Add a global exception whitelist (Issue 235)

lib/pry.rb

@@ -55,6 +55,9 @@ class Pry
     output.puts "from #{exception.backtrace.first}"
   end
 
+  # Don't catch these exceptions
+  DEFAULT_EXCEPTION_WHITELIST = [SystemExit, SignalException]
+
   # The default prompt; includes the target and nesting level
   DEFAULT_PROMPT = [
                     proc { |target_self, nest_level, _|
@@ -132,7 +135,7 @@ class Pry
         true
         # Don't catch signals (particularly not SIGTERM) as these are unlikely to be
         # intended for pry itself. We should also make sure that Kernel#exit works.
-      when SystemExit, SignalException
+      when *Pry.config.exception_whitelist
         false
         # All other exceptions will be caught.
       else

lib/pry/config.rb

@@ -29,6 +29,9 @@ class Pry
     #   Pry instances.
     attr_accessor :exception_handler
 
+    # @return [Array] The classes of exception that will not be caught by Pry.
+    attr_accessor :exception_whitelist
+
     # Get/Set the Hash that defines Pry hooks used by default by all Pry
     # instances.
     # @return [Hash] The hooks used by default by all Pry instances.

lib/pry/pry_class.rb

@@ -182,6 +182,7 @@ class Pry
     config.print = DEFAULT_PRINT
     config.exception_handler = DEFAULT_EXCEPTION_HANDLER
     config.exception_window_size = 5
+    config.exception_whitelist = DEFAULT_EXCEPTION_WHITELIST
     config.hooks = DEFAULT_HOOKS
     config.input_stack = []
     config.color = true