Lazy loading model for module imports

[rhubner]

This PR fixes #1848 by allowing the user to configure which modules should be loaded lazily.

It adds a new attribute load on the module element of conf.xml. If unspecified, modules are loaded automatically (i.e. eagerly) to maintain backwards compatibility with the previous eXist-db mode of operation.

The exist-distribution config file was updated to take advantage of this new feature. Only those modules that are deemed as required by eXist-db's XQSuite tests and Apps are loaded by default. Other modules can be loaded with import module namespace, for example:

import module namespace validation = "http://exist-db.org/xquery/validation";

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This open source contribution to the eXist-db project was commissioned by the Office of the Historian, U.S. Department of State, https://history.state.gov/.

[sonarqubecloud]

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[dizzzz]

Great work! Being non-native, I find the term "lazily" quite hard to remember, I think I see "lazy" more often, is shorter and IMO more clear whilst still correct?

[dizzzz]

interesting change.....

[dizzzz]

Great work! @adamretter are we completely sure that the code is backwards compatible? This line might show something different? (not sure)

is this PR a v7 candidate ? will old code still work?

[adamretter]

Great work! Being non-native, I find the term "lazily" quite hard to remember, I think I see "lazy" more often, is shorter and IMO more clear whilst still correct?

@dizzzz "lazily" is the adverb (modifies a verb), whilst "lazy" is the adjective (describes a state).

In this instance load="lazily" - so the verb is "load", and the adverb ("lazily") modifies that.

I think it makes sense, although for sure my English is not perfect either!

We can change it if you still want us to? Perhaps @joewiz has an opinion on this?

[joewiz]

I see benefits in standardizing on "lazy". Now the code has instances of both "lazy" and "lazily" (but only "eager" - not "eagerly" - instead "always"). Standardizing on just "lazy" and "eager" (and doing away with "lazily" and "always") would probably prevent people mixing up the different verb forms/words on their code/configurations.

[line-o]

This change is a clear hint that this constitutes a breaking change.
Library and main modules that use one of the functions in the inspect namespace will no longer function until they are imported.

[line-o]

If I understand this PR correctly each module with load=lazy needs to imported explicitly in any module that wants to use them. Looking at the list where this is applied - like lucene, http-client, security-manager to name a few - this will create a lot of work on any library and app that is doing a little more than showing static content.
I believe we need to discuss the modules that are lazy-loaded by default.
For this to be merged into 6.x.x my answer would be: none.

[adamretter]

LGTM

[adamretter]

Standardizing on just "lazy" and "eager"

@joewiz We have now switched this to lazy and eager

[adamretter]

This change is a clear hint that this constitutes a breaking change.

@line-o Sure, the target for this is eXist-db 7.0.0.

[sonarqubecloud]

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[line-o]

Tests are failing

[sonarqubecloud]

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[duncdrum]

We should not lazily omit the documentation that shows the new need for explicit import, that makes this a major release candidate.

Should also be rebased to get some fresh ci results