Have the ability to insert major, minor and revision constants into source files.

[dpcollins-google]

It should be possible to access the version of a library in code. Currently this is (afaik) only possible in java with https://googleapis.dev/java/gax/latest/com/google/api/gax/core/GaxProperties.html#getLibraryVersion-java.lang.Class-, which reaches into the maven metadata to do so.

It would be useful to be able to paste MAJOR_VERSION = x MINOR_VERSION = y, REVISION = z constants in each language, or even just the numbers representing them by regex substitution into source files upon release.

[bcoe]

@dpcollins-google the way folks tend to do this in the Node.js community is to require('package.json'), as Node.js allows you to require JSON, and the version is in the package.json file.

I'd would be curious to know the best way to approach this for Python, happy to add language specific stuff like this.

[chingor13]

We now support an extraFiles option which, for Java, will do it's standard version replacements (via those special comment annotations) in arbitrary files configured. Here's an example in the Bigtable repo: https://github.com/googleapis/java-bigtable/pull/715/files#diff-35de1d9d9feb5d407dc0e1ca40e9490c335cdd441607bdaf49f8c1bb0a5e0c7d

For other languages, we would want something similar - a generic way to mark what versions need to be updated.

[chingor13]

Note: code search is a very expensive API call, so we cannot be consistently searching across all the source for a variety of patterns. Since the source file will likely differ from project to project, a configurable list of extra files to consider seems reasonable.

[chingor13]

Also related to #305