How do I programmatically create a blockwise register with setreg()?

Explanation

Most register examples focus on interactive yanks, but setreg() lets you construct registers programmatically, including their type. Setting a register to blockwise mode is powerful when you need rectangular pastes that linewise or characterwise yanks cannot reproduce.

How it works

:call setreg('a', "foo\nbar", 'b')

• setreg() writes content into a register from Vimscript
• 'a' is the target register name
• "foo\nbar" creates two lines of stored text
• 'b' marks the register as blockwise (rectangular) instead of charwise/linewise

After this, pasting register a in blockwise contexts gives predictable column inserts, which is useful for templated edits, aligned prefixes, or synthetic test fixtures.

Example

Create the register:

:call setreg('a', "foo\nbar", 'b')

Then paste with "ap at a target column to insert a two-row rectangular block.

Tips

• Use 'c' for charwise and 'l' for linewise if blockwise is not needed
• Combine with getreg('a', 1, 1) when debugging exact stored lines
• This is ideal inside custom commands or mappings that generate structured text