patch 8.2.2529: Vim9: Not possible to use legacy and Vim9 script in one file
Problem: Vim9: Not possible to use legacy and Vim9 script in one file.
Solution: Vim9: allow for "if false" before :vim9script. (closes #7851)
diff --git a/runtime/doc/vim9.txt b/runtime/doc/vim9.txt
index beec86f..def68d3 100644
--- a/runtime/doc/vim9.txt
+++ b/runtime/doc/vim9.txt
@@ -1051,9 +1051,9 @@
Namespace ~
*vim9-namespace*
To recognize a file that can be imported the `vim9script` statement must
-appear as the first statement in the file. It tells Vim to interpret the
-script in its own namespace, instead of the global namespace. If a file
-starts with: >
+appear as the first statement in the file (see |vim9-mix| for an exception).
+It tells Vim to interpret the script in its own namespace, instead of the
+global namespace. If a file starts with: >
vim9script
var myvar = 'yes'
Then "myvar" will only exist in this file. While without `vim9script` it would
@@ -1073,6 +1073,27 @@
One of the effects is that |line-continuation| is always enabled.
The original value of 'cpoptions' is restored at the end of the script.
+ *vim9-mix*
+There is one way to use both legacy and Vim9 syntax in one script file: >
+ " comments may go here
+ if !has('vim9script')
+ " legacy script commands go here
+ finish
+ endif
+ vim9script
+ # Vim9 script commands go here
+This allows for writing a script that takes advantage of the Vim9 script
+syntax if possible, but will also work on an Vim version without it.
+
+This can only work in two ways:
+1. The "if" statement evaluates to false, the commands up to `endif` are
+ skipped and `vim9script` is then the first command actually executed.
+2. The "if" statement evaluates to true, the commands up to `endif` are
+ executed and `finish` bails out before reaching `vim9script`.
+
+TODO: The "vim9script" feature does not exist yet, it will only be added once
+the Vim9 script syntax has been fully implemented.
+
Export ~
*:export* *:exp*