[usdGenSchema] Header guard for schemaClass.h should have corresponding #endif in same file rather than being encoded in usdGenSchema.py logic

[moddyz]

Description of Issue

The #ifndef ... #define header guard started in codegenTemplates/schemaClass.h should have a corresponding #endif at the end of the same file. Currently, that #endif is added by usdGenSchema.py.

The use case is we prefer using #pragma once as the header guarding mechanism throughout our codebase. It would be useful to be able to make this customisation purely through codegenTemplates.

System Information (OS, Hardware)

ubuntu-18.04

Package Versions

usd-19.11

[jilliene]

Filed as internal issue #USD-5806

[spiffmon]

Hi @moddyz !
Moving the "terminator" logic entirely out of usdGenSchema and into schemaClass.h templates would require the addition of a new line/token to robustly bracket the custom section... and I think you might also lose the ability to add free functions. But most importantly, the implication is that it would cause a diff to every single generated schema header, which is a pretty high overhead to accommodate this need.
However, we would support a PR that adds a command-line option to usdGenSchema , --headerTerminatorString so that you are not stuck with the hardcoded string that's in there, now, when generating your local schemas. You may want to add a companion argument that customizes the message that accompanies the --(BEGIN CUSTOM CODE)-- so that your users aren't still admonished to "Close the include guard with #endif"

[moddyz]

@spiffmon sounds like a solid plan 👍