Request static-imports on a CodeBlock

[ronshapiro]

It would be nice to be able to request a member to be statically imported when it's being added to a CodeBlock instead of assuming it will be and then later on in the JavaFile remembering to request it.

For example, in:

CodeBlock statement = 
    CodeBlock.builder().add("$T.checkNotNull($L)", Preconditions.class, reference)
        .requestStaticImport(Preconditions.class, "checkNotNull")
        .build();

If I end up adding this to a MethodSpec, then great, the JavaFile which includes it is aware of it. If multiple conflicting signatures request a static import, then JavaFile can disambiguate. in the same way it does for imports. If I never end up including it, then I don't end up emitting an unused import.

This might require a new identifier, maybe $M for a MemberSelect:

CodeBlock statement = 
    CodeBlock.builder().add(
        "$M($L)",
        MemberSelect.of(Preconditions.class, "checkNotNull", ImportPolicy.STATIC)
    .build();

[sormuras]

Your $M proposal reminds me of #317 and #388 in particular. (-:

[swankjesse]

As a workaround, you could keep a collection of the static imports you want, and build that collection while you’re building the code blocks.

[ronshapiro]

Another benefit of requesting static imports at the CodeBlock level is that when they are finally wrapped up into a JavaFile, you can verify that no other methods in that file conflict. If they do, then JavaPoet can ignore the request to static import, otherwise it can choose to qualify.

[sormuras]

If I never end up including it, then I don't end up emitting an unused import.

I'll modify #412 to skip unused imports.