names: true or something) but then that's maybe a step too far.

[mikeyhogarth]

Hmm this appears to cause other tests in the test suite to fail :(

@pyromaniac do you know if the memoization here (not being able to change the non-suggested index name after it's been set once) is desired functionality? The fact that I've broke the test suite by removing memoization would suggest so

[pyromaniac]

Well, if we are going to remove memoization, we have to get rid of instance variables completely. Also we have to extract name.sub(/Index\Z/, '').demodulize.underscore and similar statements to memoize them separately.

[pyromaniac]

But I'm ok with memoization removement

[pyromaniac]

Hey man! Are you going to update this? I would like to merge this PR

[pyromaniac]

In master already