Spell out that we want lexers in separate files.

1 files changed, 5 insertions, 1 deletions

diff --git a/doc/docs/lexerdevelopment.rst b/doc/docs/lexerdevelopment.rst
index c673b48e..27e5300e 100644
--- a/doc/docs/lexerdevelopment.rst
+++ b/doc/docs/lexerdevelopment.rst
@@ -20,7 +20,6 @@ containing tuples in the form ``(index, token, value)``.  Normally you don't
 need to do this since there are base lexers that do most of the work and that
 you can subclass.
 
-
 RegexLexer
 ==========
 
@@ -148,6 +147,11 @@ cloned from GitHub.
 Select a matching module under ``pygments/lexers``, or create a new module for
 your lexer class.
 
+.. note::
+
+  We encourage you to put your lexer class into its own module, unless it's a
+  very small derivative of an already existing lexer.
+
 Next, make sure the lexer is known from outside of the module.  All modules in
 the ``pygments.lexers`` package specify ``__all__``. For example,
 ``esoteric.py`` sets::