DDC-3481: [GH-1241] [3.0] [POC] lazy-load on a per-property base

[doctrinebot]

Jira issue originally created by user @doctrinebot:

This issue is created automatically through a Github pull request on behalf of Ocramius:

Url: #1241

Message:

This is just a proof of concept that I hacked together real quick.

This changes how proxies are generated and lazy-loaded in a very radical way:

• method calls do not cause lazy-loading
• lazy-loading is triggered by access to non-transient properties (things that need to be lazy-loaded)
• access to identifiers or non-mapped properties won't cause lazy-loading

Following BC breaks need to be fixed or discussed before going forward on this idea:

• proxies don't implement Doctrine\Common\Proxy\Proxy anymore, but ProxyManager\Proxy\GhostObjectInterface (BC break, needs fixing, can be easily done with some effort)
• serialize($proxy) now causes proxy initialization (probably needs fixing, as this is a major BC break)

Pending TODOs:

• cloning a proxy is still not fully supported (requires dedicated logic in **clone)
• this is just a PoC, so the code that writes proxies to disk is not yet in place

[doctrinebot]

• is referenced by DCOM-282: Use call_user_func_array in proxy classes

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-1241] was labeled:
#1241

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-1241] was labeled:
#1241