doc: warn about reassigning _ in REPL

thefourtheye · thefourtheye · commit 6417f8be140d · 2015-11-10T21:57:51.000+05:30
When users assign a value to `_` in REPL, it is prone to unexpected results or messing up with REPL's internals. For example, #3704. This patch issues a warning about the same.
diff --git a/doc/api/repl.markdown b/doc/api/repl.markdown
@@ -219,6 +219,9 @@ The special variable `_` (underscore) contains the result of the last expression
     > _ += 1
     4
 
+*NOTE*: Explicitly assigning a value to `_` in the REPL can produce unexpected
+results.
+
 The REPL provides access to any variables in the global scope. You can expose
 a variable to the REPL explicitly by assigning it to the `context` object
 associated with each `REPLServer`.  For example:

Original file line number	Diff line number	Diff line change
@@ -219,6 +219,9 @@ The special variable `_` (underscore) contains the result of the last expression
`219`	`219`	`> _ += 1`
`220`	`220`	`4`
`221`	`221`
	`222`	+NOTE: Explicitly assigning a value to `_` in the REPL can produce unexpected
	`223`	`+results.`
	`224`	`+`
`222`	`225`	`The REPL provides access to any variables in the global scope. You can expose`
`223`	`226`	a variable to the REPL explicitly by assigning it to the `context` object
`224`	`227`	associated with each `REPLServer`. For example: