Support ternary substitution in WithProperties

[jaredgrubb]

I think it would be nice to have support for "if (prop) then substitute X else substitute Y".

Python supports back-references in a regex, so I'm imagining that a possible syntax would be:

:? + delimiter + true_substitution + delimiter + false_substitution

For example:

• %(prop:?:sub_true:sub_false)s
• %(prop:?|sub_true|sub_false)s
• %(prop:?Asub_trueAsub_false)s

I'm not sure if ":?" would check the property based on existence (i.e. as ":+" does) or on true-ness (i.e. as ":~" does), or whether it would be nice to support both options?

[dustin]

I don't think Python's regex syntax is relevant, but this is a great idea. Probably different introductory characters should be used to make the distinction?

Will you be able to work on this?

[jaredgrubb]

The regex comment was that this could easily be implemented in regex like the others since Python supports back-references.

As for the existence vs trueness distinction, one idea I had was to borrow "#" from printf's "alternate format" modifier. So:

• ":?" means if prop exists
• ":#?" means if prop is true

And then another idea is that you could add ":#+" as an alias for ":~"; I personally have trouble telling ~ and - apart in font.

The other alternative is to just add another character: ":?" vs ":!".

Any preferences?

I could do this; it's a pretty easy patch.

[dustin]

I like the additional-character idea, including the alias. ~ and - are pretty difficult to distinguish, and I certainly don't remember which is which without looking it up!

[jaredgrubb]

I have a patch ready for this.

[Jared Grubb]

Fixes #2165: Add 'ternary' interpolation for WithProperties?

Changeset: d2bc38106ddfcc9e1aa0a892a5632d4d1fe2f417

[Dustin J. Mitchell]

Merge branch 'ternary-interpolation' of  git://github.com/jaredgrubb/buildbot

• 'ternary-interpolation' of  git://github.com/jaredgrubb/buildbot: ternary-sub: add docs Fixes #2165: Add 'ternary' interpolation for WithProperties? Changeset: 5cf757d57f5bc1c42c197c29adb4099f899663e0

[Tom Prince]

Revert "Fixes #2165: Add 'ternary' interpolation for WithProperties?"

This reverts commit d2bc38106ddfcc9e1aa0a892a5632d4d1fe2f417.

Changeset: a7fbe09d7d544692496f4bd91631f380e20927ce

[Tom Prince]

Revert "Fixes #2165: Add 'ternary' interpolation for WithProperties?"

This reverts commit d2bc38106ddfcc9e1aa0a892a5632d4d1fe2f417.

Changeset: a7fbe09d7d544692496f4bd91631f380e20927ce

[Tom Prince]

Revert "Fixes #2165: Add 'ternary' interpolation for WithProperties?"

This reverts commit d2bc38106ddfcc9e1aa0a892a5632d4d1fe2f417.

Changeset: a7fbe09d7d544692496f4bd91631f380e20927ce