Shopping cart performance enhancements

[lat9]

Reformatting

• Use null coalescing (??) operator where indicated
• Use short array syntax
• No one-line conditionals
• No one-line multiple assignments

Refactoring

• Since the contents property is keyed on a 'uprid', change the $products_id key to be $uprid on foreach traversals of that array. That makes it more obvious when viewing the code as to what the contents array is keyed on.
• Limit MySQL updates to a single row for unique operations.
• Use === where warranted.
• Use zen_define_default where warranted.
• Use strpos instead of preg_match when checking for gift-certificates in the cart.
• Remove redundant code.
• Use zen_get_product_details where warranted to get maximum cached queries. Results in a roughly 50% reduction in time taken to add/remove/update a product as well as the cart's overall calculations!

Corrections

• calculate didn't process a 'base' product pricing if a product wasn't found, but did process the attributes! Should the product be removed from the cart if this condition is found?

[lat9]

FWIW, I'm also considering removing the use of $display_debug_messages; is anyone actually using this? There are many better ways to debug the shopping-cart actions.

[drbyte]

FWIW, I'm also considering removing the use of $display_debug_messages; is anyone actually using this? There are many better ways to debug the shopping-cart actions.

I've only used it a few times, but it was certainly helpful at the time.

If the class had more smaller methods in it it would be even easier to debug when a problem occurred, instead of having to trace through to figure out which block is doing what ... which that $display_debug_messages var was trying to help with, IIRC.

[lat9]

Agreed on the smaller methods. If the feature has utility, it stays!

[drbyte]

Oy, this is a massive bunch of changes in one commit. Super complex to review. 😨

[drbyte]

Looks great. Thanks. That's a huge overhaul, optimizing a ton of things.

A couple small bugs highlighted.

Brings back memories of when a bunch of this code was written ... ... shaking my head :D

[lat9]

I believe that I've got all the corrections/comments addressed in the just-pushed update.

[torvista]

If you set
declare(strict_types=1);
to the start of this file, and add a product to the cart, it dies/spits out a series of errors due to mismatched casting.

[lat9]

Thanks, @torvista. I'll address that in the changes associated with #6017, since the shopping_cart class requires updates there as well.

[torvista]

There's only 12 errors, but some may generate a "big-picture" discussion, so it may be prudent to hoist it above the parapet as a separate thing to throw mud at, in the interests of mixing metaphors.