Where is HAVE_SQLITE3_COLUMN_DATABASE_NAME defined?

[fractaledmind]

I am trying to understand how the gem determines whether or not to include the database_name method in the definition of the Statement class.

The code references a HAVE_SQLITE3_COLUMN_DATABASE_NAME constant in two places:

sqlite3-ruby/ext/sqlite3/statement.c

Line 414 in 5361528

#ifdef HAVE_SQLITE3_COLUMN_DATABASE_NAME

sqlite3-ruby/ext/sqlite3/statement.c

Line 452 in 5361528

#ifdef HAVE_SQLITE3_COLUMN_DATABASE_NAME

And the tests say that this method is defined or not depending on how SQLite was compiled:

sqlite3-ruby/test/test_statement.rb

Line 48 in 5361528

# This method may not exist depending on how sqlite3 was compiled

But, a search of the SQLite source doesn't return any use of this constant. And the docs say that the compilation flag used is SQLITE_ENABLE_COLUMN_METADATA.

So, how and where is the HAVE_SQLITE3_COLUMN_DATABASE_NAME constant set and how does that relate to the SQLITE_ENABLE_COLUMN_METADATA compilation flag?

[flavorjones]

Happy to answer questions! Let's do it in Discussions, though, and not Issues.

In the extconf (ext/sqlite3/extconf.rb), which is where the C extension is configured, you'll see this line:

        have_func('sqlite3_column_database_name')

The method have_func comes from Ruby's mkmf.rb or MakeMakefile module, and is documented here:

https://docs.ruby-lang.org/en/master/MakeMakefile.html#method-i-have_func

Relevant:

Returns whether or not the function func can be found in the common header files, or within any headers that you provide. If found, a macro is passed as a preprocessor constant to the compiler using the function name, in uppercase, prepended with HAVE_.

For example, if have_func('foo') returned true, then the HAVE_FOO preprocessor macro would be passed to the compiler.

Make sense?

[fractaledmind]

Makes perfect sense! And sorry for forgetting about Discussions again; still haven't formed the habit, but I'll get it switched on.

Seems this should be how I handle the progress_handler as well, as it can be present or not in the compiled SQLite source depending on flags.

Thanks for the clear answer!